How to fix cracked paint on walls

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

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

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

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.

Need more help with damaged walls? Search our Q&As.

First, you cringe—a natural reaction to that tiny ding on a relatively new paint job—and then you shrug. Some paint imperfections, however, are more conspicuous and harder to overlook. Such issues must be addressed, the sooner the better, not only to restore the painted surface but to investigate potential underlying problems.

Read on to understand the causes of common paint problems and how to repair them and avoid future issues.

Cracking, Flaking, and Clumping

Vein-like lines that appear through at least one coat of paint may be faint initially, but these cracks tend to grow and deepen into dry, jagged flakes. Such unsightliness can strike a variety of surfaces, indoors and out, from plaster to wood and siding.

What causes paint to crack?

Insufficient surface prep is the main culprit behind crack attacks. Over-thinning your paint or applying it too thinly can also cause it to split.

Conversely, a heavy hand while painting can lead to what’s called mud cracks, where too-thick paint dries with a clumpy, swollen look. Not allowing adequate dry time between coats can also lead to these problems. And unfortunately, cracks can appear simply due to age. Over time, paint becomes brittle, making it less adaptable to temperature and humidity fluctuations.

Repair and Prevention

If damage is extensive, you may need to repaint the entire surface. If not, with the right technique, you can repair a poorly painted spot without a lot of headache. Follow the tips detailed below for solutions.

1. Remove all cracked and flaking paint with a scraper, wire brush, heat gun, or chemical application (depending on the extent and severity of the problem).
2. Sand, feathering the edges to blend, then clean and prime the surface.
3. Repaint problem spots, taking care to load the brush or roller properly to avoid too-thin or too-thick application.
4. For brush application, dip the brush in, allowing paint to cover up to one-third of the bristle length; tap the brush lightly on both sides and avoid dragging the brush against the edge of the container.
5. If using a roller, fill the roller tray halfway. Remove lint from a new roller cover, dip the roller into the well of the tray, then over the ribbed portion of the tray, repeating several times to evenly distribute the right amount of paint.

To avoid heavy buildup in corners where paint commonly overlaps, thoroughly feather out the cut-in area; then clean and prep, reapplying paint evenly. And be patient, always remembering to let paint dry fully between coats. When repainting to repair, you’ll likely want to apply the same product you used initially (but in subsequent projects, opt for quality latex paint, known for its adhesion and flexibility).

Peeling

Peeling paint that has a bit of curl to it is a common problem on both interior and exterior surfaces.

What causes paint to peel?

While improper prep and application can contribute to peeling, moisture is public enemy number one.

1. Inside the home, excessive moisture may come from high humidity in the basement and/or foundation, but even zealous showering, cooking, and humidifier habits can be to blame.
2. Outside the house, peeling can result from inadequate caulking, clogged gutters, a leaky roof, or interior moisture that seeps through exterior walls. Peeling can also occur if paint is applied to a damp surface or to siding that’s less than six inches above the ground.

Repair and Prevention

Watch: Repairing Peeling Paint

Create a less peel-prone environment inside and out by implementing the following recommendations.

Improve interior ventilation as needed with exhaust fans, wall vents, and/or louvers.

For exterior conditions such as crumbly caulking, full gutters, or loose shingles, remove peeling paint by sanding, cleaning, and priming before repainting.

Blistering a.k.a. Bubbling

Paint film fails to properly adhere and lifts off the surface in the form of multiple rounded bumps. Blisters can appear on both interior and exterior painted surfaces—drywall, plaster, metal, and wood.

What causes paint to blister or bubble?

Heat and moisture are both blister gremlins. Painting in direct, intense sunlight or on overly hot surfaces can cause heat bubbles on exteriors; newly dried latex paint that’s exposed to dew, rain, or high humidity may also blister.

On interiors, moisture passing through the walls from bathrooms, kitchens, basements, and laundry rooms can push paint off the surface. Oil-based paint is also apt to blister when applied over a damp surface—or when applied over water-based (latex) paint. Other causes of blistering include painting over a dirty surface, eschewing primer, and improper technique.

Repair and Prevention

Burst a few bubbles and examine the backside of blistered paint, as well as the substrate if it becomes exposed, to determine if moisture or heat is the culprit.

1. If the blisters contain several coats of paint and popping them reveals bare substrate, there’s a moisture issue. Address this by repairing plumbing, replacing caulking, and/or increasing ventilation as required. Then remove all blistered paint, sand smooth, clean, prime, and repaint.
2. If blisters affect only the previous coat of paint, heat is likely at fault. Remove blisters and the underlying paint or primer, then sand to smooth and dull the surface, clean, prime, and repaint, taking care that the surface is below 90º F.
3. Stir paint slowly yet briefly with a wooden stirrer or drill attachment. Stirring too quickly or for too long can introduce bubbles to the paint that could transfer to the surface.
4. Be patient when rolling. If you detect bubbles during application, slow your stroke speed.
5. Ideally, stick to one formula to avoid blistering: latex over latex and oil over oil. While it’s possible to successfully apply latex paint over oil-based primers and paints if necessary, you should try to avoid doing so as it’s likely to lead to blistering.

Efflorescence

Crusty white salt crystals may look appealing on a pretzel, but not on the painted masonry of your home. Efflorescence (also known as mottling) appears when the salts inherent in brick, concrete, cinderblock, and mortar dissolve in moisture and then leach out to the surface.

What causes efflorescence?

A variety of factors contribute to efflorescence, including:

• insufficient curing time for cement or mortar during construction;
• moisture migration from inside the house;
• groundwater penetration from an inadequately waterproofed basement;
• insufficient surface prep to remove previous efflorescence; and
• painting over holes, cracks, or unrepaired pointing.

Repair and Prevention

Tackle efflorescence on a warm, dry day. Eliminate excess moisture conditions externally by waterproofing and repairing cracks, repointing, and sealing around windows and doors with butyl rubber caulk.

There are various ways to remove efflorescence, and you may need to use a combination, depending on the extent and severity: a wire brush, scraper, low-pressure washer, and/or cleaning with diluted white vinegar or a trisodium phosphate (TSP) solution (wear protective gear when working with this chemical) and then rinsing thoroughly.

Applying an impregnating hydrophobic sealant to a building material surface can prevent water absorption and keep moisture from entering the material. Colorless water repellents may prevent efflorescence from recurring, as may silicone or acrylic coatings. Allow to dry completely before repainting.

Alligatoring

Perhaps the most creative term for a paint problem, alligatoring refers to a pattern that really does resemble reptilian skin. It starts as subtle wrinkling (a.k.a. checking), then develops into wide rectangular cracks. Alligatoring tends to be more common with oil-based paints.

What causes alligatoring?

Paint naturally expands and contracts in response to temperature fluctuations and, over time, loss of elasticity can result in alligatoring.

The process can be hastened through such missteps as applying a rigid coating such as oil enamel over a softer, more flexible coat (e.g., latex paint or latex primer); painting over a glossy finish (the topcoat not bonding properly to the glossy finish), or not allowing sufficient dry time between primer/basecoat and topcoat.

Repair and Prevention

1. Remove unsightly scales by scraping, sanding, applying chemical removers, or using a heat gun.
2. Then rinse to banish dust and let dry completely. Prime, allow to dry and repaint.

Chalking

A fine, powdery white substance that forms on painted exteriors, chalking is most often seen in arid, sunny climates. It tends to be most visible on pale-colored flat paints and is likely to occur on improperly sealed porous materials and poor-quality, factory-finished aluminum siding.

What causes paint to chalk?

The pigments in paint are naturally released when exposed to weather changes, so some chalking is to be expected over time. But serious cases are usually due to using the wrong product—either interior paint or low-quality exterior paint that contains a high degree of extenders (white, powdery paint additives). Over-thinning paint prior to application can also lead to chalking.

Repair and Prevention

1. Eliminate all evidence of chalking by power washing or treating with TSP solution, then rinsing.
2. Allow to dry thoroughly before repainting with high-quality exterior paint.