Cavity tray over continuous DPC

acurachris

acurachris

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Hi

I have a 600mm gas DPC bridging the cavity and I need to install a cavity tray with this. I started to use some polythene DPC as the cavity tray and mortared 20-30mm of this DPC cavity tray on top of the gas DPC of the external leaf.

I'm worried in case any water seeps under the cavity tray and then sits on the continuous DPC, dropping back to the inner leaf. Also worried about this issue at the corners as they are looking awkward to form!

Is 20-30mm enough 'tuck' under the external bricks above the DPC or does it need to be more?

How much water is likely to penetrate through the external wall? Am i over worrying?

I'm considering re-doing the DPC and cavity tray with pre-formed units although my concern is attaching the plastic cavity trays to the DPC and the bricks.

Cheers for any help.
 
Where are you putting your cavity trays?
Gas membrane detailing below.

membrane-gas.jpg
 
Hi

Gas DPC across outer brick, bridge cavity, over inner leaf (all level) then down 150mm, and 150mm on to block and beam floor for attachment to gas membrane later.

There is a patio door going in too so the level DPC makes more sense doesn't it?
 

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corner detail cut summat like this....[GALLERY=media, 102267]Corner Deet by noseall posted 9 Dec 2018 at 7:07 AM[/GALLERY]Except a straight cut on the corner (top sketch oops).
 
Hi noseall

I think i can still make that cut as i've left the dpc to run right into both corners. Where the two meet in the lowest corner of the join will be where any water is going to get through I suppose as this can't be tucked under the external brick (if i understand you right).

Is the 20-30mm tuck under the external brick going to be enough?

Cheers
 
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