What Does Rising Dampness Mean In Construction?
What Does Rising Dampness Mean In Construction?
Rising dampness in construction is a relatively rare form of dampness that affects the walls of buildings. It occurs when moisture from the ground travels up through the walls by capillary action.
This can cause damage to building materials such as render, efflorescence, and cracks in masonry. To prevent rising dampness, modern homes are built with a DPC (Damp-Proof Course).
Rising dampness is often caused by poorly managed rainwater or groundwater intrusion, plumbing leaks, or inadequate ventilation. Building-code requirements for vapor retarders on the interior side of exterior walls and ceilings may also have an impact on building dampness.
Studies have found that the prevalence of visible dampness in houses and apartments ranges from 10-50%, depending on climate and other factors.
What Causes Rising Damp?
Rising damp is caused by capillary action absorbing moisture from the ground and traveling up through walls.
This can saturate walls with pollutants, such as saltpeter, and cause structural damage to timber structures. The main cause of rising damp is a damaged Damp Proof Course (DPC), which are thin, lengthy tubes (pores) in masonry that allow moisture to ascend.
How To Prevent Rising Damp?
The most effective way to prevent rising damp in buildings is to install a damp-proof course, such as a waterproof plastic membrane along the mortar line of the building.
Other methods include using water-repellant metallic soaps, such as calcium and aluminum oleates and stearates, treating dampness with Dryrod Damp-Proofing Rods, and using cavity walls or hallow walls.
How To Identify Rising Damp?
The key signs of rising dampness include tide-mark damp stains on internal walls, salts visible in the plaster of internal walls, damp and decaying skirting boards.
Evidence of a tide-mark effect where dampness stains appear above the skirting boards on the ground floor walls up, and efflorescence on interior walls, visible damp patches on walls, and black, green and white mould.
What Are The Signs Of Rising Damp
The signs of rising damp include flaky or bubbling plaster, tide-mark damp stains on internal walls, salts visible in the plaster of internal walls, efflorescence on interior walls, visible damp patches on walls,
Black, green, and white mould, damp and decaying skirting board, and damaged timber on the wall.
What Are The Effects Of Rising Damp
The effects of rising damp include respiratory problems, allergies, asthma, pain and even lung diseases.
This is due to the presence of mold spores, wallpaper peeling and paint blistering, brick becoming heavily loaded with moisture, mould and mildew growth, and crumbling of outward masonry.
What Is The Difference Between Damp And Rising Damp?
The primary difference between rising damp and condensation is the source of the moisture. Rising damp is caused by water from the ground, such as rainfall leaks, inadequate drainage, or faulty plumbing, ascending through the walls and floor without being stopped by a damp proof course.
Condensation is caused by humidity in the house from activities such as cooking, bathing, and breathing.
Rising damp can be identified by tide marks on walls that will not appear higher than one metre from the ground, as well as salt deposits on the wall, rusty nails within skirting boards and/or decaying skirting boards, and aesthetic damage to plaster, paint, and wallpaper.
Condensation can be identified by black mould which can occur on any walls of the property.
To treat rising damp or condensation, a plastic barrier in the walls (damp course layer) is used to prevent bricks from absorbing moisture in modern constructions, while for condensation it is important to reduce humidity levels in your home through ventilation or dehumidifiers.
