For more than a year now, my partner and I have been trying to pinpoint the root cause of a leak on our roof and have roof works done, but in vain. The roof is still leaking.
Our roofers have confirmed and done the following:
- Coping stones are less than 10 year old (unlikely to be porous)
- Coping stones have dpc underneath them (protection from water ingress if coping stones were failing)
- Replaced the lead flashing (to correct position if lead flashing had moved/slid and caused the leak)
- Re-rendered the parapet wall (to avoid having any cracks in the render that might have caused the leak)
- Repointed the joint between the coping stones (to avoid water seeping through between the coping stones)
Need confirmation:
- dpc under the coping stones has been applied, but probably not unders the last coping stone (old sandstone keystone at the front)
- water test (buckets / watering cans) splashing onto the coping stones - no results
- water test (buckets / watering cans) splashing onto the tiles / flashing - water ingress wall, but slightly further up the party wall, NOT where the usual leak is occuring
Potential root cause > proposed solutions by our roofer:
- last coping stone failing (block keystone, sandstone) > cap the coping stones with torch / felt system
- head lap coverage of each tile / lead soaker issue > front elevation needs to be redone at the correct batten spacing to increase tile head lap
Other potential root cause:
- cracks / missing render on parapet wall (neighbours' side) allowing water to penetrate / run through the coping stones and appear on our side? > (roofer's answer: highly unlikely to cause an issue to your property unless they have the same issue in the same place)
How would you resolve this issue?
