Your Neighbours Can See the Flaking
That patch under the bedroom window has been bothering you since last autumn. The paint started lifting at the edges, then a whole strip curled away after the January frost, and now there's bare render showing through in two places. You've been telling yourself it's cosmetic. It isn't. Exposed masonry absorbs moisture, and moisture in walls leads to damp indoors, higher heating bills, and eventually structural damage that costs far more than a few tins of Dulux Weathershield.
Exterior painting is one of those jobs that rewards thorough preparation and punishes shortcuts. Get the prep right and a single coat system can last eight to ten years. Rush it — paint over flaking surfaces, skip the primer, work in the wrong weather — and you'll be back on the ladder within three seasons. The good news is that a typical three-bedroom semi can be done over a long weekend if you plan properly, and the materials will cost somewhere between £150 and £400 depending on the products you choose.
When to Paint: The Weather Window
Exterior masonry paint needs dry, mild conditions to cure properly. The sweet spot is late April through September, with daytime temperatures above 10°C and no rain forecast for at least 24 hours after application. Most manufacturers — Dulux, Sandtex, Johnstone's — specify a minimum of 5°C, but performance drops noticeably below 10°C because the paint film takes longer to coalesce and is vulnerable to overnight dew before it's fully cured.
Wind matters too. A gentle breeze helps drying, but anything above about 15 mph will cause the paint to skin over too quickly on the surface while remaining soft underneath. That leads to cracking within months. If you're working on a south-facing wall in July, the opposite problem applies: direct sun heats the surface and the paint dries before it has time to level out, leaving brush marks and roller texture that you won't shift without sanding back. Paint south-facing elevations early in the morning or wait for a cloudy day.
Check the BBC Weather hourly forecast the evening before each day of painting. Dew point matters — if the air temperature is likely to drop within 3°C of the dew point overnight, moisture will condense on your fresh paint. This is the single biggest reason exterior paint fails prematurely in the UK, and most DIYers never think about it.
Tools and Materials: What You Actually Need
Buy these before you start. Running to B&Q mid-job because you forgot masking tape wastes an hour and breaks your rhythm.
- Exterior masonry paint — Dulux Weathershield (around £38 for 5L at Screwfix) is the standard choice and performs well. Sandtex Ultra Smooth is slightly cheaper at roughly £32 for 5L and covers marginally better on rough render. For a premium option, Zinsser AllCoat Exterior (about £55 for 5L) offers excellent adhesion on previously painted surfaces and dries in two hours.
- Stabilising solution — essential if any existing paint is powdery or chalky. Leyland or Johnstone's stabilising solution runs about £12–£15 for 5L. Brush or roll it on and let it dry for 24 hours before painting.
- Filler — Everbuild 210 Powder or a premixed exterior filler for cracks wider than a hairline. About £8–£12 per tub.
- Masking tape and dust sheets — Frog Tape for clean lines around windows and doors (£6–£9 per roll). Cheap poly dust sheets from Screwfix are fine for the ground, around £3 for a pack of three.
- A 12mm medium-pile roller sleeve (not a foam one — they leave bubbles on textured render), a roller frame, an extension pole, a 2-inch angled brush for cutting in around windows, and a wire brush for scraping.
- A pressure washer or garden hose with a jet nozzle — you almost certainly own one already.
For a standard three-bed semi with about 80–100 m² of paintable wall, budget for 10–15 litres of masonry paint. Two coats is non-negotiable, and coverage on rough render is typically 6–8 m² per litre rather than the 12–14 m² the tin claims.
Preparation: Where 80% of the Job Happens
If you do nothing else, do the prep properly. A beautifully applied top coat over a poorly prepared surface will fail within two years. An average top coat over immaculate prep will last a decade.
Cleaning
Start with a pressure washer on a medium setting — around 100–120 bar is enough for render without blasting it off. Work from top to bottom, overlapping your passes. You're removing dirt, algae, moss, and any loose or flaking paint. Pay particular attention to north-facing walls and areas under eaves where green algae tends to build up. If there's significant green or black biological growth, treat the wall with a fungicidal wash (Algon Organic Path Cleaner works on render too, about £15 for 2.5L concentrate) and leave it for 48 hours before washing off.
After washing, the wall needs to dry completely. In summer, 24–48 hours is usually sufficient. In spring or autumn, give it a full 72 hours. Touch the surface — if it feels cold or clammy compared to a dry interior wall, it's not ready. Painting over a damp wall is the fastest way to guarantee peeling within six months.
Scraping and Filling
Once the wall is dry, run your hand firmly across every surface. Anywhere the existing paint feels loose, powdery, or lifts under fingernail pressure needs to come off. Use a wide scraper or wire brush. You're not trying to strip back to bare render everywhere — just remove anything that isn't firmly bonded. Where you've scraped back to bare substrate, those areas need a coat of stabilising solution before anything else goes on.
Fill any cracks wider than about 1mm with exterior filler, pressing it in firmly with a filling knife and leaving it slightly proud of the surface. Once set (usually 2–4 hours depending on the product), sand it flush with 80-grit paper on a block. Hairline cracks in render are normal and the paint will bridge them — don't obsess over filling every tiny line or you'll be at it for days. Cracks wider than about 5mm or cracks that appear structural (diagonal cracks from corners of windows, for instance) need investigating before you paint over them. A structural crack disguised with filler and fresh paint is a nasty surprise for whoever discovers it next, whether that's you or a surveyor.
Masking
Tape off window frames, door frames, and any plastic or metal fittings you don't want paint on. This takes about an hour for a whole house and saves three hours of touch-up work with white spirit afterwards. Press the tape edges down firmly — if paint bleeds under the tape, you haven't pressed it properly. Remove the tape while the final coat is still slightly tacky for the cleanest edge.
Choosing Your Colour: Practicality Over Pinterest
A word on colour before you start. Brilliant white is the UK default for a reason — it's the cheapest to buy, the easiest to touch up in future years, and it makes a house look clean and well-maintained. But it shows dirt fastest, particularly on a house near a busy road or under trees. Off-white shades like Dulux Jasmine White or Sandtex Magnolia are only marginally more expensive and stay cleaner-looking for significantly longer.
If you want actual colour — a grey, a sage green, a warm cream — go for it, but test a sample pot on a 1m² patch first and live with it for at least a week. Colours look completely different on a vertical exterior surface under natural light compared to a swatch card held under a kitchen spotlight. Dulux Weathershield has a reasonable range of ready-mixed colours; Sandtex is more limited. Both offer a colour-matching service at B&Q and Wickes for around £5–£8 extra per tin, which is worth it if you want something specific. Bear in mind that some conservation areas and listed properties have restrictions on exterior colour — check with your local council planning department before committing to anything unconventional. That dark charcoal grey that looks stunning on a new-build might land you an enforcement notice on a Victorian terrace in a conservation zone.
The Weekend Plan: Friday Evening to Sunday Afternoon
Friday Evening (1–2 Hours)
Set up your work area. Lay dust sheets along the base of the walls. Move any garden furniture, bins, or planters at least two metres away from the house — paint mist carries further than you'd think. Mask all windows and doors. Mix your paint thoroughly with a flat stirring stick — masonry paint settles in the tin and the pigment concentrates at the bottom. If it's not fully mixed, you'll get colour variation across the wall. Pour enough for the first section into a roller tray and seal the tin to prevent a skin forming overnight.
Saturday Morning (3–4 Hours): First Coat
Start early — 7 or 8 a.m. if your neighbours won't mind the ladder noise. Cut in around all windows, doors, and edges with the angled brush first. This is the slow, careful bit. Load the brush about a third of the way up the bristles, tap off excess on the edge of the tin, and work in smooth overlapping strokes. Don't try to stretch the paint too far — a thin coat peels; a proper coat lasts.
Once cutting in is done, switch to the roller on the extension pole for the main wall areas. Work in W-shaped passes about 1m² at a time, then go back over the section with light, even vertical strokes to smooth out the roller marks. Keep a wet edge — if you let one section dry before the adjacent section is rolled, you'll get a visible overlap line called a lap mark. On a hot day, work fast and do one complete wall at a time. On a cool day, you have more working time and can be more methodical.
First coat done by lunchtime. Clean your roller sleeve and brush immediately — dried masonry paint is nearly impossible to remove. Wrap them tightly in cling film if you want to skip cleaning and reuse them for the second coat the next morning.
Saturday Afternoon: Rest and Inspect
Leave the first coat alone. Resist the urge to touch it. Go and do something else for at least six hours — most masonry paints specify a recoat time of four to six hours, but longer is better. In the late afternoon, walk around and inspect. Mark any areas where the coverage looks thin (you'll see the old colour ghosting through) or where you've missed a spot. These areas get an extra pass during the second coat.
Sunday Morning (3–4 Hours): Second Coat and Finish
Same process as Saturday. Cut in, then roll. The second coat goes faster because the first coat has sealed the surface and you're not fighting absorption. Pay extra attention to the areas you marked yesterday. When the second coat is complete, carefully remove all masking tape while the paint is still slightly tacky — pulling tape off fully dried paint can lift the edge. Fold the dust sheets inward to trap any paint drips, and move your furniture back once you're confident the walls are dry to the touch.
Total active painting time: roughly 8–10 hours across the weekend. Total materials cost for a three-bed semi: £200–£350 including everything from paint to masking tape. A professional painter would charge £800–£1,500 for the same job, so the saving is real — but only if you do the prep properly and use decent products. Cheap paint from the bargain bin is a false economy; it fades, chalks, and peels in half the time.
What About Woodwork?
While you've got the ladders up, it's tempting to paint the fascias, soffits, and bargeboards at the same time. This makes sense logistically, but don't use masonry paint on wood — it won't flex with the timber and will crack. Use a dedicated exterior wood paint like Dulux Weathershield Exterior Gloss or Ronseal 10 Year Weatherproof Wood Paint (around £22–£28 for 2.5L). Sand the wood lightly with 120-grit first, apply a coat of exterior primer-undercoat to any bare patches, then two coats of your chosen finish. The sanding is critical — gloss over old gloss without keying the surface will peel within a year, guaranteed.
If your fascias and soffits are uPVC rather than timber, leave them alone. A wipe down with sugar soap is all they need. Painting uPVC is possible with specialist products like Zinsser AllCoat, but the finish never looks as good as the original factory coating and it adds a maintenance cycle that uPVC was specifically designed to eliminate.
Common Mistakes That Ruin the Job
Painting in rain or when rain is forecast within 12 hours. The label says 4 hours to rainproof; in practice, give it overnight. A single heavy shower on uncured masonry paint will wash the surface binder out and leave you with a chalky, powdery finish that needs stripping off and starting again. Skipping the stabilising solution on chalky surfaces is the second most common failure — the fresh paint bonds to the powder layer, not the wall, and the whole lot comes off together like sunburned skin.
Overloading the roller is another classic. Too much paint causes runs and drips that set hard and look awful. Two thin coats always beat one thick coat. And finally, painting in temperatures below 5°C or above 30°C. Both extremes prevent proper film formation. If you're watching the thermometer drop on a late September evening and thinking about squeezing in one more wall — don't. Come back next weekend or wait until spring. The paint will still be in the tin.
Store any leftover paint sealed tightly in a cool, dry place — a garage shelf is ideal. Masonry paint keeps for two to three years in an unopened tin and at least a year once opened, provided no skin has formed. Label the tin with the colour name, the date, and which walls it went on. Your future self will thank you when a section needs touching up after a harsh winter.