How to deal with cracked or damaged walls

How to deal with cracked or damaged walls

Wouldn't it be nice to start every job from scratch? Unfortunately, professional decorators know that this is not always the case, and that inheriting mistreated and damaged walls is all part and parcel of the job. Dealing with damage can be a complex task, so we've rounded up the most common types of problem, and the solutions for each:

Cracked caulk

Problems with cracking caulk usually arise from one of the following:

  • Low quality caulk. Make sure you’re using a good quality permanent acrylic sealant.

  • Caulk over-applied. Caulk is only intended to fill gaps of 2-3 mm, so trying to use it as a filler for areas larger than this can lead to cracking.

  • Application of paint before caulk is fully dry. Ensure that caulk is dry throughout (not just surface dry) before painting over.

If caulk has cracked, the only real solution is to rake the cracked caulk and re-apply in the correct manner. There really is no shortcut!


Damp can cause a number of problems, but the most important thing to do is identify the source of the damp and rectify it, or the problem will return. It may be a broken DPC, leaking gutter or just poor ventilation, but the potential problems include adhesion failure, blistering, flaking, promotion of moulds and staining. To deal with damp areas, you must do the following:

  • Remove unsound coatings

  • Treat mould (see below)

  • Allow surfaces to thoroughly dry and test with moisture meter if in doubt.

  • Block staining as required with Dulux Trade Stain Block Primer.

  • Ensure surfaces are dry when redecorating  


Mould flourishes in conditions of high humidity, poor ventilation and on surfaces with a high moisture content. It can be very destructive to paint finishes and needs to be eradicated before applying paint. Treat affected areas with Weathershield Multi-Surface Fungicidal Wash. Leave on the surface for 24 hours, scrub with a stiff brush (not metallic) or nylon abrasive pad, and wash down to remove residues. Allow to dry thoroughly. If necessary, repeat the treatment. Use two coats of Dulux Trade Mouldshield Fungicidal Eggshell to help reduce the likelihood of mould returning.


Blistering is almost always caused by moisture and/or heat on or in the surface, which has been painted without being allowed to dry properly. The moisture tries to evaporate but cannot escape through the paint. Once blistered the paint will eventually crack and peel allowing more moisture in. To resolve the problem, scrape back the blistered paint until you have a firm edge, feather lightly with abrasive paper and dust off. Now spot-prime and bring forward any bare areas with a Primer Sealer, using Dulux Trade Stain Block+ on friable surfaces. Finally, repaint the surface using a thinned first coat of water-based Dulux Trade Diamond Eggshell onto the primed area followed by one or two full coats, ensuring the surface is dry and free of dust before re-applying coatings.

Cracks in plaster

It's quite normal for small cracks to appear in plaster on interior walls and ceilings, either through drying out in new homes or movement of the building in older homes. Simply enlarge the cracks slightly using a scraper (fillers don't work well in hairline cracks), dust off and fill with a suitable product such as Polycell Trade Interior filler. Dampen the hole or crack with water - this will help the filler to bond. Allow the filler to dry fully, then rub down smooth and dust off to create a clean, smooth surface for decorating. To ensure even porosity spot prime with a thinned coat of your finish before painting the affected area (only if the finish is matt).

Crazed paint

Possible causes of crazed paint include:

  • Application of Matt onto silk

  • Too thick a film

  • Quick change in temperature while drying

How to correct it depends on which of the above caused it, but as a general rule of thumb, you should rub down the affected areas and apply two thin coats of paint with a roller. If the crazing has been caused by application of matt onto silk paint, apply a coat of Dulux Trade Vinyl Soft Sheen. Where the crazing is really severe, it may be necessary to fully strip the wall down, apply lining paper and re-paint.

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