Repair felt roof after removing boiler flue?

[a546345]

The photo shows what's left after I've removed most of the flue which is not needed any more.

This cold-roof was replaced in around 2007 by the previous owners of the house. I guess the flue was already there, because the metal in the photo is under the over-boarded plywood.

My plan is to
1. Cut the protruding metal section into strips so that it can be folded down flat. I don't think I can easily remove it. The metal section is supported by another layer of plywood with just the flue hole cut out. You can just see that layer through the hole.
2. Remove all loose material.
3. Cut a circular piece of plywood to go on top of the metal and bring the level up to the top of the existing plywood. Stick it down with CT1.
4. Cut a patch of felt 50mm bigger on each side than the existing rectangular hole, use plenty of adhesive on the plywood and the underside of the felt patch.
5. Add more adhesive on top of the felt patch around the edges.

I have some leftover shed felt which seems quite thin. Can I use that, or should I get something better? If so what?
Will one layer of new felt be enough or should I use a second patch larger than the 1st?

Does this sound like it will work, or will it be more complicated, and I should get someone in?

 

[noseall]

The photo shows what's left after I've removed most of the flue which is not needed any more.

This cold-roof was replaced in around 2007 by the previous owners of the house. I guess the flue was already there, because the metal in the photo is under the over-boarded plywood.

My plan is to
1. Cut the protruding metal section into strips so that it can be folded down flat. I don't think I can easily remove it. The metal section is supported by another layer of plywood with just the flue hole cut out. You can just see that layer through the hole.
2. Remove all loose material.
3. Cut a circular piece of plywood to go on top of the metal and bring the level up to the top of the existing plywood. Stick it down with CT1.
4. Cut a patch of felt 50mm bigger on each side than the existing rectangular hole, use plenty of adhesive on the plywood and the underside of the felt patch.
5. Add more adhesive on top of the felt patch around the edges.

I have some leftover shed felt which seems quite thin. Can I use that, or should I get something better? If so what?
Will one layer of new felt be enough or should I use a second patch larger than the 1st?

Does this sound like it will work, or will it be more complicated, and I should get someone in?

View attachment 420275

You are putting a lot of faith there with DIY adhesive. I'd leave that to the (torch-on) pro's.

 

[stevie888]

Shed felt is cheap nasty stuff. A proper felt roof is at least 6mm thick with 3 layers.

You could DIY with care: get a roll of 2mm torch on. You'll be able to handle small pieces with a decent blow lamp. Make good the ply as suggested then cut bits of felt to infill the hole to bring you up level. You can now patch over the lot. Personally I'd lap 100mm and then another and then another. Take special care to get the edges rolled down tight. It won't look pretty but if the roof is 20 years old then you will be replacing it in the future.

 

[^woody^]

Nothing wrong with a cold adhesive repair (ie not torch on).

You need to ensure that the area is built up to ensure that water does not pond in the repair. The top layer can either lap the sides, or you can build the area up, seal the joint, and then fit a cover strip around the perimeter.

Best to screw down any ply infill, not just rely on CT1.

Select your felt based on how long you need the repair to last in context of the surrounding felt's life left.

 

[a546345]

Thanks for the replies. All done now. I got someone to do it. They cut out the circle to a rectangle, removed the metal sheet, put a section of ply in, then some underlay and torched on some nice thick roofing felt.

The peace of mind of not having to worry about it every time it rains is worth it to me!