At the mercy of the elements
Lorbottle Hall in Whittingham, Northumberland is a grade II listed building dating back to 1789. Like many Georgian properties it has a remarkable symmetry and high ceilings throughout and offers some beautifully proportioned Georgian reception rooms. Externally, it has been constructed with Northumbrian stone under a slate roof with impressive and large sash windows.
Facing a double threat
Our team were asked to investigate rising damp and woodworm.
Chris Hansom, Senior Surveyor in our North East regional office said: “This lovely country home had problems with rising damp and rainwater ingress due to some gutters and downpipes being in poor condition, with green algae growths to the external masonry resulting from them leaking. This meant that mortar joint pointing was also in poor condition.
“The apparent erosion by weathering of the stone facings to some walls had resulted in this masonry becoming porous and prone to rainwater penetration and it was important these issues were addressed to stop the problem getting worse.”
An inside inspection of the ground floor indicated the presence of rising dampness to several walls which we believed was due to the lack of an effective damp proof course.
Chris said: “Rising dampness is a common, naturally occurring phenomenon caused by moisture rising via capillary action into the building fabric. Most masonry building materials can be subject to rising dampness and, without suitable protection, a property can suffer. Effects can include unsightly mineral salts, moisture staining to decorative surfaces and, in severe cases, the breakdown of wall plaster due to salt contamination.”
Chris advised on the installation of a chemical damp proof course incorporating the Peter Cox DryWall Diffusion Process to the affected areas. The great thing about our system is that it can be installed in solid walls from one side and so causes minimum disturbance.
The material used is non-flammable and non-toxic and so poses no fire risk and means the property can remain occupied with a minimum of inconvenience to the occupants.
We drilled and inserted the DPC at a level up to 75mm above the floor and also advised the client on the importance of using the right plaster afterwards.
“After installing a DPC it is really important that the new internal plaster is capable of preventing hygroscopic salts affecting the wall surface,” said Chris. “This means using our ‘Dry Wall’ coating system or using the metal lath lining system. Under no circumstance must the Dot & Dab method be used.”
A further problem at Lorbottle Hall was woodworm infestation caused by the Common Furniture Beetle (Anobium punctatum). This wood-boring insect is responsible for about 75% of all woodworm damage in this country and will attack softwood and hardwood.
On inspection of the roof void to the main house and the roof over the House Keepers apartment, we noted moderate to severe infestations to rafters and trusses in some areas.
This was treated by preparing all exposed roof timber surfaces and applying insecticidal fluid to all exposed surfaces.
Stopping the rot
And finally, attacks of fungal decay by Dry Rot (Serpula lacrymans) were treated by cutting out all structurally weakened timbers, applying a surface application of fungicidal fluid to the stonework and wire brushing the surfaces. Holes were formed at 450mm staggered centres in walls in excess of 150mm thickness and fungicidal fluid applied to each hole together with a surface application to masonry.
“Fortunately the dry rot, damp and woodworm problems on the property were able to be treated and repaired,” said Chris. “Those areas we treated on the Hall are now guaranteed for many years to come.”
