What is Lateral Damp

Lateral damp (also known as penetrating damp) is when moisture is allowed to enter the structure in a horizontal direction. Gravity then causes the downward movement of the damp into other areas. Penetrating damp can create isolated patches of dampness that increase in size after periods of heavy rain. The damp can occur at any level, unlike Rising Damp which usually rises from the ground up to 1.2 metres high. Lateral or penetrating damp is usually from a source too difficult to control and only an expert with a moisture metre detector can evaluate the difference in rising and lateral damp. Sometimes the problem may also require a plumber to pressure test the pipes to eliminate a leaking pipe being the main problem.

Lateral damp is also known as penetrating damp

Causes of Lateral/Penetrating damp

▪ leaking water supplies or waste pipes
▪ fretted mortar joints
▪ defective brickwork
▪ failure of tile grouts in showers and other wet areas
▪ poorly functioning membrane in wet areas
▪ cracked render
▪ poor flashings
▪ defects in adjacent property outside the owners control
▪ air-conditioning or hot water system overflows can also lead to small localised patches of dampness.



What is Falling Damp

Falling damp is like lateral damp and starts in the roof and gutters caused by poor flashings, damaged roofing, blocked and/or damaged drains and leaking gutters. Fallen leaves, bird droppings, moss and dirt all contain acids and salts which when carried by water into the masonry can cause decay.