Leaking pitched roof around velux

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 seeping under the tiles rather than the veluxes pitch being slightly under 15 degrees. Can a half degree below recommended 15 degree velux pitch be crucial or can we get away with re-tailing the roof without raising veluxes / roof pitch ? Can anybody advise on the matter?


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Id be surprised if half a degree makes that much of a difference, but I'm not a pro.

There is Others on here which know better than me and have experience of these
Seen this before.. change tiles and the lead flashing .
The pitch is ok . Tiles and lead flashing not
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How have you ended up with plain tiles on that roof?
Were they going cheap on e.bay?

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