Penetrating damp

Penetrating damp is one of the most common causes of dampness in a property. It is the result of water infiltration into a property often resulting from an external defect. It is sometimes referred to by other names such as water ingress or lateral damp.

Despite what many people think, your property is not built from waterproof materials. Most bricks are porous which means they can absorb moisture through things such as wind driven rain. This is exacerbated by flaws such as cracks and damage to the brickwork.

Keep reading our expert guide below to find out the following:

• What causes penetrating damp?
• Can cavity wall insulation cause penetrating damp?
• How to identify the signs of penetrating damp
• Problems caused by penetrating damp
• What is the difference between Penetrating Damp and Rising damp?
• Can I get penetrating damp from next door?
• Does penetrating damp cause mould?

If you want immediate attention for your damp problem you can click the button below to book a survey with our expert surveyors today.

Signs of penetrating damp can appear on the internal and external walls of your property.

Any damp patches that appear on internal walls, windows and ceilings may indicate there is a penetrating damp problem and these damp patches will often appear worse after prolonged periods of rainfall. If any damage or vegetation growth on the external wall correspond with the location of the damp patches on the internal wall this is another sure sign that penetrating damp is the root of your problem.

Common signs of penetrating damp include:

• Damp staining on external walls
• Damp patches on walls or ceilings
• Wet and crumbly plaster
• Isolated signs of spores or black mould
• Moss and algae growth on the outer walls of the building
• Cracked and damaged brickwork
• Damp staining caused by leaky or overflowing gutters or downpipes

Penetrating damp often occurs due to moisture entering the property through some sort of defect in the fabric of the structure.

Penetrating damp can also occur if brickwork is too absorbent. As bricks age they can become worn and more absorbent as a result. When this is the case water repellent coatings can be used.

In summary, any combination of the following faults can cause penetrating damp:

• Leaking gutters and downpipes
• Blocked gutters
• Ageing porous brickwork or stone work
• Defective pointing or flashing
• Missing or damaged roof tiles
• Spalled bricks and degraded mortar
• Inadequate drip grooves under window sills
• Defective seals around doors and windows
• Burst pipes and other defective plumbing

Because penetrating damp is caused by faults in the property allowing water to pass through the wall, the signs of penetrating damp are often more prominent when it rains.

When blown to the correct density, cavity wall insulation on its own will not cause penetrating damp. However, if the wall is porous and the pointing defective, moisture will come to bear on the insulation.  At this point, if the insulation is blown too loose, moisture can track across to the inner leaf and appear on the inside wall.

Another potential failure can occur when voids are left in the blown material. This allows cold air to form and the defect becomes a cold bridge. This can cause dust to stick to the wall surface or condensation to form, followed by mould in the pattern of the defect.

Once the cavity wall insulation becomes wet, it is not possible to dry it out. Damp walls act as cold bridges and cool the inner wall surface, which then increases the amount of heat required in the property, increasing heating costs.

Any conditions that cause masonry to become damp, should be avoided.

If penetrating damp is left untreated it can cause significant structural damage to your property. This can include deterioration of plaster in walls and ceilings and can even lead to wet rot and dry rot in structural timber in trusses, joists and beams.

Beyond these serious problems penetrating damp can also cause aesthetic damage to wallpaper and paint and lead to an unpleasant musty smell in your home.

Penetrating damp can often be confused with rising damp as both can cause damp marks on the walls of a property.

The main differences are that signs penetrating damp can show up anywhere on your walls or ceilings, but rising damp will show on the ground level typically no higher than 1 metre from the floor.

To find out more about the difference between penetrating damp and rising damp check out our video below