Summary
Render repair is one of those jobs where the materials are cheap, the labour is moderate, and the scaffold blows the budget. A customer rings up about a 1m² blown patch on a gable, expecting £150 because they've seen a bag of render at the merchants for £8. The reality is that to do the job safely and properly you need either a tower scaffold (£150–£300 hire for a few days) or a section of system scaffold (£400–£1,200 for a small gable), plus 1–2 days of a plasterer's time, plus paint to match. The "£8 of materials" is the smallest part of the quote.
The other thing that catches tradespeople out is misdiagnosis. Blown render almost never fails on its own — it fails because of damp ingress behind it, movement in the substrate, the wrong mix used originally (too strong a sand-cement on a soft brick), or freeze-thaw damage at parapet/sill level. Patching without understanding why it failed means the patch will fail again within 2–5 years and the customer will blame the tradesperson. A good quote includes a brief inspection note covering likely cause and what's needed to stop recurrence (replace cracked sill, re-bed loose coping, fit new lead flashing, install cavity tray, etc.).
This guide covers patch and small-area repair pricing. For full re-rendering of an entire property, see external render pricing guide.
Key Facts
- Sand-cement render (traditional 3-coat) — scratch coat 1:3 cement:sand + plasticiser, float coat 1:4:1 cement:sand:lime, finish coat 1:5:1 or 1:6:1; total thickness 18–22mm; ~£8–£14/m² in materials
- Lime render (NHL 3.5) — single bag NHL 3.5 hydraulic lime + sharp sand 1:2.5; required on solid-wall pre-1919 properties to allow vapour movement; ~£18–£32/m² in materials
- Silicone/acrylic thin-coat (monocouche) — proprietary one or two-coat system (Weber, Parex, K-Rend, Krend Silicone TC, Marmorit); typically 6–15mm total; ~£18–£35/m² in materials
- Lath and EPS substrate (warm render) — over external wall insulation (EWI); not for repair, only full systems
- Plasterer day rate (renderer) — £280–£400/day regional, £350–£500/day London (2026 rates)
- Coverage per m² (sand-cement) — ~25kg/m² for 15mm thickness across all 3 coats
- Coverage per m² (monocouche silicone) — ~17–22kg/m² for 10–15mm two-coat
- Drying time between coats (sand-cement) — 24–48 hrs minimum; 7 days before paint
- Drying time (monocouche) — base coat to topcoat 4–24 hrs same day; rain-resistant in 4–6 hrs
- BS EN 13914-1:2016 — Design of external rendering
- BS EN 13914-2:2016 — Application of external rendering
- NHBC Chapter 6.11 — External rendering for new build (mandatory on NHBC sites)
- PD 6697 — General code for masonry; covers movement joints and substrate compatibility
- Movement joints required — every 5–6m horizontally and 5–6m vertically per BS EN 13914-1
- Mesh reinforcement — fibreglass mesh embedded in base coat at junctions, openings, and over dissimilar substrates (always for monocouche over block + brick joints)
- Bell-cast/drip bead — required at base of render run (above DPC, above openings) per BS EN 13914-1
- Suction control — high-suction backgrounds (engineering brick, old hard render) need SBR slurry or proprietary primer before render
- Scaffold per week — tower £80–£180/week; gable system scaffold £400–£900/week; full elevation £900–£2,200/week
- Frost rule — never render below 5°C ambient or onto frozen substrate (BS EN 13914-2); plan around weather
Quick Reference Table
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Try squote free →| Job | Area | Labour time | Typical price (2026) |
|---|---|---|---|
| Single hairline crack repair (raked + re-pointed render) | <1m linear | 1 hr | £80–£180 |
| Small patch repair (one blown panel) | 1–2m² | 4–6 hrs + return for finish | £180–£400 |
| Window/door reveal re-render | 2–4m² | 1 day | £350–£650 |
| Sill or threshold area patch | 1–2m² | 4–8 hrs | £200–£450 |
| Gable patch (multiple blown areas) | 5–10m² | 2–3 days + tower scaffold | £600–£1,400 |
| Bay window full re-render | 8–12m² | 2–3 days + tower scaffold | £900–£1,800 |
| Single elevation re-render (semi side wall) | 20–30m² | 5–7 days + system scaffold | £2,200–£4,500 |
| Full elevation re-render (front of semi) | 40–60m² | 7–12 days + system scaffold | £3,500–£7,500 |
| Material cost item | Typical 2026 cost |
|---|---|
| OPC (cement) 25kg | £6–£10 |
| Plastering sand 25kg | £4–£8 |
| Hydrated lime 25kg | £10–£18 |
| NHL 3.5 hydraulic lime 25kg | £14–£22 |
| Plasticiser (Febmix etc.) 5L | £14–£22 |
| Monocouche silicone topcoat 25kg | £28–£55 |
| K-Rend / Weber base coat 25kg | £18–£28 |
| Fibreglass render mesh roll | £25–£55 |
| PVC bell-cast / stop bead 2.5m | £6–£14 |
| SBR slurry 5L | £18–£30 |
| Masonry paint 5L (Sandtex, Dulux Weathershield) | £35–£75 |
Detailed Guidance
Diagnose before you quote
Render fails for one of six reasons. Identify which one — or don't quote until you have. Repairing a blown patch without addressing the cause is throwing money at a symptom.
- Damp ingress from above — failed coping, missing flashing, broken gutter; render at top of wall blows first, then water tracks down
- Damp from below — bridged DPC, render carried down past DPC level (must stop 150mm above with bell-cast); always check the bottom 300mm
- Substrate movement — vertical cracks at openings, settlement cracks across the elevation; render is following structural movement
- Wrong mix — strong sand-cement (1:3) over soft brick or AAC block; rigid render cracks the brick; common on 1950s–80s housing
- Freeze-thaw — render saturated by overflow gutter or splashback then freezes; spalls off in plates
- Original poor application — too thick, too fast, no scratch coat, no mesh; just falls off
Write the cause in the quote: "Cause: failed cill apron under bedroom window allowing water behind render. Recommend re-bed cill on lead apron before repair, otherwise repair will fail within 2 winters."
Sand-cement vs lime vs monocouche — when to use which
Sand-cement (modern 3-coat) — Standard for cavity-walled houses post-1930. Good on common brick, dense block, concrete. Strong (10–15 N/mm²), durable, cheap. NOT for solid-wall pre-1919 properties (too rigid, traps damp).
Lime render (NHL or putty lime) — Required on solid-wall pre-1919, listed buildings, conservation areas. Vapour-permeable, flexible. Slow to set, must be lime-watered, weather-sensitive. Much higher labour skill premium.
Silicone/acrylic monocouche — Pre-coloured (no paint required), water-repellent, breathable, faster application. Good for new build, full re-renders, and customers who don't want to repaint every 7 years. Cost more per kg but go on thinner.
Pebbledash, roughcast, Tyrolean — Specialist finishes; patch matching is the hard part — texture and aggregate colour are almost impossible to replicate exactly on a small patch.
Procedure for a typical patch repair
For a 2m² blown patch on a sand-cement gable:
- Erect access — tower scaffold or ladder per height; never reach over from a ladder for plastering work (Work at Height Regs 2005)
- Hack off all loose render — back to substrate, going 100–150mm beyond the visible failure into sound render
- Diamond-cut the perimeter — straight saw cut 5–10mm deep gives a clean square edge to render to
- Brush off all dust, wet down substrate — control suction
- Apply SBR slurry coat if high-suction or low-key substrate
- Scratch coat (1:3 cement:sand + plasticiser) — 6–10mm thick, scratched with comb scratcher for key
- Wait 24 hrs minimum (longer in cold/damp)
- Float coat (1:4:1 cement:sand:lime) — 8–12mm, ruled flat with feather edge, sponge floated
- Wait 24–48 hrs
- Finish coat (1:5:1 or 1:6:1) — 2–4mm, sponge or wood float finish to match existing texture
- Wait 7 days minimum before painting (longer in winter)
- Paint with masonry paint — match existing colour; whole elevation paint is often needed for visual match (price separately)
A patch is rarely invisible — the customer needs to be told that a colour difference at the patch line is normal until the whole wall is repainted.
Common pitfalls
- Quoting paint as included when it isn't — always specify "patch repair finished; masonry paint to elevation by customer or quoted separately"
- No bell-cast at base of new render — water tracks down behind, blows render at DPC in 2 years
- Skipping mesh at substrate transitions — brick/block joints, repair-to-existing junctions all crack without 150mm fibreglass mesh
- Working in frost or below 5°C — render fails to gain strength; spalls off the next winter
- Strong mix over soft brick — cracks the brick, not the render; permanent damage
- Forgetting the scaffold weekly hire when the job overruns — scaffold is by the week; a 3-day job that runs to 8 days costs you a week extra hire
Pricing breakdown for a typical job
A typical gable patch (8m² over 4 separate blown areas, requires tower scaffold + 2.5 days plasterer + repaint of gable):
| Item | Cost |
|---|---|
| Tower scaffold hire 1 week | £180 |
| Tower delivery + collection | £80 |
| Skip 4-yard (for hacked-off render) | £190 |
| Cement (5 × 25kg) | £40 |
| Plastering sand (10 × 25kg) | £55 |
| Lime + plasticiser | £35 |
| SBR slurry 5L | £24 |
| Bell-cast + stop bead (replacement at openings) | £40 |
| Fibreglass mesh | £35 |
| Masonry paint 10L Weathershield + brushes | £85 |
| Labour: plasterer 2.5 days @ £340/day | £850 |
| Labour: painter 1 day @ £260/day | £260 |
| Travel & overheads (3 visits) | £120 |
| Subtotal | £1,994 |
| Markup at 22% | £439 |
| Total to customer | £2,430 |
Round to £2,400. Compare against a "we'll bodge it from a ladder" cowboy quote at £600 — that's the same job done wrong, no scaffold, no full painting, blown again within 24 months. The customer chooses.
Frequently Asked Questions
Can I patch render on a pre-1919 solid-wall house with sand-cement?
No. The original render will be lime-based and vapour-permeable. Sand-cement patches trap damp behind the patch, push moisture into the brick, and cause spalling. Use NHL 3.5 hydraulic lime or putty lime to match the original. Conservation areas and listed buildings require lime specifically.
Why does new render keep cracking around the windows?
Most common cause: no mesh reinforcement at the corners of openings. BS EN 13914-1 requires fibreglass mesh diagonals at all openings to prevent stress-cracking. Second cause: insufficient movement joints — every 5–6m horizontally and at building junctions. Third cause: render applied directly over the lintel without bridging detail.
Do I need planning permission to re-render a house?
In a conservation area, listed building, or under an Article 4 Direction — yes. In a national park or AONB you may need it. Otherwise, like-for-like re-render is permitted development. Changing colour dramatically (e.g. white to dark grey) in a conservation area can require consent. Always check with the local Planning Department before quoting.
How long should sand-cement render last?
Properly applied 3-coat sand-cement render lasts 30–60 years. Failure within 10 years is almost always poor original workmanship (wrong mix, no scratch coat, applied to frozen wall, applied too thick) or unaddressed damp ingress (failed flashings/copings above). A repair done well to the same standard lasts the same.
What's the difference between monocouche and traditional render?
Monocouche is a one or two-coat through-coloured render — the colour is in the topcoat so no painting needed for 15–25 years. Traditional sand-cement render is uncoloured and must be painted with masonry paint every 5–10 years. Monocouche material cost is 2–3× higher, but labour is faster (one application visit, not three) and lifetime cost is lower.
Regulations & Standards
BS EN 13914-1:2016 — Design, preparation and application of external rendering — Part 1: External rendering
BS EN 13914-2:2016 — Design, preparation and application of external and internal rendering — Part 2: Internal plastering
BS 5262 — Code of practice for external renderings (withdrawn but referenced in older specs)
BS EN 998-1 — Specification for mortar — rendering and plastering mortar
PD 6697:2019 — Recommendations for the design of masonry structures (movement joints, substrate compatibility)
NHBC Standards Chapter 6.11 — External render for new dwellings (mandatory on NHBC sites)
Building Regulations Part C — Site preparation and resistance to moisture
Building Regulations Part L — Conservation of fuel and power (where render forms part of EWI system)
Work at Height Regulations 2005 — Scaffold/tower required above 2m working height
Construction (Design and Management) Regulations 2015 (CDM) — Applies where work over 30 days or 500 person-days
Approved Document C: Site preparation and resistance to contaminants and moisture — gov.uk
HSE Work at Height Regulations 2005 — hse.gov.uk
SPAB Briefing: Lime Render — Society for the Protection of Ancient Buildings
external render pricing guide — full elevation re-rendering pricing
render removal pricing guide — pricing render strip-off and removal
plasterboard fixing and dot and dab — internal plasterboard companion guide
render insulation systems — EWI (external wall insulation) systems context
repointing vs tuckpointing — repointing as alternative to render repair on old brick