Plain clay tiles used on low pitch roof. Advice needed

[Stup15]

Our builder is currently undertaking extension and reconfiguration works. They have recently finished the extension (garage) roof. This has since been inspected (and signed off) by the Local Authority building inspector (although I suspect he didn’t look closely).

The design (and as-built) of the roof pitch is 22 degrees. The builder procured plain clay tiles (Sandtoft) and installed these. I have since been informed that the minimum pitch for these should be 35 degrees.

I have since raised this with the builder who has told me it has been passed by building control (and we shouldn’t tell them the reality), and it will be absolutely fine and he will guarantee the work. Clearly this is not acceptable and I will be informing building control and looking for an acceptable solution. Does anyone have any advice on possible remedial measures (given what has been installed), rather than completely re-roofing? Any help would be welcome.

 

[datarebal]

It's done.
You are correct generally plain tiles min pitch is 35, some are 40.
Flashing is short and soaker missing

 

[mrrusty]

I'll leave it to @datarebal to pick up the quality of the install, but I'm not sure how bothered I would be about the pitch. The manufacturers have to set a limit which they are confident will perform in all situations, no matter how exposed to wind and driving rain, so they build in contingency. I suspect in that quite sheltered situation it'll be fine, particularly as BC have passed it and the builder guarantees it.

I've got slates on a single storey extension at 17 degrees (original building from 1902). The lap is way under what is now recommended, but it's fine.

 

[^woody^]

It may well be fine, and it may well work ...... right up to the point that it leaks at some random unknown future date .

The thing is, it's a risk.

Done to the correct pitch for the tiles and there is no risk and an automatic guarantee that it won't leak ...... which I would have much more confidence in than the 'builders' verbal guarantee for the very roof that he has knowingly built incorrecty !

 

[catlad]

The builder has built up to the window which is as high as he could feasibly go.
As its a single story and the rafter length is short I wouldn't worry too much as long as the workmanship is good.