5mm wide crack coating to cover a whole shed roof.

[Ltnman]

I have a well maintained hand built shed covered in quality felt maybe built around 12-15 years ago. Around 6 years ago I coated the felt with Roof Trade Roof Sealer, which is a solvent based acrylic coating. There was nothing wrong with the roof but I just wanted to add a layer of protection before any problems appeared.

I have now discovered that I have a 100mm x 47mm wood joist that is holding up the 20mm chipboard roof that is wet. Directly above it is a split that is no wider than 5mm.

I am planning to re-coat the roof with Thompson's 10 year roof sealer but on-line instructions say to fill any cracks first but it doesn't say what with. The rest of the existing sealer in in good condition apart from a very small section where the coating has disappeared leaving good felt underneath. This is generally where I step off a ladder and twist my foot.

Question 1. Ideally I just want to coat the roof again with a paint brush that will fill the 5mm gap. Is there a product that a DIYer can lay his hands on to do that job.

Question 2. Assuming I use Thomson's or another product what sort of filler should I be looking for? I just need a very small pot if there is no answer to question 1

 

[mattylad]

A bitumen sealer/paint can be obtained at most DIY stores.

Like https://www.screwfix.com/p/cementone-waterproofing-bituminous-paint-black-5ltr/82914

This is most likely similar to what your going to paint it with anyway, can't you just dob more into the crack and let that dry before coating it all?
Or perhaps seal it with a patch of new felt?

FWIW I'm not a roofer, but I have used bitumen products and they work well.

 

[^woody^]

Acrypol and maybe with flashband across the crack, or on its own.

I doubt a filler will be flexible enough for a crack - which will move.

 

[Mw Roofline]

Acrypol and maybe with flashband across the crack, or on its own.

I doubt a filler will be flexible enough for a crack - which will move.

what woody said. I think acrypol is fine to fill the gap because of the fibres.

 

[catlad]

Acropol recommend using their 100mm wide fibre glass tape for large cracks, in addition to acropol itself.

 

[Alastairreid]

Bearing in mind the felt is coming to the end of its lifespan.

Have a read at this link.

https://www.buildingregs4plans.co.uk/guidance_flat_roof_surface_protection.php

 

[Ltnman]

https://www.buildbase.co.uk/link/1/2815024_31127_t.pdf The tin says it will seal cracks of up to 10mm and mine is 5mm. Would I still be better to put a scrim over the crack?

Good shout guys. Acrypol + comes with the fibres while Acrypol without the plus comes without.

I note the above comment from Alastairreid about end of life felt. Would it still fail with time as I painted it with roof sealer when it was still looking good around 6 years ago. Most of the roof is in shade from the house on a north facing wall. Isn't the whole point of this product to offer a fix for a failing roof including felt?

 

[Alastairreid]

No! Acrypol is a repair compound.
It will buy you more time if you keep patching it.
Ultimately the felt degrades to a point it starts to break apart.