Façade Cracking

Inspection Requirements

• Map all visible cracks on external facade surfaces, recording width, orientation, length and location relative to structural elements and openings.
• Classify cracks as hairline (<0.1 mm), fine (0.1–0.3 mm), medium (0.3–1 mm) or wide (>1 mm) using a calibrated crack gauge.
• Determine whether cracks are active or dormant by installing tell-tale gauges and taking readings over a minimum 4–6 week period.
• Assess crack pattern to assist diagnosis — vertical cracks indicate tensile forces, diagonal cracks at openings suggest settlement or differential movement, and horizontal cracks may indicate lateral loading.
• Inspect movement joint locations relative to the crack pattern — cracking at mid-panel locations often indicates absent or inadequate movement joints.
• Check the facade for signs of thermal bowing, particularly in render or masonry panels with dark coloured finishes or limited ventilation behind.
• Review structural drawings to understand load paths, slab deflection allowances and movement joint locations relative to observed cracking.
• Engage a structural engineer to assess all cracking, determine cause and confirm the repair specification.

Typical Repair Methodology

Facade crack repairs must be preceded by structural assessment. Active cracks require a monitoring period and root cause identification before repair — otherwise recurrence is certain.

1. 01.Engage a structural engineer to assess all facade cracks and determine whether they are structural, thermal, shrinkage or settlement-related before proceeding with repairs.
2. 02.Install crack monitoring gauges at all active cracks and record movement over a minimum 4–6 week period before undertaking repairs.
3. 03.Erect scaffolding or swing stage to provide safe access to all cracked areas of the facade.
4. 04.For dormant hairline to fine cracks in render, prepare by raking out to 5 mm depth, clean, and fill with a flexible paintable sealant or crack filler.
5. 05.For dormant medium to wide cracks in render or masonry, rake out to a minimum 20 mm depth, clean thoroughly and fill with a compatible flexible cementitious or polymer repair mortar.
6. 06.For cracks in structural concrete, engage an engineer to specify whether epoxy injection (for load transfer) or flexible sealant (for dormant movement cracks) is appropriate.
7. 07.Install movement joints at all locations where cracking recurs due to absent joints — cut to full depth, install backer rod and seal with a compatible polyurethane or polysulfide sealant.
8. 08.For active cracks that cannot be arrested, install a flexible backer rod and sealant repair that accommodates ongoing movement.
9. 09.Repair all damaged render, coatings and surface finishes over repaired crack locations after the repair mortar or sealant has cured.
10. 10.Apply a crack-bridging elastomeric coating over the repaired facade surface where specified to prevent surface cracking reappearance.
11. 11.Record all crack locations, repair details, product information and monitoring data for the strata and owner records.