Repairing a felt roof

[citoyen]

The felt roof of our conservatory is leaking due to the felt deteriorating. I did some emergency repairs with a tin of repair compound but it would be stupidly expensive to properly cover all the bits that need patching that way.

We have a couple of rolls of lightweight shed roof felt in reserve - might be enough to cover the area. I'm thinking of laying it over the existing felt as a short-term fix until I have the time/energy/money to do the job properly. I think I have a tin of adhesive as well. Does the yacf diy expert panel reckon this sounds like a sensible plan? Any caveats and pitfalls I should be aware of?

At the edge where it joins the house, it is overlapped by the roof tiles, so no need to worry about flashing - I've checked and the roof tiles can be moved/lifted to tuck the edge of the felt under them.

[mrcharly-YHT]

Felt is horrible stuff. Dirty, unpleasant to work with, tears at the slightest provocation.

Personally prefer to treat it as a sacrificial/protective layer. If there is the slightest bump under it, that will wear to a hole.

If you have some sheet plastic (or can get some cheap), I'd be tempted to lay that over the existing felt, then put your lightweight felt on top.

Sweep the existing felt clean of all debris first.

[rafletcher]

Get sone plastic DPC to lay first, then your new felt over, if you’re worried about durability. However I’ve felted over felt on our shed with no issues. Used the cold tar to seal a good 6” at the overlaps and edges. Plus used mastic impregnated tape at edges as extra sealing. It lasts around 6 years. Next time I promise myself I’ll put roofing sheets on 

[citoyen]

Felt is horrible stuff. Dirty, unpleasant to work with, tears at the slightest provocation.

Agreed. Long-term plan is to replace it with EPDM or fibreglass, but for now I'm looking to do a cheap, short-term fix that will at least get us through the winter.

If you have some sheet plastic (or can get some cheap), I'd be tempted to lay that over the existing felt, then put your lightweight felt on top.

With both you and rafletcher suggesting this, that sounds like a recommendation to me! Would you bond the plastic/DPC layer?

Sweep the existing felt clean of all debris first.

Of course.

[rafletcher]

I’d staple the DPC along the top edge and sides, assuming there’s wood below the felt.

[citoyen]

Turns out I didn't have as much spare roofing felt as I thought I did, so would have needed to buy more, plus the state of the existing roof means laying new felt on top of it probably wouldn't be the best idea anyway.

So, after much deliberation and internet research, I took a different approach - went over the most damaged bits with either roof sealant or Gorilla patch tape, then painted the whole roof with Black Jack weatherproof paint.

The paint is mad stuff - has the consistency of porridge and you need to keep stirring it (really could have done with a paint version of a cement mixer). Also glad I bought a cheap disposable brush for the job - cleaning it out afterwards would have been far more trouble than it's worth. Anyway, I finished the job this afternoon and it has just started raining, so I guess I'll find out soon enough if it has done the trick. Will keep you posted, in case anyone is interested.

[citoyen]

Will keep you posted, in case anyone is interested.

As promised... today and yesterday we've had the first proper rain since I did the repair job and it seems to be holding up - no water coming through the conservatory ceiling!

So yeah, Black Jack weatherproof paint. Recommended.