Leak around skylight

Hi,

I have a large building at the bottom of my garden which has been there from before I moved in and we've converted it into a gym/summer room.

The roof is pitched although the angle is very shallow - definitely no more than 20 degrees and has two skylights.

A damp patch inside developed around one of the skylights and so I patched where I thought the leak was on the roof but the damp just go worse.

My neigbour (who knows a bit more than I do) tells me that the covering on the roof is not the correct type - in fact it's some sort of underlay over which the roof covering should be applied.

I've decided to put a proper roof covering up. My question is will roofing felt be okay for this and also how do I seal around the skylights properly so that there are no leaks?

Thanks for any advice.

Tin.

Is the skylight window made by Velux ? or is it a dome type etc ?

Hi Masona,

I think it is a velux but it's definitely not a dome type - it's flat and the body of it sits slightly raised above the roof line.

Velux type windows are not designed for shallow pitches (if I recall correctly the minum pitch used to be 22 degrees, although 20 degrees is the minumum now) and the flashings are not designed for use with roof membranes.

You might consider using a dome type rooflight.

Hi GwaiLo,

Unfortunately cost means that won't be an option...so what's the best I can do with what I have?

Thanks.

Tin.

It's very difficult to know without seeing it,a picture would be great.

As GwaiLo mention the angle of the roof could be the problem for the rain flashing to work properly,I was going to suggest to raise the top of the skylight window up and make a box section into a wedge shape and then re-seal the flashing around the box section with hot bitumen felt,but having said that,I don't know what your skylight window flashing looks like.

Hi Guys,

Just thought I'd let you know what happened with this...

The windows are velux and when I took a closer look at the skylights, there were various soft metal coverings which prevent water getting through. Basically, I took these coverings off (which go all the way around the skylight) and found the underlay had been run up underneath them. I did the same with the roofing felt and I'll check over the next few days if it stops the water leaking through. Given the weather we're having at the moment, this should be a pretty good test!

As for the felt, I used felt which has an adhesive film on the back to make it stick as soon as you put it down...didn't work too well and I ended up having to use clouting nails to secure it. This stuff was pretty expensive (25 quid for 6 metres by 1 metre) - don't think it was worth the money - you live and learn!

Thanks for the help.

It sounds like the felt you used with the adhesive back will have been what is called, Torch-On felt, meaning it is heated up with a gas gun and it melts and sticks as you lay it down on the roof that is why it is so expensive.