cavity trays and flat roof abutment
Discussion
I have a flat roof that abuts a vertical wall.
I installed 'refurbishment' type cavity trays which are the type with no lead attached, just a clip that keeps the spacing while the motar goes off.
The clips are then removed and the lead flashing goes in under the lip of the tray.
So my question is, what's the best way to seal the joint between the tray and the lead? Manthorpe (the tray manufacturer) doesn't say exactly what to do. I presume I could get a thin bead of leadmate under the tray and push the lead into it?
To get the lead in under the tray, it needs to go 2 inches into the wall, which is further than normal?
Also, there is a weep in each tray, but using leadmate to fill in the joint afterwards makes a water tight seal, basically keeping the water pooled in the tray until it finds the weep. would a motar joint between the lead and the brick not be better as it will allow moisture to escape quicker?
(I posted this on www.diynot.com too if it seems familiar)
I installed 'refurbishment' type cavity trays which are the type with no lead attached, just a clip that keeps the spacing while the motar goes off.
The clips are then removed and the lead flashing goes in under the lip of the tray.
So my question is, what's the best way to seal the joint between the tray and the lead? Manthorpe (the tray manufacturer) doesn't say exactly what to do. I presume I could get a thin bead of leadmate under the tray and push the lead into it?
To get the lead in under the tray, it needs to go 2 inches into the wall, which is further than normal?
Also, there is a weep in each tray, but using leadmate to fill in the joint afterwards makes a water tight seal, basically keeping the water pooled in the tray until it finds the weep. would a motar joint between the lead and the brick not be better as it will allow moisture to escape quicker?
(I posted this on www.diynot.com too if it seems familiar)
roofer said:
We are installing type e cavity tray at the moment. We put the flashing in first and bed the tray on it. Not sure what tray you have, but sounds hard work .
Hi Roofer, yes sounds like the sensible way to do it!The trays I have are these:
http://www.manthorpe.co.uk/Building/Products/Cavit...
Their datasheet says:
The GW294 Refurbishment Horizontal Tray is designed
to provide protection where a new horizontal roof
abutment meets an existing wall. It can also be used
where the original system has been found to have
degraded or even left out of the wall construction.
Alternatively it can be used in new build horizontal
situations or in conjunction with the GW295 Horizontal
Tray. Integral stop ends and a hook feature remove the
need to overlap the trays giving a total effective length
of 450mm.
The tray has a unique front mortar clip that can be
removed at any time once the mortar has set leaving a
25mm deep aperture into which the lead is inserted and
secured with lead wedges.
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