Lateral damp is when groundwater penetrates sideways into a property through cracks or porous building materials.
It can affect any floor which is in contact with soil, but is most common in basements.
Areas that have high water level – such as Fulham, Putney and Richmond – are more vulnerable to lateral damp.
You can learn more on the causes of lateral damp in our article.
How to spot lateral damp
Look out for paint that’s peeling or has a bubbly appearance, or plaster that’s discoloured and/or crumbling.
Walls affected by lateral damp are also likely to be cold and wet to the touch, and if hygroscopic salts are present, then you may see a white, chalky coating as well.
Black, sooty mould is a dead giveaway of a damp problem and can be just as easily smelled as spotted.
Lateral damp causes mould and property damage
If untreated, lateral damp can ruin paint and plaster, spread mould and cause electrical failures and shocks – none of which you want in a basement you intend to spend time in.
Lateral damp causes more problems than just an unpleasant basement, it can also lead to severe structural issues for walls which the entire building is relying on for support.
To prevent damage from lateral damp, building regulations require that all new builds with basements and all basement extensions are equipped with tanking systems.
You can learn more about treating lateral damp in our article.