sealant for between concrete roof and brick wall

[Scully]

Weathermate is good as it stays pliable and doesn’t really set, and you can apply it in the wet. I’ve known many folk use clear silicone to remedy such matters, but doubt either would be long term.

Once drier weather is here I would completely redo. 

 

[JKD]

Re the dip,,,, can sort of see what you're describing. Still doesn't look right 🤔

The two separate lead flashings are basically doing nothing,,,, but 'sucking' water back to the roof/wall junction using capillary action. You can use as much sealant as you like,,,, that sealant is the only thing stopping the ingress. On a 'flat' roof that system will not work. I've seen pitched roofs with the same issue.

As it stands, if you take the lead away and seal the 'junction', that will do a temporary fix.

TBH, for a proper fix, I would wrap it with a roofing sheet layer,,,, 3 layered mineral felt, rubber, fiberglass. With firring pieces and 18mm ply, and 18mm ply verges to keep things not protruding past the existing roof area.

Edited February 16, 2020 by JKD

[paul1966]

thanks, i am only looking for a temporary fix as i am planning in the future to put a warm roof system on top of the slab so when that is done this problem should go away too.

[JKD]

OK,,,, now you've told us your future plans 👍

Wait until it's dry weather,,,, carefully lift both lead flashings,,,, you can do it in sections and support the lead with timber,,,, dry area beneath with a hot air gun/paint stripper, being careful near the lead,,,, layer lots of lead/gutter sealant to the area,,,, re-dress the lead.

That should do the job until your improvements,,,, hope that helps 😉

If you look carefully you can see the small i-beams in the concrete slab.

Edited February 16, 2020 by JKD

[Remimax]

5 hours ago, paul1966 said:

its just a bare concrete slab, its darker due to the rain, the dip in the picture is just a shallow pool of rain water not a sunken area. i have been up on the slab and its in good order, its just the lead flashing that needs looking at, you are correct it has been repaired before. I think i need to lift the flashing up and see whats underneath if anything.

you'll never get a seal on it if its just flashing sat on the slab ,no amount lead mate will fix a bodge.

lead moves when it warms up hence the max length rule when installing flashing.

you could do the whole thing in felt with a 45degree fillet at the wall slab junction with continued up stand of felt.

if the concrete is flat enough you could prime with G4 add your edge trims bonded or fixed and grp the whole thing.

or you could board onto the concrete slab with vapour barrier and or kingspan then trim and grp the whole lot with 45 fillet upstand.

 

[WalkedUp]

If there is a parapet then my only advice would be to price for insulation above as a warm deck with falls and covering in a single ply membrane turned up the parapet and any wall abutments. Get a few quotes from specialist roofing contractors and then make a decision. 

You can do it badly with lead and sealant to try to slow the water ingress and decay, but it will not work long term. The original construction is typical an old garage roof etc, a space not intended for inhabitation. If/when you sell it is likely/possible the buyer’s surveyor will notice. 

[Taileron]

My neighbors had exactly the same problem. It cost £850 for the entire roof to be done and came with a 25 year guarantee.

Edited February 17, 2020 by Taileron

[WalkedUp]

Funnily enough I was going to send a link to Firestone. We historically specified Sarnafil for single ply but over the last few years have had some projects VE’d or D&B’d to Firestone. It is actually a great product, and the approved installers have been well trained. I had to condemn one roof, it was done badly and bubbled. The client had paid a pal cash (always alarm bells) to do it but not sure he was actually an approved installer, the replacement by another approved installer was perfect however. 

Edited February 17, 2020 by WalkedUp