Scraped render is a thick, mineral, water-repellent render whose top layer is partly scraped away once it has set. That leaves a rough, evenly textured surface in which the aggregate — the grains — is exposed. The texture is granular and looks like a coarse decorative render.
Where it is used
Scraped render can be used inside and out, but it is mostly applied to external walls. It comes in a range of colours and can be through-coloured or painted afterwards. Through-coloured has a practical advantage: damage or a later repair shows up far less than on a painted finish.
How it is applied
- Prepare the background. It must be sound, clean, load-bearing and reasonably flat. Remove loose material and old paint; on a strongly absorbent or mixed background, apply a primer or a base coat first.
- Apply the full thickness. The coat must be at least thick enough for the aggregate to be fully embedded — so the grain size sets the thickness. Applied too thin, scraping pulls the grains out.
- Let it set. This is the critical moment: scrape too early and the render smears, too late and it will not come off at all. The right time depends on product, temperature, wind and sun; the manufacturer gives a working window — always check on a trial area.
- Scrape it back. With a scraping float or nail board across the whole area, in an even motion. Then brush off the loosened material.
Points to watch
- Work area by area, wet on wet. A wall left half finished shows a join line that cannot be worked out afterwards. Split the work at natural breaks (corners, movement joints, windows).
- Not in full sun or in frost. Drying too fast gives shrinkage cracks and a weak surface; frost while it is setting destroys the bond.
- Shed water at the top. All external render needs a proper coping with an overhang and a drip; water running in over the top is the most common cause of failure.
- Allow for soiling. A rough surface collects more dust and algae than a smooth one, particularly on the north side and under overhangs.
Related terms
- Decorative render
- Base coat
- Rendering
- Facade finish
- Shrinkage crack
- Primer
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