Cracks dealt with at the cause, not painted over.
Cracks opened out, filled and reinforced where the wall is actually moving, after we work out what caused each one, because a hairline in the putty film and a crack at a column junction aren't the same repair.
- Free site inspection
- Written, itemised quote
- 1-year workmanship warranty
- Same-day callback
At a glance
How do you repair cracks in a wall before painting?
By opening each crack out and filling it, not by skimming putty over the line. Putty bridges a crack; it doesn't hold one shut, so the bridge just tears in the same place. We cut the crack to a V, clean it out, fill with polymer-modified mortar, bed mesh across junctions, then cure, level and prime before any colour goes back on.
When this is the answer, and when it is not.
Sending you to the wrong service wastes your money and our time. This is how to tell.
This is likely right if
- Fine cracks have appeared in the paint or putty and you want them sorted before the wall is repainted
- Cracks are showing along the junction where a wall meets an RCC column, beam or ceiling slab
- A straight crack has opened along the line of a buried electrical conduit or a plumbing chase
- The same cracks have reopened in the same places since the last painting round
Something else comes first if
- The crack runs diagonally from the corner of a door or window, shows on both faces of the wall, or has one side sitting proud of the other, that needs a structural engineer's opinion before anything is filled
- The wall is damp around the crack or water comes through it in rain, the water path has to be traced and treated first, or the repair simply seals the damp inside the plaster
- The plaster sounds hollow over a wide area around the crack, that plaster has lost its bond and has to come off and be rebuilt, which is plaster repair, not crack filling
What the service includes.
Crack survey and classification
We go over each wall and sort what's there: crazing in the paint or putty film, shrinkage cracks in the plaster, straight lines following a buried chase, and cracks at the junction where blockwork meets an RCC column, beam or slab. Each of these is filled differently.
Moisture and hollow-plaster check
We tap along and around every crack. Plaster that sounds drummy has lost its grip on the wall and won't hold a filler. We also check for moisture around the crack, because filling over a wet wall traps the water behind the patch.
Dust control and protection
Cutting cracks open throws fine plaster dust that travels through a flat. Floors sheeted, furniture covered, doorways screened and the working area closed off before the grinder or blade comes out.
Cutting open and cleaning out
Each crack is cut back along its full length into a V-groove, roughly six millimetres wide and deep, so the filler has something to key into. The groove is then brushed and blown clear of loose plaster and dust.
Filling, reinforcement and levelling
Grooves damped and filled with polymer-modified cement mortar, pressed in rather than smeared across. Where a crack sits on a junction between two materials, glass-fibre or chicken mesh is bedded over it and lapped well onto both sides before the patch is brought level.
Priming and blending the repair
Patches cured, dried, puttied and sanded flush with the wall around them, then primed. A repair that goes straight under topcoat without primer flashes through as a dull stripe in the finish, particularly in side light.
Not included, or quoted separately
- Structural assessment, an engineer's report, and any structural remedial work
- Tracing a leak and treating its source, damp treatment and waterproofing are quoted separately
- Large-area re-plastering where the plaster has debonded and has to come off the wall
- Concrete repair where reinforcement is exposed or corroding in a beam, column or slab soffit
- Cracks in floors, screed, tiles or stone, this scope covers walls and ceilings
The sequence.
Inspection and crack mapping
We mark and photograph every crack, measure its running length, and note width, direction and which face of the wall it appears on. The quotation and the method are built from that, not from the room size.
Deciding what each crack needs
Some are opened and filled, some need mesh across a junction, some need the surrounding plaster off first. Where one looks live, we mark a dated line across it and ask you to leave it a season, because filling a crack that's still moving only cracks the filler.
Protect the area and cut open
Covering, sheeting and screening first, then all the grooving for a room done in one go, it is the dusty stage and there's no sense in repeating it.
Fill, reinforce and cure
Mortar pressed into the grooves, mesh bedded where two materials meet, then the patches kept damp while they cure and left to dry right through. Rushing this is exactly how a repair shrinks back and shows as a fresh hairline.
Level, sand and prime
Putty feathered out well beyond the patch so there's no ridge at the edge, sanded flat, then primer over the repair and the surrounding area.
Repaint and walk the wall with you
Finish coats taken corner to corner rather than stopped at the patch, then a walkthrough where we look along the wall at a low angle in daylight, which is where any ridge or flashing shows up.
What moves the price on this job.
We do not publish a rate, because it would change once someone measured your property. These are the variables that decide it.
- Total running length of cracking, measured along each crack rather than by the area of the wall
- What the crack turns out to be once opened, a hairline in the putty film is a different job from one running through the plaster into a block joint
- Whether the plaster around it is sound, or has to be cut back and rebuilt before filling
- Whether reinforcement is needed, mesh across a junction, or a chased channel that has to be re-plastered along its length
- Interior or exterior, and the access a crack needs, a ladder, a cradle or scaffolding on an upper floor changes the work considerably
- How much of the wall has to be repainted for the repair to disappear, which is usually corner to corner rather than the patch alone
Wall Crack Repair — your questions.
Why do the same cracks come back after every painting?
Because they were painted over rather than opened. A paint or putty film can bridge a fine crack, but it can't hold the wall still. The plaster keeps moving with heat and moisture, and the film tears along the weakest line, which is the old crack. Cutting the crack open and filling it with a material that keys into the groove is what changes that.
How do I know whether a crack is structural?
Width, direction and behaviour. Cracks that run diagonally from the corner of a door or window, appear in the same place on both faces of a wall, pass through an RCC beam or column, or leave one side standing proud of the other are treated as structural until an engineer says otherwise. We mark a dated line across a crack and re-check it after a season to see whether it is still moving.
Can you repair the crack and just touch up the paint over it?
We can fill the crack, but a touch-up over it rarely disappears. The patch takes primer and paint differently from the wall around it, so the repair reads as a change in sheen even when the colour matches, and side light makes it obvious. We normally take the finish coat corner to corner on the affected wall, and tell you at the inspection which walls that means.
Our flat is new and cracks have appeared where the wall meets the ceiling. Is that normal?
It is common. New plaster shrinks as it dries, and the concrete frame and the blockwork move by different amounts, so the joint between them opens as a fine straight line. It is usually cosmetic, and it is repaired with mesh bedded across the junction rather than with filler alone. Raise it with your builder or the association first, it may sit with them to put right rather than with you.
Should cracks on an outside wall be repaired before the monsoon?
Yes, and with dry weather to work in. An open crack on an exterior wall is a route for rainwater into the plaster, and once the wall behind is wet the filler won't bond and the damp comes through the paint. The surface has to be dry going in and the patch needs dry conditions to cure, so exterior crack work is planned around the rain rather than through it.
Related services
- Plaster RepairIf the plaster around the crack sounds hollow, it comes off before anything is filled.
- Dampness and Seepage TreatmentCracks that stay wet or return each monsoon are a water problem first.
- Wall Putty ApplicationWhat brings the repaired patches and the rest of the wall back to one level surface.
Let us look at your walls first.
Tell us about the property and we will set up a free colour and wall inspection. You get a written, itemised quotation afterwards, with no obligation to go ahead.
- We call you back the same day to get a picture of the property and the surfaces.
- We agree a time and come out for the free inspection.
- You get the written scope and itemised quotation.
- Nothing starts until you approve it.