Extensions Question

Cavity tray dpc over joists

Hi, could someone tell me if you need a cavity tray for the floor joists to the bedroom floor? There is one built in for the lintel that's underneath the joists but does there need another one built in for the joists thx

2 Answers

Best Answer

If joists are to be built into a wall then I'd usually wrap the ends of them in DPC using staples to fix it with. Or at least treat the ends with preservative especially if they've been cut. I'd also fix some nails to act as spikes as joists have a tendency to shrink after construction whilst drying out and could become loose.

Answered 23rd May 2012


Member since 23 May 2012

The cavity tray at the lintel is there becuse the cavity is bridged. Your joists should not protrude through the cavity and penetrating rain is supposed to run down the inside of the outer leaf and seep through the brickwork, below your horizontal DPC near ground level. So no! you dont need a cavity tray at chamber joist level.

Answered 17th May 2012

DJ Building Design

Member since 15 Sep 2011

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