I have a damp problem on the ground floor near a chimney breast despite a treatment 11 years ago - what is your advice?
This is likely to have occurred following possible rising damp in the past from the fireplace hearth or moisture penetration from the chimneybreast. Was the wall re-plastered following the previous work or is it still the original plaster? Migrating salts usually lead to disintegration/breakdown/damp staining of old and sometimes replacement plaster. Obviously this needs a specialist on site inspection to diagnose whether the problem is caused by penetrating damp, water leaks, condensation, rising damp or whatever.
There is evidence that my property was damp proofed sometime in the past because you can see injection holes. But I still have areas of dampness inside at the foot of the walls. Can you explain this ?
There could be a number of reasons for continuing dampness - failure of the injected dpc, continuing bridging of the dpc eg because a plinth render has not been removed or part of the wall inside being below ground level and requiring the application of a waterproofing slurry coating. However the most common fault is in the replastering either because a lightweight plaster has been used instead of a sand and cement render with salt retardant additive or secondly where the new plaster has not been stopped short of the floor and so is bridging the new dpc
Any quick/easy cure for rising damp caused by flock infill of cavity bridging the DPC?
Proprietary cavity wall insulation materials per se will not cause moisture to cross the cavity and so bridge a dpc. So if the insulation has been installed as a 'retro-fill', there should not be a problem on this count provided the cavity is clean and free of mortar droppings.
Occasionally isolated damp patches can be caused in new construction if excess bricklaying mortar falls on the ties retaining the insulation panels in the cavity.
If it really proves to be a case of rising damp, then a remedial damp proof course installation will solve the problem. So an inspection by a trained and qualified surveyor is recommended.
Why do I have to have the plaster removed when you install a new damp proof course ? It looks sound enough.
Because it is highly likely to contain, as a result of the rising damp, ground salts such as chlorides and nitrates. These are hygroscopic which means that they can absorb moisture from the atmosphere so in cases of high humidity there is continuing internal wall dampness.
Replacing the plaster removes this problem and using a special salt retardant additive in the replastering will prevent any residual salts in the brickwork from migrating into the plaster after the rising damp has been controlled.
My house has a minor damp problem affecting attachment of wallpaper etc. What are the risks of leaving it untreated in short-medium term?
In addition to damaging your decorations, damp inside the home is unpleasant and can, in more serious cases, represent a possible health risk. So you are best advised to get it dealt with before it gets any worse.
A specialist survey is needed to determine the exact cause - it could be condensation or a case of rising or penetrating damp.
My terraced house is over 100 yrs old. I have damp on the inner wall which adjoins my neighbour. This isn't an outside wall. Can this be treated....will my laminate floor need to come up and are there any sort of grants available for this type of work?
Yes, a party wall can be treated successfully. Depending on a site inspection for confirmation, it may not be necessary to lift the flooring providing it can be adequately protected.
You need to contact your Local Authority regarding grant availablility as this will vary from area to area.
We had a dpc put in 3 years ago. Shortly afterwards we started to get mould in the areas that were dp. We had a new kitchen floor put in with a dp membrane, but have water rising from the floor. What can we do?
Mould problems are more often than not caused by condensation but you are best advised to call back the dpc installer and seek his view.
The floor appears to be a separate issue - the water could be resulting from leaking plumbing or, if below ground, hydrostatic pressure. You really need to seek specialist advice.
Damp directly below a window cill that is less towards the ground. The brickwork is spalling with some of the pointing in a very poor state. The brickwork appears dry. Could it also be accumulated rubbish between the walls causing bridging?
If it is a cavity wall, bridging is a possible cause of dampness. But this does not sound like a problem of rising damp, more likely a defect in the window cill and its ability to shed rainwater effectively. Check the seals around the window and the underside of the cill to ensure there is an adequate weathering drip and get the pointing repaired.
I have salt patches showing 14 months after tanking and injecting livin room wall. Contractor has come back, knocked out the affected areas and re rendered. Is this acceptable?
It depends really on what was the cause of the salt patches but the repair should prove satisfactory providing (and this is important) the correct specification of replastering has been used. This needs to contian a salt retardant additive such as the Peter Cox DryWall formulation which is specifically designed to hold back any residual salts originally drawn into the wall with rising damp.
I have a 60s bungalow with a thermoplastic tiled floor, the building dept of the council says that this was the damp proof membrane in those days, it has now failed tiles have cracked and lifted and the concrete is very damp, what can I do.
It would be surprising if as recently as the 1960's no damp proof membrane has been installed but it would have been of a lighter grade than used today and maybe the oversite was not blinded with sand. Either way the damp proofing protection measures look to have failed causing the dampness you are reporting.
One option for repair would be to lift and remove the tiles and then apply a two part high density resin coating over the floor screed paying particular attention to the wall/floor junction and ensuring a positive link to the wall dpc to ensure continuity of protection throughout the area.
A specialist damp control company should be able to help you with this.
Recently when I had work done on my damp problem, after taking the plaster off the walls, no time was allowed for the bricks to dry out before putting the new plaster on, then inject the chemicals.Should bricks have dried out before adding new plaster.
The key to replastering after the installation of a remedial dpc is the specification of the plaster. By definition the wall will be damp and will need to dry out but of greater significance is the likely presence of contaminated salts - chlorides and nitrates - which will have been drawn up into the masonry with the rising damp.
These salts can absorb and release moisture so that the wall may stay damp and the plaster may be damaged by crystallisation as a result.
A standard lightweight plaster is not suitable for this situation - instead a sand and cement render with a salt retardant additive must be used to counteract the salt contamination in the masonry and stop it migrating to the surface.
I have a sandstone converted barn. Water penetrates through the wall. We have had a new roof and gutters. Is there something we can seal the sandstone with. without damaging it.
There are a number of proprietary silicone based water repellent formulations on the market which will do the job you require. They are colourless but you would be advised to do a test area first because, depending on the type of stonework, there may be some slight change in appearance.
As always there is a range of different formulation qualities and you need to check the credentials, particularly UV resistance, ability of treated masonry to breathe (critical) and the projected longevity of the treatment.
Above all, bear in mind that once treated, the walls will shed water fast and so it is vital that any failing mortar joints are repaired and window/door surrounds are properly sealed. Otherwise weak points will be exposed quickly, the masonry could be damaged and water penetration will almost certainly result !
I have a single brick wall on a lean-to type extension. This wall is very damp because next door's drive is higher than the floor level inside. What can be done to stop the damp and mould?
In this situation the problem is one of lateral water pressure and it is exacerbated by being only a single brick wall with no cavity.
A solution would be to apply a waterproof sand and cement render to the inside of the wall to hold the moisture back and take this up to a level 300mm above next door's drive level. But it would also be vital to make a deep seal joint at the wall/floor junction and link the render to the floor dpm (damp proof membrane) to ensure continuity of protection.
We currently are experiencing problems onmost of our walls inside our home what looks like stains which spread over time but dont feel wet to touch do we need a damp course
It's difficult to say without more information. Rising damp problems would only affect ground floor walls and then no higher up than 1 metre. Condensation though might be a possibility.
You really need to speak to a surveyor who will be able to help identify the problem, so why not call our nearest local office?
On some of our ground floor walls we have what look like oily marks these spread over time we had a local damproofer out some readings high some ok no salt marks do we need a damp course
Presumably the local damp proofer gave you his analysis and recommendations. If you require a second opinion, contact your local branch of Peter Cox.
I have a damp mould problem in one corner of my living room. How can this be fixed ?>
This sounds like a condensation problem. It may be forming there because the corner is the cold spot in the room and the air is also stagnating there which is allowing the surface mould to form.
The mould can be removed easily enough by washing the surface with a fungicidal solution but it will re-form unless you manage to raise the ambient temperature and increase the air circulation in the immediate area.
Where can I buy a quality fungicidal solution from to treat mould
You should be able to obtain this from a Builders Merchant or large DIY store
I have recently converted a garage into a living room and kitchen. There didn't appear to be any dampness until after plastering and painting and now there is damp on part of a wall. I think it may be coming from higher ground (steps) outside. Help.
Your suspicions are probably correct. If the abutting higher ground is the problem, then in the past it was probably less apparent because of its location and because any dampness was removed by natural ventilation. On the face of it the likelihood is that the change of use of the space and then plastering over the wall with a standard finish has acted adversely on both counts.
But from here we cannot comment further - you need to commission a specialist damp survey to get an accurate analysis and more importantly a solution.
I have damp under the floorboards by the outside wall could this be penetrating damp due to the recent wet weather and what can be done.
There is a limit to the advice that can be given from a distance without further information and an on the spot examination. It depends on factors such as the floor construction; the position, type and age of the damp proof course; the presence of any high ground level outside; the history of any flooding; other building defects that may be contributing to the dampness.
And the solution will become apparent when the source of moisture has been identified.
Sorry, but the simple answer is to commission a special survey !
What method of replastering is recommended when a chemical damp proof course is installed and the replastering is required and must comply with Part L1B of the Building Regulations covering thermal insulation of walls.
A remedial dpc with replastering is not usually notifiable and unlikely to come within the remit of Building Regulation approval unless it is in conjunction with a larger refurbishment scheme which itself has to comply. So there may be two separate issues here.
However to reach the levels of insulation required under the Building Regs, particularly if it is a solid wall construction, it would be necessary either to install an independent internal dry lining system or fix insulation to the walls externally.
The replastering alone will not be sufficient but the specification itself should nonetheless still follow the normal recommendation i.e. a dense sand & cement render with salt retardant additive, not the usual lightweight plaster.
I had a dpc course done in 2004, the plaster was replaced but mould has now started to come back through how do i make sure this is a fault in the dpc and not a fault with the re-plastering
The simple answer is that you need to contact the company who installed the damp proof course and ask them to undertake a re-inspection - presumably you hold a guarantee.
A qualified (CRSTor CRDS) surveyor should be able to diagnose the source of the problem and if the installation is shown to be deficient, then you should be able to make a claim under the guarantee terms.
As you state, it could be the fault of the replastering and in the experience of this company this is the most frequent cause of continuing wall dampness. If a visual examination is insufficient, samples of the plaster used can be taken for definitive analysis of its composition to determine whether or not it has the required salt retardant qualities.
I have recently had a dpc installed by your company. I gave the information on replastering to a recommend plasterer, but the plaster covers the holes were the dpc was inserted with a gap between the plaster and the wood floor. Is this correct ?
Ideally the new plaster should end in line with the dpc drill holes and extend no lower. This is particularly important with the top skim coat. The gap between the plaster and the floor is also the correct detail.
Had a dpc course installed 3 years ago. I employed a seperate contractor to do the re-plastering to the correct specifications which they did do. Mould and damp has started to come back through. Can I knock off the plaster and just re-plaster or do i have
You need the advice of a specialist damp surveyor to determine exactly where the fault lies before taking any further action, so you should first go back to the company who did the original installation.
Mushrooms have suddenly appeared on the outside of my wall ~ what does this mean?
First and foremost it indicates that there is a serious level of moisture in the wall.
It could be a plaster fungus or, more threateningly, the fruiting body or sporophore of a wood rotting fungus such as Dry Rot. So the first imperative is to get it examined by a specialist to determine the exact species. That will determine the level of potential damage and what action should follow.
Whatever the diagnosis, however, it will be important to identify what is the source of the moisture - eg a blocked gutter or downpipe - and get this rectified as soon as possible. Why ? Because moisture ingress into building materials is the principal cause of building decay. This is what keeps companies like Peter Cox in business !
I've recently had a damp proof course, as well as re-plastering with the salt-retardant plaster (by yourselves). I was advised that I can paint the walls with a paint that allows moisture to evaporate from the brick, can you advise on a brand?
Most manufacturers produce a paint designed for use on new plaster, so it's a case of consulting your nearest retailer or trade warehouse for advice. Dulux for instance recommend their Dulux Trade Supermatt.
Our neighbours have repaved to the level of our airbrick. This covers up the old dpc membrane. 7 yrs ago we had a dpc installed by Peter Cox which is about 150mm above the current paving. We are worried that this will be affected?
If the dpc installed by Peter Cox remains 150mm above the level of the paving, then it should not have been compromised per se as this dimension is that recommended by the Building Regulations for the position of damp proof courses.
If the new paving is not obstructing tha air bricks in the wall, then again this sounds OK as air flow to the sub floor area is being maintained.
But as always it is advisable to keep an eye on the wall in question for any sign of dampness just in case the new paving has triggered in some way other opportunites for damp ingress.
You have recommended that we have a DPC and replastering done. You say we must remove kitchen units and appliances first. But just moved everything out today and there are LOTS of PIPES behind - how will this affect the replastering work?
It will make the re-plastering more awkward to do obviously but pipework is an everyday obstacle in kitchens. It will not in itself put the replastering at risk - because once the wall has dried out following the dpc installation, the objective is not to hold back water but instead to stop residual salts from migrating to the surface.
I have a terraced house with a single solid wall construction in the outrigger. There is signficant penetrating damp in the exterior walls. Please could you recommend what action I should take?
It is not really feasible in a FAQ section to give other than generic comments and advice. There comes a point when the best advice we can give is that you call in a trained and qualified specialist surveyor who can inspect the particular circumstances involved and give a properly judged analysis - and this is the case here !
We have a timber framed bungalow and noticed that we have a black damp patch on the exterior kitchen wall, white mould on the floor and spider web type mould under the kitchen units do you know why?
As regards the damp patch on the kitchen wall, check outside for any obvious signs of moisture. If none can be found, it is unlikely to be penetrating dampness and more likely condensation.
All moulds require moisture so there must be excessive moisture in or on the floor. If the floor is timber, then the 'mould' could be mycelial growth of a wood rotting fungi and needs identification by a specialist surveyor.
The mould you describe as spider web growth - if it's dark brown to black, it could be a type of wet rot called 'cellar fungus', but if it's white, then Asterostroma
I have some marks which look like salt appearing on only one internal wall. Is this rising damp and if so, what is the solution?
It could be any number of things and can only really be identified by a specialist damp surveyor examining all the circumstances and going through a systematic process of elimination before declaring a cause.
Giving snap judgements about rising damp has given rise (quite rightly) to many disparaging remarks about the damp proofing industry and is not an approach we could condone.
The height of the apparent salting, whether it's an isolated case or not, the degree of air circulation, whether a remedial dpc has been installed in the past ... these are amongst a number of factors to be considered before any reliable conclusions can be drawn.
My skirting board has started to crack. It's on the inner wall but next to a outside wall - is this damp ?
It could be dampness that has allowed a wood rotting fungi to develop - if so, this can lead to distortion in the facing surface of the skirting board. A surveyor generally makes a point of examining this detail for signs of dampness and timber decay.
You really need to lever off the skirting board first - as gently as you can to avoid damage - and then see what's happening behind.
If the area is damp, could there be a simple explanation ? What's on the other side of the wall for instance ? A bit of basic detective work is needed.
It might just be a local problem but if it looks potentially more serious, call in a specialist firm for advice.
We're redecorating our front room. We removed wallpaper in 1 top corner on a wall between living room and kitchen and noticed damp walls. There also was some fungus growing on the kitchen side. We can't find a leak or source of moisture. Any ideas?
Is this an outside wall ? If so, it could be a case of penetrating damp so you need to look outside for any signs of masonry dampness, leaking downpipe or overflowing gutter - there would typically be staining on the wall.
Otherwise you need to examine the room above and lift floorboards to see what's going on - perhaps it could be a leak from a radiator or heating pipe.
Whatever the cause of moisture - and the fungus confirms its presence - you need to be sure that the floor joists in the room above are not starting to rot.
How to deal with damp in concrete floor
In principle all concrete floors should include a damp proof membrane across the whole floor area and this should be linked to the damp proof courses in the surrounding walls to provide continuity of protection against ground moisture.
It follows that any breaks in the membrane will lead to dampness of one degree or another within the floor area. Because the source of failure is often so difficult to pinpoint, you could be looking at having to renew the floor in its entirety.
One alternative that may be feasible is to apply an epoxy resin coating across the floor to seal it against damp. Two coats are usually required with say 6 hours between, so it can be done in a day. But you need to be able to get at the whole floor area up to the surrounding walls so if it's a kitchen, all the units will have to come out. Surface preparation prior to application will be crucial but even so it will be less disruptive than taking up and renewing the floor.
Not a DIY job though.
Can damp soak into concrete floors as well as up the walls? The walls at the base are very damp and the concrete floor was moist under the lino? there is clear visible 'shadow' where the concrete is damp?
Most building materials are porous so concrete can absorb damp just as readily as brickwork. The reason why the concrete floor is damp is probably because under the lino there is no ventilation and so the moisture has no chance to evaporate.
Quite why the walls are damp in the first place can't be answered without a specialist survey - and that is recommended.
We have a damp problem on the walls in our hallway and joining lounge,the walls are wet to touch at night and dry in the moring,wall paper has started to peel off.any ideas?
If these were outside walls, you would suspect condensation being the problem. On internal walls it is more likely to be salt contaminated plaster. Walls that have been affected by rising damp suffer also from the presence of ground salts - chlorides and nitrates. These are hygroscopic which mean that they have the ability to absorb moisture which is released in conditions of high humidity.
So what could be happening is that in the evening when the house is occupied, the higher level of atmospheric moisture is resulting in the wall exhibiting surface dampness. By morning the atmosphere will be drier.
The solution is likely to be replastering up to a level of 1 metre above floor level using a special salt retardant additive but it will also be important to check that the protection against rising damp is working correctly, otherwise the problem will continue.
A small area of wall ajoining next doors cottage appears to be suffering small blisters..if the paint blister is split a small amount of water comes out. The wall is painted with anti damp paint. Is the problem rising damp or a burst radiator pipe in floo
It certainly won't be rising damp which is just that, dampness rather than free water. Sounds as though water is getting in behind the paint layer which is serving to hold it back rather than allowing it to disperse.
It could well be a problem of pipework failure somewhere. Check both sides of the wall to find out how far the dampness extends and look for any obvious sources of water eg pipe overflows, faulty guttering etc.
If you still draw a blank, it's time to call in a local builder.
I have bad rain penetration in the end gable of my old farmhouse. We can't find where the rain is coming in. Can you help?
This is one of those situations where it's difficult to offer constructive advice without being able first to see the building, its construction and where the water ingress is showing itself.
If the masonry and pointing looks sound with no evident points of possible rainwater penetration and any window surrounds appear properly sealed, you have to suspect a failure somewhere at roof level. But bear in mind that dampness will travel so where it manifests itself could be some distance from the actual point of entry.
It's really a job for your local builder.
I have damp that has appeared on my alcove wall in the living room. I thnk this has happened as the outside airvent had been blocked. This has now been unblocked however the problem still seems to be slowly getting worse. Water stain goes to app 80cms.
Difficult to answer this one without more information. Is it an ouside wall ? Was there a chimney there at one time ? Certainly getting the air vent unblocked was a good move but it probably needs an on-site inspection to determine the nature of the dampness and what is the most likely cause.
We have a small area in our hallway which gives a red damp reading on a meter used by a surveyor when trying to sell our house. It does not look damp, shows no sign of damp and feels good and dry. When does this meter register it as a damp area?
Electrical moisture meters can detect damp before it is obviously visible and they have the advantage of being non-destructive. They measure the conductance of electicity from a battery between the two metal prongs. However they are calibrated to detect the moisture content of timber, not masonry, so their readings are purely qualitative. They tell you where there is moisture, but not how much or what is the cause.
They need to be used with care and ideally just to plot moisture profiles which will aid the specialist surveyor in his diagnosis. Anything metallic in the wall behind - eg aluminium foil on the back of plasterboard or in wallpaper - will give a false reading.
With the dampness described it rather depends on its position in the wall and how far it extends. If low down just above the skirting, it could be a case of the plaster being bridged locally which is allowing moisture in the wall to circumvent the dpc. Alternatively it might be a case of condensation.
My house has been injected by another firm - it has failed. I don't want it injecting again. Do you put plastic membrane in like new construction or just inject?
If the remedial damp proof course has failed, your first course of action should be to go back to the original contractor. Is there a guarantee you can call upon ?
It needs to be established that it really is a matter of dpc failure and not some other cause for continuing dampness - e.g. incorrect plaster which in our experience is the most common fault in situations like this.
If the dpc has definitely failed, injecting again is the most economical and practicable solution and at Peter Cox we are confident that the system we use will be effective.
Installing a traditional physical (as opposed to chemical) damp proof course may be feasible but it's a laborious task, somewhat destructive, very dusty work and above all time consuming - which would be reflected in the cost. Peter Cox does not offer this but there are one or two firms who do.
I have a damp patch on the wallpaper below a bay window in my front room. The space beneath seems to be hollow. Is this likely to be due to poorly sealed windows, to genuine rising damp or to something else? Thank you.
Bay windows frequently suffer damp problems, so your description will sound quite familiar to a specialsit damp surveyor.
If the dampness is˙an isolated patch just below the window cill, then the likelihood is that it's condensation. This is˙quite common in a projecting bay where cold spots can form readily.
However if the dampness starts at skirting board level, it needs examining for the possibility of rising damp.
The other possibility with window bays is penetrating damp as often the brickwork is single skin rather than cavity construction, so you need to check the pointing, the window cill drips and the general sealing between the timber and masonry.
my ground floor is suspended timber.When it rains the area below the floor fills with water. what do you suggest
You obviously need first to check that there is no direct route for rainwater to channel from the oustide into˙the sub floor area.
Assuming that's OK, then this sounds more like an elevated˙water table problem and, if so, the moisture will be putting the flooring timbers at risk of fungal decay (wet or dry rot) making˙remedial action a necessity.
Where water is present from time to time, it is vital that the void below the floor is well ventilated, back to front and from the sides, to encourage a strong air flow which will help to evacuate the moisture..
Much depends on the depth of the void space but it may be feasible to stop the water appearing by laying hardcore over the site, adding a vapour barrier on top and then 'blinding' it with sand.
I have a retaining wall which is part of the interior of my house. The wall separates my house and the people at the back's garden which is higher. There are signs of damp coming through. Is this simple to fix?
The issue here is one of lateral moisture penetration from the higher ground level behind the retaining wall. If this wall was built in the first place just as a garden retaining wall, then it would not have been necessary to make provision for any waterproofing measures. But as it now forms part of your˙house wall,˙waterproofing is necessary and all this will need to be done on your side of the wall as the other side will presumably be inaccessible.
There are two options - either render the wall with a cement based waterproofing syatem to hold the dampness back (it's going to be messy and disruptive like replastering) or install a cavity drainage membrane inner lining to the wall which will channel any moisture finding its way through the wall away and out of the building (not so messy but equally disruptive).
Simple to fix ? - on paper it should be, but there'll be some grief˙to household life while the work's in progress.˙
My house is over 100 years old and has concrete floors throughout but I have a bad problem with damp. I've heard that all the floors will need to be dug up. Is that the only solution ?
Certainly it will be necessary to determine where the moisture's coming from, the floor's construction and whether or not it has a damp proof membrane fitted.
It is not necessarily the case these days that the floor has to be dug up. As long as you can get back to sound concrete,˙modern resin coatings can be used to resolve the dampness problem, although you may have to sacrifice the existing floor screed and re-lay a new one on top of the resin layer.˙˙˙
My house had a chemical DPC 25 years ago. It has solid walls and built 200yrs ago. On some sections of the interior walls a damp meter reading shows red at skirting level and up to 1ft in some places and 1 metre in others. About 6 months ago we dug out the soil to about 6inches below DPC holes as this was bridged and also a few small areas below skirting were bridged so we hacked this plaster off. The walls are still reading red and I wondered how long the walls take to dry out and read green? or do they never dry out and read green unless I re do the plaster as you have said in other replies with the salt retardent/sand and cement mix? Also the fact it was bridged, has this broken down the chemical DPC? or will it start working again now that I have un bridged these areas,or will it need injected again? Note the rest of the room is still working and showing green on meter reading.
It is usually reckoned as a broad rule that you should allow one month for every inch / 25cm of wall thickness for a wall to dry out after the installation of a remedial damp proof course.
In this case the bridging has provided the means for dampness in the ground to bypass the˙chemical dpc.˙But it should˙not have broken it down and after your clearance work the dpc˙in this area should continue to work satisfactorily again as it would appear to be doing in the rest of the walls.
However what looks likely to have happened is that the renewed moisture source˙has rewetted the internal plaster and possibly reactivated the salt contamination within it. This will be causing the meter readings you mention. So it does require internal replastering with a sand and cement render plus salt retardant additive as it does not sound as if this was applied when the remedial dpc was installed originally.
I have a sandstone bay which is double glazed. The double glazing is coming to the point of needing replaced, however, I have a thin green coat at some points on the outside bay and one of the sandstone columns is starting to discolour. I understand this is a common problem but am terrified I have rising damp. We have block paves in the front garden but I have checked the area between the pave and the window and there seems adequate space to allow for water drainage. Could you advise me please?
There's no need to be terrified of rising damp ! Because there are well proven solutions and they won't cost you an arm and a leg (in contrast dry rot can be˙far more serious).
The discolouration you mention indicates that the masonry is damp enough to allow the formation of algae growth and from the limited description given, yes it could be caused by rising damp.˙But bays like this are particularly prone to water penetration, often from high˙level, so it really requires a specialist survey to˙determine exactly where the problem lies.
Certainly the gap between the block paving and the wall is a positive feature˙as so often the installation of new patios˙or driveways raises the external ground level˙above the 150mm˙clearance below a dpc˙required˙under the Building Regulations.˙˙
I recently bought an inter terrace house where the previous owners obviously painted over the damp patch on the lounge wall. I have had the flashings resealed and still the damp gets worse. I also have mushrooms growing in one spot. The specialists concluded it is my neighbours tiled on top of concrete roof that is leaking and the water is tracking down and finding its way on to my wall. The neighbour has refused to pay as they do not have any problems. The proposal is to cut a hole into my ceiling and spray at 45 degrees a chemical solution which will allegedly travel up through the brick wall about 1.5m reach the top (covered by flashing) and then turn right and head into the neighbours concrete roof. Is this realistic, it does not sound logical to me.
The chemical treatment proposal described sounds more like masonry irrigation where a fungicidal solution is injected into a wall to combat infection with dry rot and to prevent the possibility of a recurring fungal decay outbreak after affected timbers have been replaced / spray treated. (It does not appear to be a situation where a waterproofing solution would be used.)
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This will have been proposed presumably because of the presence of ?mushrooms? which are almost certainly fungal decay fruiting bodies. But it can only be part of the required treatment because clearly you have a problem with wood rot and treatment by a specialist contractor is required, especially if this is identified as dry rot.
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This still leaves the need to locate the source of water ingress and to get this repaired because without it, no timber treatment can be successful (or guaranteed). The timber treatment work will necessitate exposure back to the last sign of infection so this may help to reveal where the water is getting in. You may need to get a general building contractor involved to help with the repair.
We have bookcases,almost floor to ceiling along the wall of our L shaped lounge (bottom of L) and the wall above skirting for about 9inches is completely black with mould. There is a clearance of about one inch behind the bookcases and the damp course from the outside matches with the floor level in the lounge. What is the problem?
The presence of mould indicates that the wall is damp at that spot and˙the bookcases are clearly not allowing sufficient air circulation to allow this moisture to dry out. The dampness constitutes a cold spot which has attracted condensation which in turn has led to the formation of mould.
So the question is - what's causing the dampness ? It could be a local fault in the damp proof course depending on the material and how old it is (possible but less likely). Or, because˙you have˙mentioned the height of the dpc relative to the internal floor level, you need to check the˙dpc˙on the outside to make sure that it is not being bridged by the external ground level.
The fact that the extent of the dampness is limited to a relatively small area, rather than the entire wall length suggests a localised problem where˙moisture is finding its way around˙the dpc.
How do I stop salt stains on the outside brickwok of our home, it only seems to be on the front of property.
There is no magic cure here. The best approach is to use a soft brush from time to time to remove the surface salts, taking care not to be brush too hard otherwise you will be pushing the salts back into the pores of the masonry.
There are salt neutralising solutions available but their effectiveness is likely to be short term and they merely mitigate the symptoms rather than treat˙the underlying problem.
Where salts appear on masonry, it is because there is some form of moisture movement going on. This is why it is a problem that occurs quite frequently on new build brickwork where the construction process involves a considerable amount of water, all of which has to dry out. Brick clays vary in their composition but if they contain a high degree of salts, surface efflorescence will occur from time to time whenever there is moisture movement to activate it.
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Can Platon Plaster Base be put onto existing internal plaster to save me hacking off all internal plaster and re plastering with salt inhibitor/cement base.
The simple answer is yes, because the material in question is a cavity drainage membrane used for below ground level internal waterproofing. And of course you can use a standard lightweight plaster.
However bear in mind one drawback - you will be increasing the thickness of the wall, thus˙losing˙some internal floor space. You may also need to check that there will be no˙alignment problems with adjacent walls.˙
There is also a risk - because you will need to get the right number of secure fixing points for the membrane, so the success of the˙repair will depend on how sound the exisiting plaster is.
Should any time in the future this plaster start to part company with the membrane or any of the fixing points˙loosen, this will threaten the integrity of the dry lining and therefore˙the inner wall finish. You would not be able to repair any such failure without starting all over again.
I have a damp patch outside my house which has been consistently present for 6 months or so. There is no evidence inside the house at all.
The amount varies daily. It is located on the 3 bricks below the airbrick and spreads roughly along the damp course for no more than the 3 bricks below the airbrick. I have cleared away the earth to the foundation level to ensure that there is no water from the ground coming up. But still it comes and goes.
It does not venture too much above the dpc but it can do by 1 cm or so on a heavy day.
I am at a loss as to what this is, other than taking out bricks or ripping up floor boards.
It sounds like rising damp - i.e. dampness rising˙from the ground below the foundations up to the barrier formed by the dpc.˙The fact that it is only apparently occurring in a localised area could suggest alternatively there is˙a water leak somewhere inside the building (and this is worth checking out) or˙perhaps, salt contamination of these particular bricks.
Where it rises above the damp proof course, there may be a localised failure of the dpc itself. ˙The fact that comes and goes will be due to surface evaporation confirming the correctness of your action in clearing away the earth˙outside.
Other questions a surveyor would be asking himself include - Does the moisture intensify with rainfall ? ˙Is this a cavity or solid wall ? Is there any other possible source of moisture nearby -˙drainage system, rainwater goods, internal pipework etc.
My house is a 1930's built Accrington brick detached property. I have recently had a small extension built to the side. The actual plan specifications stated the fitting of a cavity tray between the new and existing buildings but apparently this was not done. The extension which has a solid concrete floor, whereas my original house is suspended floorboards.
There was an initial problem with rising damp that my builders thought was due to a defect in the DPC of the original house in one particular area which they fixed by removing those bricks and relaying.
My concern is I have just removed the laminate flooring in my front room to which the extension was built and now opens into and find that the floorboards especially around the chimney breast are really damp with obvious signs of water staining. Basically the wood seems sound with little sign of any soft rotting but there is a musty smell and certainly mould growths were apparent under the old decor.
This sounds like a case of reduced sub floor ventilation below the existing room and it would be advisable initially to check that the existing air bricks have not been blocked off by the new solid floor in the extension.
This is a common problem with extensions and where it is going to happen, it is normal practice to run a duct (say a 150mm drain pipe) from the original vents˙under the new floor to the new external wall in order to maintain air flow. However even so˙the level of ventilation capacity will be˙significantly reduced.
So the answer could be to try to increase air flow˙below the original suspended floor via the remaining external walls. This may not be easy but other than conventional measures, one option could be a to install a mechanical ventilation unit˙in the sub floor area to ensure positive air flow.
As always, an inspection by a qualified specialist damp surveyor is the recommended option.
One exterior wall of my house has about two feet of bricks below the dpc. In this area there is a lot of efflorescence and a number of bricks are crumbling on their exposed face. Is this likely to be caused by rising damp?
Yes, this is clear evidence of the way moisture in the ground rises up through porous masonry. It's a common sight if you look closely at the foot of building walls. That's why the installation of a dpc is a standard building specification.
The efflorescence you see is the result of chlorides and nitrates˙being brought up in liquid form in the ground moisture and then reforming as salts as moisture evaporates through the face of the bricks.
The crumbling of the brick face is a consequence of this salt formation probably exacerbated by the action of frost which will cause the moisture in the wall to expand as it freezes and so˙add further pressure˙within the structure of the bricks, resulting in some surface fracturing.
I have an outhouse I am trying to make into a dining room. The floor isn't damp proofed. If we raise the floor, do we still have to damp proof underneath?
Because the new dining room when created will constitute a habitable space as defined under the Building Regulations, it will need to comply with˙standard building˙specification requirements˙as far as damp control is concerned.
So if it's a solid flood construction, you will need to lay a damp proof membrane across the oversite concrete tied in to the˙wall dpc's to create a continuous barrier against damp ingress. It will also be necessary to link this in with the main house dpc.
Alternatively if you are building a timber suspended floor, damp proof membranes will need to be situated on all masonry that forms a˙bearing point for the floor joists.˙The solum is best blinded with a membrane covered with sand or aggregate.
In any event you should consult your Local Authority Building Control Dept first˙- one of their Building Inspectors will˙be able to advise you further.
Please can you help me make my final decision on whether to move to this lovely 16th century house. I recently viewed it and there were a few water puddles on the lino flooring and on the rug. Also there was an old wooden coat stand where the base was full of water. Now whether the water was coming from a leak above or under the lino, I'm not sure - the landlord wouldn't tell me. Also the one wall has a lot of ring patches on it which I assume is damp patches. Do you think this could be serious for my health or not? It has a very musky smell there too....
If there is dampness in a property, then in principle this could have detrimental health effects but to what degree depends on the susceptibility of the individual resident. Usually those most affected are the young,˙the elderly and anyone with an asthmatic condition or other breathing difficulties.
Properties as old as this are more than likely to have problems with damp but when it was built, there were no worries about modern refinements such as central heating, draught proofing˙and insulation. On the contrary draughts via doors and windows plus open chimneys were the way these buildings kept damp at bay. Even then some level of dampness was tolerated, in a way that is not so acceptable today.
Owners of historic property have to take issues like this in their stride and be prepared to˙carry the much higher costs of repair and maintenance. Solutions can certainly be found when problems arise (as they inevitably will) but unfortunately that's the price of living in a˙listed home.
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I had cavity wall insulation done in 2002 and three year ago damp patches came through on the gable end in the sitting room and two bedrooms.I contacted the company that did it and a check said that the filler was dry but there could be some place in the cavity that were not filled so it was re-done and after a three momth wait I painted the wall but damp stains have came through and the plaster is still cold to the touch. What can I do replaster or try a stain stopper?
If you use the yardstick often applied in the damp proofing industry of one month per inch (25mm) of wall thickness for a wall to dry out, you were possibly premature in repainting as probably the wall is˙still wet. The fact that the plaster is still cold confirms that this could be the case. ˙
So you need to give the wall a bit longer but if the problem persists, replastering or applying a stain stopping treatment will be merely masking the problem, not solving it. If the first sign of dampness was 4 years after the cavity wall insulation was installed, maybe this is not the culprit. Even if the coverage wasn't 100%, that should not be reason for dampness suddenly to occur.
Perhaps you need to check for other possible causes on the wall in question including the roofing and rainwater disposal system.
My house was built in 1872. The outer wall at the rear of the property seems to be holding moisture in certain places which is causing wet looking patches on the inside. Could you advise the best way to treat this problem. Trying to decorate but the paint is flaking in those patches
Decoration is fruitless because it is merely attempting (and failing) to disguise the problem and paint will always flake away when the substrate or wall surface is damp.
You have to bite the bullet and find out what is causing the wall dampness in the first place and then get this rectified before spending any more money on internal decoration.
The first place to look is outside - what's the condition of the masonry at the point where it's showing damp on the inside ? What's the pointing look like ? Are the gutters and downpipes sound ? Is there any high ground level which is bridging the damp proof course? If it's rendered, are there any cracks ? Could there be failure at roof level? And so forth.
If you can't find an obvious reason, then it's probably time to call in a damp control specialist.
I have a mid terreced house that is suffering from damp on a number of the outside walls. I know that I have to hack the whole lot off and re-render including new guttering and facias etc (the guttering is okay I might add, but ugly), but I cannot afford it until next year, and I am looking for some short term solution to get me through the winter. I have tried a silicone seal coating in the worst places, but it doesnt seem to have improved that much. Is there a product on the market that I could use to get me through?
The silicone sealing may in fact be working quite satisfactorily and stopping any more moisture getting into the wall but˙the˙masonry behind the render will still˙be wet and will need time to dry out - it will take something like one month per inch (25mm) of wall thickness as a rough guide. So maybe that's the reason for the continuing internal wall dampness.
And that will be the problem with any short term exteranl solution that you hope will tide˙you over the winter.˙
However it does˙also depend on whether the problem actually is failure in the external render. Could it be for instance condensation ?˙
As a temporary interior expedient you could consider using a dehumidifier to try to accelerate the wall drying out process and this would address the condensation possibilty at the same time
I have a terraced property in Carnforth Lancashire approx 130 years old. I have lived in it for around 3 years and had some remedial damp proof work carried out I hope with success. The only timber floor left in the house is in the lounge where I have recently noticed a damp odour and after investigation found that the floor joists have become very wet. If as I suspect the ventilation has been compromised by the addition of the concrete floors enclosing the lounge, would the best option be to remove the existing wood floor and replace it with a concrete floor, using say 100mm jablite and a visquine damp proof layer.
Your diagnosis is probably correct as this is an all too common scenario, all because of omitting the simple step of running a vent pipe through the new concrete floor to maintain air flow to the existing timber sub floor. Without any action on your part, there is a strong risk of fungal decay breaking out in the floor joists.
As to the best option it depends on whether it is feasible to add further air vents under the floor to ensure better airflow. Where this may be difficult, for instance if there are insufficient external walls), you could consider using a powered ventilation unit of the type normally used to combat condensation (our local office can provide more details). Certainly if the floor is retained, the timbers will need fungicidal treatment.
If you have no particular attachment to a timber floor and are prepared for the disruption, then a concrete floor˙(sadly, for a timber treatment company!)˙will have its attractions, but you'll need to check out the comparative costs.˙˙
We live in a terraced house which was built around 1920's. I don't particularly know of any dpc history but the house was rendered on outside about 2 years ago. We have wet patches on our wall but starting midway up the wall above the rail; this is an outside wall. We have checked airbricks, rendering and gutters but there is nothing obvious to suggest why water is coming in. Everything I have read about damp etc goes on to say it rises from the bottom, which ours doesn't. We suffered last winter with condensation but as it's our first house we didn't realise what damage we were doing so since then we have vented the house, open windows everyday, don't put washing on rads, have the extraction fan on while cooking dinner (open plan living/kitchen area) but now this has started happening, I don't see how it could be condensation again..........any ideas what this could be??
What may well be happening is that hygroscopic salts in the masonry˙have˙absorbed˙atmospheric moisture and, now that temperatures are beginning to fall with the onset of autumn, this moisture is condensing and causing the wall surface to appear wet.
The presence of salts is frequently an issue with problems of rising damp and even if a remedial dpc is installed, if the wall isn't replastered with a salt retardant additive, then any residual salts in the masonry can cause just this kind of problem.
Two other facts you mention could be significant. Firstly˙the house having been˙rendered recently which suggests there may have been prior problems with the wall and˙it could˙still be drying out, even if a dpc had been installed. Secondly the height of the wet patches on the wall which could indicate that any replastering has not been taken up high enough to neutralise all the˙salt activity.
You're certainly doing the right thing with your general measures to mitigate condensation problems but this additional issue probably calls for a survey by a specialist to really get to the bottom of it and find a lasting solution.
How do I stop a damp patch inside a ground floor bay window? In the past there's been a leaking roof but this has been all sorted and new joists and dpc fitted. However outside ground level is above inside floor level so the outside vent is also above inside floor level! Foot square of mould etc inside.
If you yourself commissioned the new dpc and floor joists, then your first course of action should be to go back to the original installer.
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It rather depends on the position of the dpc in relation to both the internal floor level and external ground level. Ideally the dpc needs to be a minimum of 150mm above ground level. However if there is a step in levels and the dpc is above the internal floor level, it follows that there will be a section of wall exposed to ground dampness. The recommended way to overcome this is to apply a waterproofing slurry coat to prevent damp ingress at this point. Alternatively can anything be done to lower the external ground level ?
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It may be only mould growth now but unless the new joists ends have been protected as they should have been, you could be looking at the more serious issue of timber decay if the dampness persists. You should also check that there are other correctly positioned vents to get air circulating around the sub floor.
Our house was built in 1971 and a conservatory added 10 years later. We have now noticed above the conservatory there is a huge patch of brickwork which never dries out. I don't know how long because an observant neighbour informed us. What can it be? There is no sign of anything inside the house.
It's unlikely to be anything to do with the conservatory as this is˙nearly 30 years old.˙It sounds more like a failure in the main house guttering or perhaps a leaking downpipe. Even so it's surprising that it never dries out but possibly it's a north or east facing elevation or otherwise sheltered from drying sun and wind.˙
The best advice is to carry out˙some rudimentary observation and detective work˙over the next few months˙- this should start to˙reveal the answer to the conundrum.˙
The fact that nothing is visible on the inside proves the value of modern cavity wall construction.˙˙
I moved into a rented property about 6 weeks ago and i am experiencing a lot of damp and mould. It is growing on the walls, it is growing from the top of the wall to the bottom,under the flooring etc.
I have had builders out to the property and they have advised it is damp coming through the brick work and rising damp. Is this correct?
Also I have low level damp in the built-in wardrobes - what does this mean?
Quite clearly the property has serious dampness problems but there could be a host of reasons of which rising damp might be only one, and even then it's unlikely to be˙the main problem.
Penetrating dampness seem the most probable so it is surprising the 'builders' have not been more helpful, as the roofing, guttering, brickwork pointing etc all need close examination.
It is difficult to offer constructive comment from a distance apart from to recommend that˙you call on the advice of˙a specialist damp surveyor.
The dampness in the wardrobes though could well be a condensation problem but if they're on an external wall which itself is damp for other reasons, you'll have to resolve that source of dampness first before condensation on the inner surfaces can be eliminated.
My house is over 100 years and sweats.This causes mould and rotting floors and walls. How do I stop this?
Houses built 100 years ago (in the Edwardian period) were all solidly constructed˙with coal fires for˙heating, open flue chimneys, sash windows˙and lots of draughts and natural ventilation. We've modernised them, blocked up the chimneys, installed central heating, double glazing and draught proofing, as well as adding showers and modern kitchens. Outside we've added modern patios which often block up the original ground floor air vents.
The result more often than not is condensation and if this affects the sub-floor area, wet rot in joists and˙floorboards. Worse still dry rot could result.
So you need to address the issue of ventilation and increasing air circulation in your property. Mould is a tell tale and a warning to take action before things get worse.
I live in a sandstone cottage built in 1710. The outside 3 walls in my bedroom are streaming with damp. How can I stop this ? There is no guttering on these walls ! Is there anything I can paint on the walls inside or out to prevent this?
The absence of guttering is clearly a serious factor and this needs rectifying. At this age the property is presumably listed so you will˙need to consult the conservation officer at your local authority offices. The same goes for any exterior coating - quite whether it is advisable depends on the wall construction and the type of coating proposed because many formulations do not have sufficient water vapour permeability.
If there is dampness on the inside of the walls, this could theoretically be caused by penetrating damp from outside, but it is more likely to be condensation. Again a wall coating will be purely cosmetic and won't address the basic issues of heating, insulation and ventilation which lie behind the problem of condensation. More information on a possible solution is given on the condensation page of our web site and you can download a leaflet for homeowners as well.
On two outside walls we had a tide mark of damp above the skirtings. We removed the skirtings and found a rotten joist, woodworm etc. We have dealt with the wood problems and injected a DPC, replastered using render type plaster and the wall seemed dry. When we place the skirtings up to the wall, they get wet behind them with an increasing level of height over time. One of the internal walls is some 2 feet above ground level and the wet is at this height and higher internally. It seems like condensation but it is strange. Any help appreciated.
There are a number of possibilities. Firstly insufficient sub floor ventilation causing moisture to be absorbed into the plaster and tracking up behind the skirting. Secondly the plaster may be˙bridging the dpc and putting back the skirting is both hindering drying out and causing a build up of moisture. Thirdly˙the walls have yet to dry out or, if they should have done so by now, the dpc is not fully effective (in which case refer it to the specialist dpc contractor you used).˙
How can I tell if the house has condensation problems or it is rising damp ?
Rising damp is a specific ground floor condition manifesting itself˙on outside walls (although it can also affect some interior walls)˙starting at the skirting boards and˙rising up to no more than˙1 metre˙above the floor level. It also has a tendency to peak at the corners of the wall.
Condensation on the other hand can arise anywhere in the property where the right atmospheric conditions prevail dependent on˙temperature, humidity and insulation.
The tricky problem however is deciding between rising damp and condensation as the cause of ground floor wall dampness˙and, sadly, rising damp is incorrectly diagnosed all too often. This is where the skills of a trained and qualified (CSRT) surveyor are˙needed because the two conditions have very different moisture profiles.
I have a brick built miners cottage which is approx 100 years old and is rendered on the front elevation. There is a 100mm spacing between the bottom edge of the rendering and the pavement outside.
The inside walls have what appears to be a 1 metre high cement mixture rather than plaster and at the base about 500mm apart are small round vents about 30mm in diametre which have tubes behind them going into the wall. I have a Royal Doulton Damp Proof Certificate from approx 35 years ago and assume that the vents are to do with this. However I am about to refurbish the rooms and wondered if there was a way to remove them for something more modern as they prevent wallpapering or if after all this time I needed to conduct any type of maintenance on them to maintain damp proofing. There does appear to be salt marks (white powder) on the walls, which I have scraped off, they walls are quite uneven so I would like to plaster and repaint but would not want this staining to come back through
The dpc system˙was˙probably installed by Doulton Wallguard and it consists of ceramic tubes which are designed to attract wall moisture˙and provide a means of evacuating it via natural ventilation. It was marketed as an alternative to chemical dpc's and although Wallguard no longer trade,˙similar systems are still available today when they have particularly appeal to the 'green' lobby.
The internal wall finish sounds like a salt retardant cement based render of the type˙recommended by Peter Cox to hold at bay ground salts drawn up into the masonry prior to the dpc installation. The fact that some salt activity is visible after 35 years suggests two things - a) the dpc is not wholly effective in preventing rising damp and b) there is continuing salt activity so it would be unwise to remove the render.
The risk with ceramic tubes is always that they are prone to blockage by excessive salts and this in itself reduces the surface area for moisture˙evaporation on which the system relies.
We would recommend a survey by a qualified damp control specialist to assess the situation and to consider the available options which might include the installation of a new dpc.
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I had large patches of damp appear after having some standard plastering done. I then had a damp survey done by a specialist surveyor and was told the DPC was bridged due to the plastered walls on 3 sides of room meeting directly with the flooring. I was advised to remove the plaster up to approx 2 ft, re-plaster with porous plaster, leave a gap between the new plaster and the flooring and fill with anti damp solution (some kind of spray was used). 3 months later I now have a tide mark under the back window sill (external wall) approx 1 & half feet up from the skirting boards. There are also slight markings around the other walls. Can you explain what has happened?
Your first point of call ought to be˙the specialist surveyor because his advice has clearly not resulted in a resolution of the damp problem.˙
The initial diagnosis of the source of dampness sounds valid˙but the˙specification of the replastering looks to be faulty.˙The wall dampness will have been accompanied by ground salts and because these are still in the wall, you need a salt retardant sand and cement render˙to hold them at bay. What appears to be happening is that salts are migrating to the surface and as the moisture evaporates, a tide mark of salts is left.
˙The specification Peter Cox recommends is illustrated on the replastering page of our web site. It's maybe no consolation but using the wrong plaster in this situation is a very common fault.
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