I had a two-storey studio built on what was the garage of our house a number of years ago.
Some time later the roof began to leak. As I was unable to contact the original builder I had to call in a roofer. While he tried to repair the leak, he mentioned that he felt that the materials used by the builder might have caused the problem. Needless to say, the repair work failed to address the issue.
I tried to contact the original builder again but was unable to reach him. So I called in another roofer and he repaired the leak for me. The repair lasted for about two years before the leak returned.
Having paid for two repairs, I made one last attempt to contact the original builder to see if he could resolve the issue. On this occasion, I was in luck and the builder came around and fixed the roof. Everything looked great until the leak returned just two weeks later. The water seems to be coming from the section where the pitched roof meets the top of the walls.
To say I am disappointed with this builder is an understatement. I have spent about €5,000 to date on roofers trying to solve the problem.
The questions I would like answered are:
I would be grateful for any advice you can give me.
With a roofing job, the materials are rarely an issue once installed correctly – they come with warranties and guarantees. The issue with a roof is almost always with the workmanship or detailing. You say the dampness is concentrated where the roof meets the walls, so I’ll focus on that.
You don’t say what type of covering was used but I note it is a pitched roof, so it is likely you used slate or tiles with lead or zinc flashings. If so, these should last 50 to 80 years with routine maintenance.
If your roof is of standard felt it would have a lifespan of 15 to 20 years, depending on the material; the high-performance roofing felts last a little longer. Either way, you are well inside these time periods.
The most likely source of a leak on a new, pitched roof is windblown rain penetrating due to an insufficient roof pitch. The rain gets in between the tiles, flows down the felt underlining and may appear along the wall in the room below.
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As a general rule, slates require a minimum pitch of around 22.5 degrees, while concrete interlocking tiles require a minimum pitch of 17.5 degrees. If low pitch is the problem, the remedy is to strip off the roof, install double underlay felt for added protection, and nail every tile when refixing, rather than every third row, as is common practice with tiles.
Again, it’s not clear what you mean by “where the pitched roof meets the top of the walls”. If the roof meets a parapet wall (a wall that extends upwards over roof level) with a valley gutter, this is a weak point on any roof and good detailing of the valley lining and flashings is critical.
Any good roofer will know the problem here and you may have to reform the valley to ensure correct construction detailing, adequate falls towards the outlets, upstands and flashings to ensure the water can escape during a heavy downpour.
Given the level of failures, I’m inclined to think there is another source of water ingress. This is a case for a building surveyor with an eagle eye and an understanding of potential roof detailing issues. Have the surveyor check for adjoining roof connections, rainwater outlets, water storage tanks within the attic, water passing laterally through an outer gable wall, etc.
On the question of warranties, most roofing materials have a manufacturer’s warranty and agrément certificate, which covers defects in the material itself. Twenty years is not uncommon and often a lifetime guarantee is available with the more well-known brands. However, poor installation can void a warranty for the product if it is not installed in accordance with the manufacturer’s guidance.
Unfortunately, after eight or nine years, you are unlikely to have much comeback with the builder and are likely to have to pay for the remedial work yourself. Even the best builder will only give a guarantee of five to 10 years on workmanship (not materials). Hindsight is always great, but for repairs, employ a professional (building surveyor, architect, or engineer) to supervise the work and obtain the relevant written guarantee from both the contractor and product manufacturer.
Keep records of batch numbers and invoices. Most roofers will not want to enter into a formal contract for such a small job but consider and encourage the use of the RIAI Short Form of Contract (SF88), which is ideal for this work.
Pat McGovern is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland
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