Leaking roof with velux windows

5 Feb 2021
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United Kingdom
I am seeking advice on replacing the leaking roof on 4 year old extension which has been an issue for some time. The roof is pitched at approximately 15°. There are 3 Velux windows which are pitched just below 15°, the app used showed between 14.3°-14.7°.

The plain Redland tiles currently on the roof are suitable only for a 35° pitch and we intend to replace them with Redland Regent interlocking tiles which are approved for 12.5° pitch. In the process new battens and a quality breathable felt underlay (e.g. Permo Forte BBA approved), new flashings by the main wall at top of the roof and dry verge caps will be used.
A few roofers advised that new tiles and the above mentioned adaptations should resolve the issue. However, it has also been suggested by one of the professionals that the pitch on the roof and veluxes should be raised as the veluxes are fitted slightly below the manufacturers recommended minimum of 15°. We would rather not have the veluxes removed to raise the pitch in case of any damages that this may cause inside the extension ceiling. There may also be additional costs for replacement of flashing surround kits.
The dilemma we are faced with is whether to replace just the tiles which hopefully should stop any future water ingress or should we also have the roof/veluxes pitch raised for our piece of mind.
The Velux area with the leak is close to the outside edge of the roof and seems to be more effected by rain especially when the wind is blowing into the direction of the roof. There are no leaks around the other two veluxes which makes me think that the problem is more to do with rain water slipping under the tiles rather than the veluxes pitch being slightly under 15 degrees. Can anybody advise on the matter?
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There are literally hundreds of threads where Velux's leak on roofs beneath 15°, do a search. Ask yourself if you could actually just do away with them when you replace the tiles? You'll either need an ugly upstand or to hope for the best. Nobody can predict if your rooflight leaking is down to the pitch of the rooflight being too little, poor workmanship from the off or the incorrect tiles as currently fitted. Re-post in Roofing and add some pics of the roolfights flashings.
Try with the regents. If there's a leak round the velux then alter them after. No big deal

Plain tiles leaking at 15... Yes they will. Lead flashing is going to need adapting or changing .. it's no use even with the plain tiles
I read quite a few posts on this forum in relation to our roof / velux issue but thought l would ask anyway for some opinions on our specific case. This is what these forums are for.

We need to get a roofer to replace the tails as we are adamant that the tails used are the wrong type which are the reason for our roof not being water tight. I wanted to hear from people who had been in exactly same situation or professionals who dealt with it, to get their opinions whether the best course of action would be to replace the tails and hope that the correct tiles and good quality membrane will be enough. This is what we were advised by a couple of roofers. We were also told by another roofer that he could raise the pitch to remedy the possible issue with veluxes. Only one of the veluxes showing water stains so we were wondering if it was an issue with velux pitch being less than 15 degrees therefore,
wouldn’t all 3 veluxes be effected? Hence, our dilemma and not knowing which of the roofers can we trust as to what needs to be done. They are all keen to take our money and offering 10, 15 and even 25 years guarantee but what is the guarantee worth. The builder who build our extension offered 10 years guarantee but 4 years later he is not interested in putting things right. Thank you for your response. I have posted my query including pictures on Roofing forum so hopefully l will get some suggestions.
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Thank you for recommending the tiles. We have already purchased Redland Regent after doing our research.
The roofer who inspected the roof also told us that lead flashing has to be changed and possibly we may need new flashing kits for the veluxes. He would be able to confirm this once he takes a closer look.
I suspect everything will be ok once the tiles are changed and you have someone who knows what they are doing fitting them. Choose the one who mentions fitting BFX collars with the new flashing kits!
Hope you are right. We have picked the roofer who specified in detail the materials he wants to use which are top grade. He is not the cheapest but hopefully he is worth it.
Thank you for the tip on BFX collars.

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