Repair Costs of Render and Interior Finishes After Window Replacement

Replacing wooden sash windows can leave damage to surrounding finishes, requiring extra repairs.

Below we outline typical costs for fixing exterior render and interior plaster/decoration after window installation.

If you want to avoid the additional costs of repairing render and interiors after installing new windows, consider double glazing your existing wooden windows with us. We reuse your existing sashes and refurbish them along with the box frame or casement, preventing any damage to the render and making retrofitting more affordable compared to a full window replacement.

Average Cost of Exterior Render Repair After Window Replacement

Small Patch Up: Depending on the situation, say a few fine fissures on the render or a patch near a newly installed window, fixing them through professional hands would cost in the range of £150 – £320 for a relatively small area.

This usually coincided with filling and blending the plaster to patch up the wall. Or else you could go the cheaper path on DIY and use ready-mix render.

Larger or Complicated Patches: There are different ways of quoting render repair prices – per square meter. Basics for sand-cement render repair cost $15/m², while modern examples of acrylic or polymer render repair go to $25 – $30/m².

For example, repairing an area of about 5 m² of rendering could be some £100 with standard cement but for £300 when you choose polymer or acrylic render instead. Sometimes, finishing processes like pebbledash are at the higher range (e.g. around £300 for 5 m²). Lime render (pretty common for period properties) would be costlier – around £200 for a 5 m² lime batch compared to £100 for cement.

Where damage is high up (like damage over the upper-floor windows), it can be essential to factor in the cost for access machinery.

The repair of small patches can generally be done from a ladder, but extensive render repairs over windows on the second floor may necessitate scaffolding, wherein the cost can run into hundreds of pounds (Around £1,000 per week of scaffolding for the whole project; however, one small patch job may not justify full scaffolding).

In many instances, window installers will use sealant or expanding foam and leave the outside with an untidy finish, and therefore, a renderer would be needed to rectify and finish it properly.

Cost of Interior Plaster and Decoration Repairs After Window Replacement

Installing the window itself can sometimes jeopardise plaster around the window recess (the “reveal”) due to cracking or dislocation. A plasterer will charge between £70 and £130 for a small patch of plaster repair (e.g. filling in a few cracks or a small chunk). As a courtesy, window fitters might fill minor aesthetic blemishes on the plaster if the need arises (or cover them with beading).

However, large areas of cracked or broken render may need to be replastered. Prices for patch plastering may range between £70 and up to £500 depending on the extent of damage. For instance, a “foot-sized” damaged plasterboard area would cost around £120, whereas replastering an entire wall or several reveals could cost several hundred pounds more.

Skimming and Finishing: Should the window surrounds be damaged (sides and the reveal on the top/bottom), then those areas may need to be re-skimmed by a plasterer. On average, an experienced plasterer typically charges £35-£40 per hour, and this work might take one full working day, costing roughly £300. Skimming a small wall would generally cost between £100 and £200 as a rough estimation, given its straightforward nature.

Finishing (Painting/Wallpaper): Decoration in the affected area with paint will likely be required after any plaster repair. This is particularly necessary if you decide to have the area surrounding the window painted or, in more extensive cases, the entire wall. Many homeowners undertake minor repairs themselves; if a professional decorator is hired, factor in the cost for at least half a working day.

Statistics suggest that painting a small room would cost around £350, so minor wall touch-ups may be less (approximately £100-£200) if only window-adjacent sections need attention.

For walls with wallpaper that was stripped during installation, additional wallpapering costs must be considered. Budget an extra £50-£150 (excluding VAT and labour) for DIY materials (plaster, filler, paint), or more if you’re hiring tradespeople for the finishing.

📌 Note: Reputable window companies endeavour to minimise interior damage. They often use trim or cover strips to hide small gaps instead of requiring full plaster repairs. However, if your existing plaster was in a weak condition or if the installers needed to cut sections to remove old fixing straps, more extensive repairs might be necessary.

Average Cost per Window and an Alternative to Avoid This Additional Expense

In summary, budget £150–£300 for exterior render touch-ups and anywhere from £100 up to a few hundred for interior plaster and redecorating per window, on average, after a replacement.

Costs will be on the lower end for newer homes with minimal damage and higher for older properties or extensive repairs. Always check if your window installer’s quote includes “making good” internally and externally – some include basic patching or trim, others leave it to you​

If you want to avoid repairing render and interiors after replacing windows, don’t replace them! We can double glaze your existing sashes without causing any damage to the render or interior surfaces.