Troubleshooting Dampness in a Home Renovation

Dampness within a building can cause many issues – including a build-up of mould (creating health problems) and defects (structural problems).

If you’ve been called in to inspect or renovate a building that has damp patches and stains, then it is useful to know what some of the common causes for dampness are and where to focus your repairs and building material replacements.

If there are patches of moisture in central ceiling area, the most likely culprit is leaking pipes. A plumber will be needed to fix/replace the pipe system.

If the patches are on a top floor level it could also be a roof leak. Then tile repair work is necessary.

If there are damp patches around the ceiling and chimney area this may be a result of a gap in flashing around the chimney. Inspect the area and repair if needed.

If dampness is apparent at wall and ceiling junctions (on a top floor level) this most often the result of a blocked gutter. Unblock the gutter. A lean-to building, where the flashing (at the point where it joins the main building) has deteriorated, can also create this problem. Check the flashing and repair if necessary.

Elongated damp patches along internal corners often indicate a blocked or cracked downpipe on the exterior of the building. It allows dripping water to gradually penetrate and create a damp wall stain. Unblock or replace the downpipe (as required).

You’ll find that dampness is common around the edges of windows (window frames). This is due to condensation build-up or because of a break in the seal around the edge of the window frame. Check that the window is sealed correctly and re-apply silicone sealant if needed. If the problem is due to the conditions within the room, ie. water vapour, then it might be necessary to install a more effective ventilation system.

If the dampness appears below the window, it’s possible that the seals beneath window may be damaged, or the drip guard below the sill is blocked. Check for both and clear or re-seal as needed.

If large damp patches appear above the skirting this is often a result of a build-up of material on the external side of the wall surface, ie. soil, garbage, etc. This build-up bridges the damp course and causes moisture to penetrate. Remove the obstructive material.

Disused chimneys where the chimney and fireplace have been blocked off are notorious for developing damp patches around the central chimney breast. The reason is there is no ventilation, causing the moist damp air to penetrate through the chimney breast. A solution is to install an air vent in the chimney breast. This will improve air flow.

Tide marks above skirting can be damp course being bridged on the other side of the wall or rising damp. This is a common occurrence in older dwellings with no damp course or where the damp course has been damaged and allows water penetration. The most effective solution is a damp-proofing injection systems.

Small damp patches in interior corners of the walls are often a result of damaged pointing or render on the exterior of the building. Repair the damaged building material.

Drip stains or running moisture stains on walls indicate a condensation problem. This is why they are common in kitchens, bathrooms and laundries.  Install ventilation systems.