Issues and repairs | BRANZ Maintaining My Home

Soffits – mould and lichen

Listed under: Exterior, walls, moisture, leaks, mould, soffits

wash the soffit with warm water and detergent and a soft broom or use a proprietary anti-mould cleaner
do not use a high-pressure water blaster as this can damage the surface or force water into the roof space or wall space through cracks or gaps
if the paint coating has been damaged, leave the soffit to dry thoroughly. Once dry, sand or gently scrape away any loose paint. Ensure the surface is clean and smooth and then recoat with 2 coats of good quality paint. Major paint manufacturers have specialised paints with stain blockers and mould inhibitors, for use where mould or stains have occurred. If water stains are present on materials and the material is painted with an ordinary water-based paint, the stain will usually bleed through the new coating
begin a regular cleaning routine, annually or more frequently as required
if the soffit is damp because of trees close to the house, trim back the branches to allow good air circulation
safety is a prime consideration when working at height. Find information here about using ladders and scaffolding safely. Always let someone know when you plan to work at height

the first task will be to determine the source of the leak. (Many of the problems described here have repairs given on other pages of this website.) Potential causes can include:

rainwater from exterior guttering overflowing into the soffit. It could be blocked outlets or downpipes, insufficient fall (slope) in the gutter, or a lack of a gap between the gutter and the fascia board
the bottom edge of roof cladding not extending far enough over the gutteringc
a leak in the roof cladding
a leak in a roof cladding flashing or penetration flashing
a leak from a water pipe in the roof space

if you have trouble finding the cause, consult an experienced building surveyor for advice
once the cause has been addressed, leave the soffit to dry thoroughly. Once dry, sand or gently scrape away any loose paint. Ensure the surface is clean and smooth and then recoat with 2 coats of good quality paint. Major paint manufacturers have specialised paints with stain blockers and mould inhibitors, for use where mould or stains have occurred. If water stains are present on materials and the material is painted with an ordinary water-based paint, the stain will usually bleed through the new coating
safety is a prime consideration when working at height. Find information here about using ladders and scaffolding safely. Always let someone know when you plan to work at height