Maintenance, Repair and Waterproofing
Maintenance, Repair and Waterproofing tests defect diagnosis, repair methods and moisture control. Expect cracks, efflorescence, damp patches, spalling concrete, honeycombing, leaking roofs, wet areas and failed joints.
Core rules
- Diagnose the cause before repairing: settlement, thermal movement, poor drainage, salt attack, reinforcement corrosion or failed waterproofing.
- Rake out and clean cracks, then use a compatible filler or grout; structural cracks need engineer-approved stitching or strengthening.
- Remove loose plaster and concrete before re-plastering or repairing; prime the surface as specified.
- Roof waterproofing needs correct slope to drains, a continuous membrane or coating, and protected details at parapets and outlets.
- Wet areas need a waterproofing system turned up at walls and tested by ponding before tiling.
Worked example
A 100 m2 roof receives two coats of a waterproof coating at 1.5 kg/m2 per coat. Total coating = 100 × 2 × 1.5 = 300 kg. If the roof falls 1:100 over a 5 m run, the fall is 5,000 ÷ 100 = 50 mm. Check that the average thickness and the outlet detail meet the manufacturer’s requirement; a coating cannot compensate for a backfall.
Traps that cost marks
Painting over damp, filling a live crack without finding the cause, and skipping the ponding test are common. Do not apply a rigid repair to a movement joint; it will crack again.
Key points
- Diagnose the cause before choosing a repair method.