Laying DPC - tips to make it stick!

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Hi All,

Attempted what I thought would be an easy job, and the first job I have putting down new timber in a suspended timber floor - putting a DPC roll across top of the sleeper walls before sitting the wall plate on top.

I laid out a thin bed of mortar (1-2mm, using one of those pre-mixed bags) on top of the wall, what I thought was wet enough, put DPC on top and no adhesion at all, just slid right off even with trying to press down.

Any tips for making it stick? should I forget about the premixed bags and do my own mix 4:1 sand/cement mix? Should it be really wet, my mix was sandy almost instantly despite my thinking it was pretty wet, is 1/2 mm too shallow? should I have used a plasticiser?

Would appreciate any tips!
 
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8mm bed, dpc, 8mm bed, wall plate. If you're short of depth then 8mm bed, dpc, wall plate. The mortar is not to stick things together but to accommodate the different thicknesses of the bricks and timber. When my dad trained to be a bricky he was taught that the mortar was to keep the bricks apart, not to stick them together.
 
If the top of your sleeper wall is spot on the height you want then just roll the dpc on it and chuck the timber on top- gravity is your friend :) .
EDIT Yes 2mm of mortar is too thin for anything.
 
thanks for the advice - rolling DPC out and timber on top, relying on gravity may be the best approach. I don't have much room to build up mortar, may get away with just an 8mm bed but will double check. Could always use metal strapping to secure the wall plate down while I put the joists down, otherwise be worried about it shifting around as I try to get all the joists down.
 
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DPC is held by friction of whatever is above it, not stuck like it's glued.

However, a bed or a few blobs of mortar will hold it if the DPC is pressed down by sliding or rubbing a brick over it
 

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