Nine times out of ten a leak is not a hole in the roof. It is a detail that has failed. Here is how we work backwards from the drip to the cause.
Start where water gets in, not where it appears
Water travels. It can run along a rafter, follow a nail line or sit in a felt lap for metres before it finds a gap in the ceiling. The wet patch in your bedroom is very often several metres from the actual fault.
Note when the leak appears. Only in driving rain from one direction points to a wall or flashing. Only in heavy prolonged rain points to a saturation or gutter issue. Constant slow staining with no rain points to condensation rather than a leak at all.
The usual suspects, in order
Chimney flashings are the single most common cause we attend. Old cement fillets crack and let water straight down the side of the stack. Lead step flashings that have lifted or perished do the same more quietly.
After that come slipped or cracked tiles, failed ridge or hip mortar, split valley linings, perished felt at the eaves, and blocked gutters overflowing back under the tiles. Roof windows and soil vent pipe collars round out the list.
Leaks that are not roof leaks
Condensation in a poorly ventilated loft produces damp insulation, black spotting on timbers and drips that appear on cold clear nights rather than during rain. Fixing that means ventilation, not roofing work.
Penetrating damp through a saturated wall, a failed rendered parapet or a leaking overflow pipe all mimic roof leaks convincingly. A roofer who checks these before quoting is worth keeping.
What to do before help arrives
Contain and record. Put a bucket down, pierce a bulging ceiling in one controlled spot to release trapped water rather than letting it collapse, and photograph everything from inside and outside from ground level.
Do not climb up in wet or windy conditions. Almost every serious accident we hear about involves a homeowner on a ladder in weather no roofer would go up in.
Why does my roof only leak in heavy rain?
That usually points to a capacity or overflow problem such as a blocked gutter or valley, or to a detail that only fails once water is driven at volume, like a lifted flashing.
Can a roof leak with no visible damage?
Yes, and frequently. Failed underlay laps, cracked mortar and hairline splits in lead are invisible from the ground but let significant water through.
How quickly should I get a leak looked at?
Within days. Water sitting in a ceiling void soaks insulation, rots timber and reaches electrics. The repair rarely gets more expensive but the damage around it always does.
Will you find the leak on the first visit?
In most cases yes, because the failure points are well known. Occasionally we need to lift tiles in a couple of places or wait for rain to confirm the path.
Should I get the ceiling fixed first?
No. Fix the roof, let the ceiling dry fully over several weeks, then redecorate. Plastering over a damp void just hides the problem.
Evans Roofing & Maintenance Ltd, Witney, Oxfordshire. Call 07960 482233 for a free written quote.