Repairing a felt roof

[skellem]

Right, I see there are loads of topics on felt roofs, but none answer my question!

I built a felt roof on my shed (rather a large shed though!) and I built 2 skylights as well. One of these is leaking like a sieve, so i want to remove it and patch the hole. I don't want to redo the whole roof as it was only done a year ago.

The way I constructed it was one layer of underfelt nailed to the boards at 100mm centers, the second layer of underfelt was glued to the first using cold applied glue, then the top layer of felt was glued to the second.

The way I invisaged repairing it was to remove the rooflight and fit a board into the gap, supporting it from underneath. Then nail a layer of underfelt onto the board, while overlapping it and glueing it in place.

The main question is with the top layer. The patch obviously has to be a bit bigger than the hole in the original felt (say 300mm overlap each side?) Can I use the same cold applied glue to stick the patch onto the original roof, bearing in mind it has the small chippings? Should I try and rub these chippings off first so it sticks better? Or is it better to use a hot glue? (I've never used a hot glue and not too sure how it's applied etc)

Any help is appreciated!

 

[chappers]

you should be able to get away with the cold glue but I would rub away the worst of the chippings or alternatively you could use torch on felt, but its about £30 a roll.
Give it a go its already leaking now what have you got to lose

 

[skellem]

Thanks Chappers, I actually have a bit of spare felt that I saved when I was doing the roof, so I'd like to use that to keep it looking the same.

The one thing that is worrying me is that it is so wet at the moment I'm not sure how to get the roof dry to lay the new felt. Can I just use a hair dryer and spend an hour up there drying out the felt, and then lay the new felt? Does it need to be completely dry for the cold glue to work?

 

[chappers]

I believe it does have to be dry, think you might stuggle with a hair dryer, probably better off with a roofing torch if you can hire or beg one.
Worth atry with the hair dryer though, just don't get the glue on it or the misses will go spare.

 

[skellem]

Well, I attempted the job today. I found that all of the self adhesive flashing I had sealed the roof light with had come unstuck and the water was just gushing in underneath! The thing that really pee's me off is that I specifically called the manufacturer and asked if I needed to use the primer on roofing felt. They said NO! Well, it didn't work, the whole lot just peeled away as if I didn't even peel the sticky backing off before I stuck it down!!

So a friend and myself used a hairdryer and a blowtorch (thanks chappers, a hairdryer does work, but it takes aaaages!!) and managed to get the whole area dry. Then we applied cold glue to the whole area and I stuck down a layer of underfelt and nailed it down well. We started to apply more glue to that lot to stick the top layer to, and the heavens opened up! I ended up covering the whole lot with a large tarpaulin.

Please all hold thumbs that we have some dry weather tomorrow in Tadley

 

[masona]

Does it need to be completely dry for the cold glue to work?

I think this is where your problem is, you may think the roof area is dry and warm but the moisture is still getting out. The whole timber/board thickness must be 100% dry and not just the top area. As chappers said a roofing torch or blowlamp may be the best way.

 

[skellem]

Well, I did use a blow torch to dry the area, and it has worked! I have managed to seal the whole roof light and it doesn't leak anymore. (We have had HUGE amounts of rain over the last week and it has held up fine )

I also dried the whole underneath of the roof from the inside to make sure there is no more moisture there, so fingers crossed...