Most people who ask us whether they should paint their roof are really asking one of two things. Either the roof looks tired and they want it to look better, or they are worried about it and hope paint will make it last longer. Paint does the first job well. It does the second one far less than the brochures suggest. The short answer is that painting is worth it on a sound concrete tile, fibre cement or metal roof that has faded, and it is a waste of money, or worse, on a roof that has a problem underneath. Here is how to tell which one you have.
What paint actually does to a roof
A roof keeps water out because of the way the tiles or slates overlap and the membrane under them, not because of the surface of the tile. Paint sits on that surface. On a concrete tile that has weathered for twenty or thirty years, the face has gone porous and chalky, it holds water and grows moss quickly, and the colour has washed out to a patchy grey. A proper cleaning, a biocide, a primer and two coats of roof paint seal that face again, bring the colour back and slow the moss down for a good number of years. That is a real improvement and on the right roof it is money well spent.
What paint does not do is fix a cracked tile, re-bed a loose ridge, replace a perished underlay or stop a leak at a valley or a chimney. If any of those are behind the reason you are looking at the roof, painting over them hides the problem for a season and makes it harder to spot later.
Roofs where painting makes sense
- Concrete tiles that are faded, mossy and porous but still solid, sitting straight and not cracking when walked on by someone who knows how. This is the most common case in Ireland and the one where paint gives the best return.
- Fibre cement slates of the modern, asbestos free type, where the colour has gone and the surface has roughened, but the slates are still fixed and flat.
- Metal roofs and cladding on sheds, garages and farm buildings, where surface rust is starting. Here paint genuinely protects the material, provided the rust is treated first and not just painted over.
- A house going on the market, where the roof is sound and a fresh colour changes how the whole front looks from the road.
Roofs you should not paint
Natural slate
Do not paint a natural slate roof. Slate does not fade or go porous the way concrete does, so there is nothing for the paint to improve, and a painted slate roof cannot easily be put back. If a slate roof looks bad it is usually because of slipped or broken slates, moss in the laps or a tired ridge, and those are repairs. See slate replacement.
Clay tiles
Clay tiles hold their colour for decades and weather in a way most people like. Paint rarely bonds well to them over time and it takes away the one thing clay has going for it. Clean them, replace the broken ones and leave them alone.
Older fibre cement slates
Fibre cement slates fitted before the early 2000s can contain asbestos. They must not be pressure washed or scraped, because that releases fibres. If your house was built or reroofed in that era, have the slates assessed before anyone goes near them with a washer. Sometimes the answer is to leave them undisturbed, and sometimes it is replacement by a licensed contractor, but it is never a quick clean and paint.
A roof that is near the end of its life
If tiles crack when they are stepped on, the roof line has started to dip, there are damp patches in the attic or the felt under the tiles has gone brittle, the roof is telling you it needs work, not colour. Paint on a failing roof is money spent twice, because it all comes off with the tiles when the roof is done. Start with roof repair or tile replacement and decide about paint afterwards.
The mistake that turns a paint job into a leak
Tiles and slates are designed to let water that gets under them drain away and to let the roof breathe. Some cheap spray jobs coat the roof so heavily that the paint bridges the gaps where the tiles overlap. Water that gets in through a crack or under a ridge can then no longer run out, it sits behind the paint and ends up in the timbers. A good roof painter keeps the laps open, uses a breathable roof paint made for the material, and repairs every broken tile before the first coat goes on. If a quote promises that a coating will make your roof waterproof for twenty years, treat it with suspicion. We go through the difference between paint and coating in more detail on roof coating.
What about a flat roof?
People often ask whether they can paint the flat roof over an extension or garage while they are at it. Ordinary roof paint is not the answer there. A flat roof has no overlaps to shed water, so its surface is the waterproofing, and a coat of paint on tired felt only buys a few months. If the deck underneath is still firm and dry, the better option is a proper liquid applied membrane laid over the existing roof, such as Lava 20, which is reinforced at every upstand and outlet and saves stripping the old roof off. If the deck is soft or the insulation is wet, it has to come out first, whatever goes on top.
Irish weather and timing
Roof paint needs a dry roof, mild temperatures and a clear spell after it goes on so it can cure before rain or a heavy dew. In Ireland that realistically means late spring to early autumn, and on the west coast even the summer needs watching. The roof also has to dry out properly after it is washed, which can take a day or two on its own. By the end of September the window is closing, so if you are thinking about it now, the sensible move is to have the roof looked at and any repairs done before winter, and book the painting for spring. Our winter roof preparation check covers exactly that.
How long it lasts, and whether it is worth it
A properly prepared and painted concrete tile roof will usually look good for around ten years, sometimes more on a sheltered site, less on an exposed one facing the Atlantic. After that it will need a clean and possibly a fresh coat. Compared with replacing the roof, painting costs a fraction, so on a sound roof that you plan to live under for a while it is a reasonable investment in appearance and in slowing the moss and weathering down. On a roof that will need replacing within a few years anyway, it is better to put that money towards the new roof.
One more thing to check before you change the colour. For most houses repainting a roof is ordinary maintenance, but if your house is a protected structure or sits in an architectural conservation area, a change of roof colour or finish may need planning permission. Ask your local council before you pick a new colour.
A quick way to decide
- Concrete tile, fibre cement or metal, faded but sound: painting is worth considering.
- Natural slate or clay: do not paint, repair and clean instead.
- Fibre cement from before the 2000s: get it assessed first, do not wash it.
- Cracked tiles, sagging, leaks or damp in the attic: repair first, paint only if the roof is sound afterwards.
- Late in the season: get the survey and repairs done now, paint in spring.
If you are not sure which of these describes your roof, send us a couple of photos from the ground and one from inside the attic. We work across Kerry, Cork and Limerick and we will tell you honestly whether painting is worth it, whether it needs a repair first, or whether it is better left as it is. Email info@althome.ie or ring 085 220 1422, and see roof painting for how we do the job.