The Risks of Rising Damp in Buildings and What to Do About It

by | May 17, 2018 | Home

Rising damp is the upward flow of moisture via a permeable wall building, the moisture originating from groundwater. This moisture rises typically through the capillaries or pores in the building materials by a process known as capillarity, which makes the masonry to behave like a wick.

Rising damp often varies in severity contingent on various factors including the structure of pores in the masonry materials, the rate of evaporation past the wall surface and the level of groundwater. It often needs treatment since it has numerous undesirable outcomes on the performance of stone buildings, including:

Building Fabric Erosion

The ground salts brought about by rising damp to the wall can attack and also dissolve the binders found in the stone, mortar, and brick making them lose their structural integrity and strength. Crystalizing salts can also exert similar forces causing them to destroy the microstructure of the stone, brick or mortar.

Increased Heat Loss

Any dampness in permeable building materials leads to a reduction of the insulation properties because the air found in the pores often get replaced by water that’s more conductive. For instance, a wet brick’s conductivity is roughly twice that of a dry one.

Decorative Spoiling

The ground salts and moisture brought about by rising damp in buildings can cause plaster to deteriorate, paint to blister, and wallpaper to peel.

Health Effects

Currently, it has been extensively documented that too much dampness in buildings has lots of negative impacts on the health of the occupants of the building.

How to Control Rising Damp in Buildings

Protect and Repair Walls

Re-point deeply corroded mortar joints in the walls. While cement is suitable for modern-day buildings, it’s vital to utilise a lime or sand mix for most buildings dating back to 1900. Focused re-pointing is usually all that is needed. Ships caulking, lime mortar and Daub, are suitable for closing any gaps that might develop around the borders of panel infillings in the timber-framed structures.

Where rain enters an exposed west and south-facing wall, lime renders, lime wash and tile or slate hangings are traditional resolutions although you cannot use them without changing the wall’s external appearance. Sometimes, installing a dry ventilated lining system inside is appropriate. Using plastic-based paints or colourless water-repellent treatments is strongly inadvisable.

Repair and Maintain Your Roof

Replace missing and dislodged tiles and slates before damage occurs to your plaster ceilings or roof timbers. Brush moss from your roofs because it can block the gutters and retain dampness, which can damage some roof coverings in cold weather. Also, clear rainwater pipes and gutters regularly, mostly if your building is perched on by suckers or surrounded by trees. You should clear snow from the valley and parapet gutters to prevent the melt-water from rising over them and triggering dampness internally.

Internal Finishes

To reduce the risk of any future problems, you should use lime plaster for any re-plastering instead of the renovating or anti- sulphate plasters favoured mostly by many treatment firms. Decorating with paints like soft distemper and lime wash where possible will increase breathability. Joinery old items removed during the work should be repaired and reinstated carefully, not automatically replaced.

Controlling Underground Dampness

To achieve the best rising damp treatment, you should take measures that assist your building in breathing. Pointing using a suitable lime-based mortar or replacing a hard cement render usually improves a wet wall and also enables the rising moisture to dry out. On the other hand, the application of bituminous coatings and waterproof renders tends to start or worsen damp problems.

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