Crack repair

Addressing a crack early is almost always more cost-effective than waiting. A professional bricklayer or structural specialist can determine if a crack is "live" (still moving) or "dormant," ensuring the repair is a permanent solution rather than a temporary mask.

What Does the Work Involve?

• Initial Assessment: Measuring the width, direction (vertical, horizontal, or stepped), and location of the crack to identify the likely cause.
• Surface Preparation: Raking out old mortar and removing loose debris from the crack to ensure a clean bonding surface.
• Crack Stitching: For structural cracks, stainless steel "helical bars" are inserted into grooves cut across the crack and bonded with high-strength resin.
• Resin Injection: Injecting specialised epoxy or polyurethane resins into deeper fissures to seal the void and prevent water ingress.
• Repointing: Carefully matching the new mortar to the existing colour and texture to ensure the repair is visually seamless.
• Monitoring: In some cases, installing "tell-tale" gauges to monitor movement over several months before committing to a permanent repair.

Typical Costs

The cost of crack repair varies significantly based on whether the issue is cosmetic or structural. Prices below include labour, materials, and VAT at 20%.

Factors affecting the final price include the height of the repair, the type of brick used (older reclaimed bricks are more expensive), and whether the property is built with lime or cement-based mortar.

How Long Does It Take?

• Minor Cosmetic Repairs: 2–4 hours for simple raking out and repointing.
• Standard Crack Stitching: 1–2 days for a typical 3-metre crack, including curing time for the resin.
• Major Structural Reinforcement: 3–5 days if multiple elevations require helical bar installation and extensive repointing.
• Drying Times: Mortar and resin typically require 24–48 hours to fully cure before any external painting or finishing can occur.

DIY or Professional?

Filling a hairline crack in a garden wall is a manageable DIY task, but cracks in the main dwelling should almost always be assessed by a professional. Structural repairs often fall under Building Regulations (Part A), and incorrect DIY fixes can mask serious issues, leading to mortgage or insurance complications later.

Note: If a crack is wider than 5mm or you can see daylight through it, do not attempt a DIY fix. Consult a structural engineer or a specialist bricklayer immediately.

Choosing the Right Tradesperson

• Check Qualifications: Look for bricklayers with NVQ Level 2/3 or specialists registered with the Federation of Master Builders (FMB).
• Specific Experience: Ask if they have experience with "helical bar installation" or "crack stitching" rather than just general bricklaying.
• Red Flags: Be wary of anyone who offers to "just fill it with mortar" without investigating why the crack appeared in the first place.
• Questions to Ask:
  • Do you provide a guarantee for the repair work?
  • Will the new mortar be colour-matched to my existing walls?
  • Do I need a structural engineer’s report before you start?
  • How will you handle dust and debris during the raking-out process?

UK Regulations

• Building Regulations (Part A): Major structural repairs must comply with standards for structural integrity.
• Party Wall Act: If the crack is on a shared wall with a neighbour, you must legally notify them before commencing work.
• Listed Buildings: If your home is listed, you will need Listed Building Consent before using modern resins or cement-based mortars.
• Paperwork: Keep all invoices and engineer reports; these are vital when selling your home to prove the building is structurally sound.

Common Problems

• Using the Wrong Mortar: Using modern cement on an older lime-mortar property can trap moisture and cause bricks to "spall" (flake away).
• Ignoring the Root Cause: Repairing a crack caused by a leaking drain or a tree root without fixing the source will result in the crack reappearing within months.
• Poor Colour Matching: Using standard grey mortar on weathered or red-toned brickwork can leave a permanent, unsightly scar on your home's exterior.
• Insufficient Stitching: Installing helical bars that are too short or spaced too far apart will fail to bridge the structural load effectively.

Frequently Asked Questions

Is every crack in my brickwork a sign of subsidence?

No. Many cracks are caused by "thermal movement" (bricks expanding in summer and contracting in winter) or simple settlement in newer homes. Subsidence cracks are typically diagonal, wider at the top, and often appear near door or window frames.

Will my home insurance cover the cost of crack repairs?

Insurance usually covers repairs if the cause is subsidence, heave, or landslip. They rarely cover "wear and tear" or cracks caused by thermal movement or poor original construction. Check your policy for the "subsidence excess," which is often £1,000.

What is "crack stitching" and is it permanent?

Crack stitching involves embedding stainless steel rods into the mortar beds across a crack. When done correctly with high-quality resin, it is considered a permanent structural repair that is stronger than the original masonry.

Can I just use silicone sealant to fill an external crack?

Never use silicone for brickwork cracks. It traps moisture behind the sealant, which can lead to damp inside the home and frost damage to the bricks in winter. Always use a breathable, mortar-based filler.

How do I know if a crack is "active"?

A professional can install a "tell-tale" glass or plastic gauge over the crack. By checking the gauge over 3–6 months, you can see if the crack is widening, narrowing, or shearing, which dictates the type of repair needed.