A flat roof on a kitchen, porch or garage extension is the part of a house that most often leaks, and the one where repair-versus-replace is hardest to guess from the ground. Water often turns up well away from its entry point, because it runs along the deck before it drips through a ceiling, so the stain on the ceiling rarely marks the fault itself.
Q2.1When is a flat-roof repair enough?
A local failure at an edge trim, a split along an upstand or a blistered patch can be cut out and renewed, with the new section lapped into the old so water is shed, not trapped. If the deck below is dry, the repair can last for years. The flat-roofing materials we work with have typical lifespans of around 20 to 30 years for EPDM, with other coverings spanning a similar range, though workmanship and maintenance move those figures either way.
Q2.2When is it time to replace?
If leaks have appeared in more than one place, the surface is crazed or lifting, or the deck beneath has gone soft and dark, a new covering is the sensible job. The fall also matters: a finished roof should drain, with a design fall of 1 in 40 so that a finished minimum of 1 in 80 is achieved, and ponding is a reason to look at the deck. See our flat roofing page for the options. We take the old covering away with the rest of the waste, and the new one carries our written 10-year workmanship guarantee.
Q2.3How much might the new covering cost?
MyBuilder's national flat roof guide, updated 21 August 2026, gives bitumen felt at £70 to £100 per m² and EPDM at £90 to £130 per m². Access, deck repairs and size move that, so our written quote follows the survey.