Flat Roof Leaking? Emergency Repair

Because heavy rain is when water sits on the roof long enough, or deep enough, to find the weak spot.

• Ponding. A roof that has sagged holds water in a dip. Once the puddle is deeper than a joint or a crack, it gets in.
• A blocked outlet or gutter. Leaves and moss stop the water getting off, the level rises, and it runs over the upstand at the wall.
• The wall flashing. Where the flat roof meets the house, the flashing or the upstand cracks. Rain driven against the wall runs down behind it.
• Lifted edges and trims. Wind gets under the drip edge at the front and lifts the felt or rubber, and rain is blown in under it.
• Splits and blisters. Old felt cracks along the joints and blisters in the sun. A blister that has burst is a hole.

Water travels under the covering and along the deck before it drips, so the stain on the kitchen ceiling is often a metre or more from the fault.

• Bucket under the drip, and switch off lights or sockets near the wet at the fuse board.
• If you can see the roof safely from an upstairs window, look for a puddle, a blocked outlet or a lifted edge, and take a photo.
• If the outlet is blocked and you can reach it from a ladder with someone holding it, clearing it can stop the leak for the night. Don't walk on the roof.
• A weighted tarp over a low flat roof can do for a night if it's safe to reach. Keep it clear of the outlet.

Then send the form and pick "Flat roof or felt". The roofer will ask where the damp shows and what's above it.

One split, one blister or one lifted edge on a roof that is otherwise sound is a repair. Leaks in several places, felt that cracks when it's pressed, or a deck that feels soft underfoot mean the covering has had its day, and patching only moves the leak.

Torch-on felt lasts about 10 to 25 years, so a felt roof on an extension from the 1990s or 2000s is often at that point now. A rotten deck is replaced at €30 to €50 a m² extra. For the full costs of a new covering, see flatroofreplacement.ie.