How Much Does It Cost to Repair a Flat Roof?
£300 – £2,500
per job
Flat roof repairs cost between £300 and £2,500 depending on the size of the affected area, the type of flat roofing material, and whether the deck itself has been damaged by water ingress. Small patch repairs to a felt or EPDM roof are at the lower end; repairing a large blistered felt roof or fixing structural deck damage costs considerably more.
Average cost
£300 – £2,500
per job
Prices vary by region, property type and tradesperson. Always get at least two quotes.
What affects the price?
Extent of damage - a small split or blister in the membrane costs £300-£600 to patch; widespread failure requires stripping and relaying at £50-£120 per m2
Flat roof material - felt, EPDM rubber, fibreglass (GRP), and liquid waterproofing systems all have different repair methods and material costs
Deck condition - if water has penetrated to the plywood or OSB deck, the damaged boards must be replaced before a new membrane is applied
Access - ground-floor extensions and garage roofs are easy to access; higher roofs add to labour time
Labour vs materials
Labour accounts for 50-60% of the cost of a flat roof repair. A roofer day rate runs £150-£250; materials for a membrane patch or small section relaying add £50-£200.
Repair or replace?
If a flat roof is over 15-20 years old and has multiple areas of failure, a full replacement is usually more cost-effective than continued patching. A new fibreglass (GRP) or EPDM flat roof on a standard extension costs £1,500-£4,000 and carries a 20-25 year guarantee.
Questions to ask your tradesperson
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