Why is my flat roof leaking?
Assess membrane joints, edge details, outlets and upstands before blaming the whole covering.
Read guide →DampUK practical guides
Flat roofs and extensions
A flat roof relies on continuous waterproofing, adequate falls and carefully formed outlets and upstands. A stain indoors rarely identifies the precise entry point.
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Questions answered in this section
Can a small split in roofing felt cause a leak?
Location, overlap and water pooling determine whether a visible split is the entry point.
Read guide →Why does my extension roof leak against the house?
Abutment flashing and cavity tray continuity are frequent investigation points.
Read guide →Can blocked flat roof outlets cause internal flooding?
A blocked outlet can raise standing water above low upstands and door thresholds.
Read guide →Why is water coming through my rooflight?
Check kerb height, glazing drainage and membrane turn-ups.
Read guide →Does a leaking flat roof need replacing?
Local repairs may suffice when the covering is otherwise sound and compatible.
Read guide →Why is water ponding on my flat roof?
Poor falls and structural deflection may create standing water; ponding alone doesn't prove a leak.
Read guide →Can flat roof parapets cause damp inside?
Coping stones, flashings and roof edge upstands require compatible weathering.
Read guide →Why does my flat roof leak after strong winds?
Edge lifting and wind-driven rain can expose weak laps.
Read guide →Can a balcony cause leaks into the room below?
Door thresholds, waterproofing and drainage outlets form an interconnected system.
Read guide →Why is an extension ceiling wet near the wall?
The source may be at the abutment rather than directly over the stain.
Read guide →Can a green roof leak into a house?
Waterproofing integrity and drainage must be checked beneath the planted layer.
Read guide →Why is a new flat roof still leaking?
New membranes may be sound but junction details or penetrations may fail.
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