Sealing a gap that's opened on a flat roof

[Bonefish Blues]

We've got a roof weeping. I can see exactly where, and it's where the sealant between an edpm area and a conventional felt has opened up. Specifically it's where the two materials overlap and both curve up to the vertical to run up a small upstand and behind some fascia boarding.

It's likely that I'm simply going to bite the bullet and redo the whole roof in edpm next year, so I'm looking for an interim solution, I assume that I can deliver from a caulking gun which will work damp and stick to both felt and edpm.

Any thoughts?

[Pheo]

CT1?

[Bonefish Blues]

I've been puzzling over the difference between CT1 and OB1. The latter also produces a tape that may be useful as an extra barrier after sealing, I thought.

[bimsb6]

Bonefish Blues said:

I've been puzzling over the difference between CT1 and OB1. The latter also produces a tape that may be useful as an extra barrier after sealing, I thought.

Ct1 is a good sealant and ob1 is a character from star wars .

[Simpo Two]

Sikaflex? Sticks like st.

[Belle427]

Must admit the first thing I tried CT1 on I was not impressed, I do see it recommended a lot though.
Large gaps will be difficult with sealant, you may need to use flashband.

[Aluminati]

You won’t stick anything to EPDM that will last long. And EPDM won’t stick to bitumen based membranes.

There should be an isolation kerb between the two.

[trickywoo]

This may be a bodge too far but could you vulcanise (with bike puncture repair) something to the epdm that has a top surface that could be joined with the felt?

I’ve had good results with flashing tape which may work if you can get the epdm bondable.

[Byker28i]

Can you use the Thompsons products?

I resealed our flat roof using the 10 year roof seal
https://www.screwfix.com/p/thompsons-10-year-roof-...

Fixed a leaking edge using the emergency repair. It's a thicker gloop
https://www.screwfix.com/p/thompsons-emergency-roo...

[OutInTheShed]

Prime with lots of bitumen paint or roofing adhesive and apply flashband with a hot air gun.

It's a bodge and won't last long, but it's all you can do.
EPDM is very nice but joints and details are a problem.

I expect the join has failed due to movement, so will fail again.

[Bonefish Blues]

OutInTheShed said:

Prime with lots of bitumen paint or roofing adhesive and apply flashband with a hot air gun.

It's a bodge and won't last long, but it's all you can do.
EPDM is very nice but joints and details are a problem.

I expect the join has failed due to movement, so will fail again.

This sounds the most long-term temporary fix! Your movement comment is correct - whilst the edge where EDPM is bounded by the felt has (correctly, I think?) a screwed metal strip over the top, that strip can't bend to fit the curve of both materials up to the vertical (and indeed wouldn't have anything to screw to between the vertical & the horizontal), so that bit looks like it has been a bodge - classic ha'pth of tar which has failed after 5 or so years. I guess what really should have been done is the curve to the upstand should all have been replaced by EDPM, similarly jointed to the felt with a strip that can be sealed properly on a horizontal surface?

I think the latter seems the lowest cost way to get a decent long term fix, but your method should at least get me through winter without any more internal puddles.

Edited by Bonefish Blues on Tuesday 4th November 11:15

[The Gauge]

I've no experience with edpm but with felt whenever I've had to repair any joints that have come undone I've used a tin of bitumen, warmed up if needed to make it runny enough to spread/pour. I decant some into a kettle and use the wifes favourite kitchen silicone spatula and ladle to apply, pouring it along the joint and then spreading it underneath, and then weighing down afterwards with some bricks. Some wide enough flashband tape applied on top would also help, and hide the mess I've made with the bitumen

[DonkeyApple]

Bonefish Blues said:

We've got a roof weeping. I can see exactly where, and it's where the sealant between an edpm area and a conventional felt has opened up. Specifically it's where the two materials overlap and both curve up to the vertical to run up a small upstand and behind some fascia boarding.

It's likely that I'm simply going to bite the bullet and redo the whole roof in edpm next year, so I'm looking for an interim solution, I assume that I can deliver from a caulking gun which will work damp and stick to both felt and edpm.

Any thoughts?

Peel back as far as you can and dry the surfaces as best as possible. A heat gun on a low setting might be best. Then use tigerseal to bond it all together. Might be worth then running a bead of tiger seal down the whole length of the join and smearing it in. Grim stuff to get on clothes but will stick edpm to the felt.

[Bonefish Blues]

DonkeyApple said:

Bonefish Blues said:

We've got a roof weeping. I can see exactly where, and it's where the sealant between an edpm area and a conventional felt has opened up. Specifically it's where the two materials overlap and both curve up to the vertical to run up a small upstand and behind some fascia boarding.

It's likely that I'm simply going to bite the bullet and redo the whole roof in edpm next year, so I'm looking for an interim solution, I assume that I can deliver from a caulking gun which will work damp and stick to both felt and edpm.

Any thoughts?

Peel back as far as you can and dry the surfaces as best as possible. A heat gun on a low setting might be best. Then use tigerseal to bond it all together. Might be worth then running a bead of tiger seal down the whole length of the join and smearing it in. Grim stuff to get on clothes but will stick edpm to the felt.

What consistency is Tiger Seal?

[DonkeyApple]

Bonefish Blues said:

What consistency is Tiger Seal?

About the same as decorating caulk, maybe a little thicker. Very, very sticky but easy to spread with a a palette knife etc.

[SteBrown91]

You can buy a silver paint for roofs that s got fibreglass fibres in it which might provide a temporary bodge.

Think this is the stuff

https://www.toolstation.com/evercryl-roof-repair/p...

[Pheo]

Bonefish Blues said:

I've been puzzling over the difference between CT1 and OB1. The latter also produces a tape that may be useful as an extra barrier after sealing, I thought.

Pretty sure one is just Screwfix ownbrand vs the original