Shallow Pitch Roof Causing Leaks - Options

Hi Guys,

I've lived in my property for about 10 years and before we moved in we had a 3.5m deep, full width single storey rear extension built. The technical drawings showed that the pitch of the roof was to start just below the first floor window sill and had a pitch of approximately 20 degrees. We didn't notice that the builders actually started the roof 25-30cm below that window sill and so I check the roof pitch which is actually about 13 degrees. We've had issues once in a while, but generally the roof has been fine. Since last year we've noticed we've been getting more leaks and I've managed to fix the issue by clearing some of the moss that had built up. It looks like with the moss build up and the shallow roof pitch water is potentially being obstructed from running down properly. It tends to happen mostly where we have a down pipe from the loft coming onto the roof which causes extra water to flow down that side of the roof. We've now connected a angled downpipe from the loft downpipe along the top of the single storey sloped roof to the the bottom gutter. Not sure if that will fix the issue, but I'm guessing the real problem here is the shallow roof combined with heavier rain fall.

I'd like to ask you all what do you think my options are to rectify the situation? Do I need to change the angle of the roof (which I assume will be major work), or is there an option to do something else like using specialist roof tiles to accommodate the shallow roof?

Any help would be appreciated as I'd like to rectify the situation before winter where I think we'll end up with constant leaks.

Thanks.

Its probably always leaked and only now the felt is failing.
Look at changing the tiles to suit the pitch of your roof.

Is there any roof tiles you know of that are applicable to a 13 degree roof pitch? If it is a different type/style would there be any changes to the rafters/beams that the roof tiles sit on or are tiles interchangeable without any major change to the underlying support?

What tiles have you currently got?

Are they the standard ‘concrete’ jobs? Double pan/roman??

Slate flat tiles. I should mention that we have a couple of velux windows on that roof, but the leaks aren’t directly related. Any replacement tiles would need to work with the velux windows.

I’ve no knowledge of slates, but wondering if it would be possible to increase the headlap?

I’m sure one of the roofers will give you a definitive.

I’m a little annoyed with myself that I didn’t notice the issue with the pitch when the extension was built, but to be honest I didn’t know much about anything back then.

Hopefully someone will be able to help and provide advice.

Velux windows go to a minimum 15° the flashing can be changed to suit the tile.
Forticrete centurion go down to 10° amongst others.
Your roof may or may not need re-inforced that would need to be checked.

permavent easy slate. reuse the existing slate

Thanks. The velux windows seem to be ok generally, but I understand that it maybe installed outside of the manufacturer’s specification. The leaks tend to be away from the velux. We did have an issue with one but realised the builder had caught one of the seals with a screw which created a gap. Once we released it it was fine.

I’ll take a look at forticrete and if it requires more support then so be it. Probably better than having to raise the pitch which would be a lot more work.

Datarebal,

Thanks for posting the idea of using permavent easy slate. It seems to be a good option I never came across. Benefit of keeping my slates and batons.