torch on felt
- Thread starter omph
- Start date
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You can torch over existing felt if the deck is in good condition.
Cut out any blisters and prime the old felt and torch over it with 4mm torch on cap sheet.
The old felt melts down and becomes sticky when heated, this bonds the new cap sheet wirh the old.
If the roof is wet, dry it out with your gas torch.
The finished job will probably look a bit humpy and bumpy with maybe a few wrinkles here and there but it will keep the rain out.
The best option would be to strip off the existing felt and redo with torch on underlay and capsheet on top.
Cut out any blisters and prime the old felt and torch over it with 4mm torch on cap sheet.
The old felt melts down and becomes sticky when heated, this bonds the new cap sheet wirh the old.
If the roof is wet, dry it out with your gas torch.
The finished job will probably look a bit humpy and bumpy with maybe a few wrinkles here and there but it will keep the rain out.
The best option would be to strip off the existing felt and redo with torch on underlay and capsheet on top.
Last edited:
Thanks, very informative.
By blisters I assume you mean humps, of which I have none. The top layer of felt does have stretch marks and some cracks along the edge, should I pay special attention to those areas, or just felt straight over them ?
Also, when you say primer, what kind of primer should I use ?
And how much propane will I need for about 7m^2 + drying out the wet felt ?
6kg keg of gas will be plenty.
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Stretch marks are caused by expansion and contraction during summer and winter weather.
Once they are heated by the torch they melt down and become sticky, when you roll your cap sheet over them, the melted bitumen will fill them in.
If there are pools of water on the roof you brush them off and dry the felt with a mop.
You can then dry the felt properly using the torch, then prime the toof with primer and wait for it to dry, you then torch on your cap sheet.
To get the torch on cap sheet you would be advised to go to a proper roofing supplier, you can get felt in DIY stores like B&Q but their stuff is crap.
Also by going to a proper roofing supplier they will have everything you need including primer, what you want is 4 mm torch on cap sheet and a tin of primer.
Thanks!
When drying out the felt with the torch won't that melt the felt ?
No, you only need to go over the felt lightly with the torch.
You will see the damp on the felt evaporate, on felting torches you can adjust the flame if you wish to avoid melting the felt but you should not need to.
C.S.Lewis?
Thanks! How do you cut the felt ?
Use a Stanley knife with a hooked blade.
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