How do I clean and repaint fascias and soffits?

Preparing timber and uPVC fascias for coating, the paint systems that survive at eaves level, and knowing when repainting is not the answer.

Difficulty: intermediate
Time: 8 hr
Read: 4 min
Safety: warning

Short answer

Wash, dry, and check the timber is sound — anything soft has to be cut out or spliced before painting. Prime bare timber, use a flexible exterior wood paint or a microporous system, and paint the underside and the back edges as well as the face.

Fascias and soffits are the most exposed painted timber on a house. They face upwards and outwards, they are shaded and slow to dry, and the back face is almost never painted, which is why they rot from behind while the front still looks acceptable.

Safety

This is sustained work at eaves height and it is a common cause of falls. A tower or a hop-up scaffold is far safer than a ladder for a job that needs both hands and takes hours. Never overreach from a ladder. Paint stripping on a house built before about 1980 may disturb lead paint — do not dry-sand or heat-strip it without testing; use a lead paint test kit and a chemical stripper with the correct precautions. If the eaves are above single-storey height, get a contractor.

Step by step

Set up safe access first.This is hours of two-handed work at height. A tower or a scaffold is worth hiring; a ladder is not adequate for the preparation stage of a full elevation.
Wash everything down.A detergent or fungicidal wash, brushed on and rinsed, removes the algae and the airborne grime that stops paint adhering. Let it dry completely — usually a couple of dry days.
Test for rot before painting anything.Push a bradawl into the timber at joints, at the ends, and behind the gutter. Anything soft is rot, and painting over it just hides it. Cut out and splice or replace those sections first.
Check for lead paint on older houses.Pre-1980 paint may contain lead. A test kit costs a few pounds. If it is positive, do not sand or heat strip — use a chemical stripper with full precautions, or overcoat rather than strip.
Prepare the surface properly.Scrape off loose and flaking paint, sand back the edges so there is no ridge, and key the sound paint. Fill splits and nail holes with an exterior grade filler.
Prime and knot bare timber.Knotting solution on any knots, then an exterior wood primer on all bare areas. Bare timber left unprimed under a topcoat is where the next failure starts.
Paint the back and underside too.The reason fascias rot is that the hidden faces are unpainted and stay wet. Get paint behind the top edge and along the underside as far as you can reach, even if nobody will see it.
Use two topcoats of a flexible exterior paint.A microporous exterior wood paint or a good flexible gloss system. Two thin coats, allowing full drying between. Thick coats skin over and stay soft underneath.
Clean uPVC rather than painting it.A dedicated uPVC cleaner or a mild cream cleaner removes most weathering. Specialist uPVC paint exists and works, but it needs a solvent wipe and a proper primer and it will need redoing.
Seal the joints and the gutter line.A flexible exterior sealant at the joint between fascia and soffit, and where the fascia meets the wall, keeps water out of the end grain.

Tips

Paint on a dry day with a dry forecast, and stop well before dew starts to fall — evening damp on fresh paint causes blooming.
Take the gutter down if it is coming off anyway. Painting behind a fitted gutter is very awkward and it is where the rot starts.
Work along the elevation rather than up and down. Keeping a wet edge along the fascia gives a much better finish.

Common mistakes

Painting over soft or rotten timber — The paint holds the moisture in and the rot continues underneath. Within a couple of years the paint blisters and the timber underneath has gone. Cut out rot before painting.
Painting only the visible face — The unpainted top edge and back face take up water and the board rots from behind. Getting paint onto the hidden faces is what makes the job last.

If it doesn't work

Paint blistering within a year

Cause: Painted over damp or rotten timber — Fix: Strip back to bare timber, check for rot, let it dry thoroughly, prime and repaint.

Black staining reappearing quickly

Cause: Algae growth in a damp shaded position — Fix: Use a fungicidal wash before painting and consider a paint with a fungicide. Cutting back overhanging vegetation helps more than the paint does.

Bare timber showing at the joints

Cause: Movement in the joint opening the paint film — Fix: Fill with a flexible exterior sealant rather than a rigid filler, then prime and paint.

uPVC fascia looking chalky and faded

Cause: UV degradation of the surface — Fix: A uPVC restorer cream often brings it back. Painting is possible but is a commitment to repainting periodically.

Questions people ask

Can I paint uPVC fascias?

Yes, with a solvent wipe, the correct adhesion primer and a paint made for uPVC. It works well but it is no longer maintenance-free — you have signed up to repainting every five to ten years.

How often do timber fascias need repainting?

Every four to six years on a sheltered elevation, less on an exposed one. The tell is when the finish loses its sheen and starts to go chalky — recoating then is far easier than after it has cracked.