Questions on laying concrete floor

[gwebstech]

Hi all

 

Im hoping to lay the concrete floor soon on this new build.  Am i mistaken or have i seen somewhere that when you lap the visqueen over the outside course, that the outside course is slightly higher - prob 1 brick - than the inside course?

 

Also im assuming that you ALSO need a separate DPC - the black thinner roll type - that goes on top of the visqueen? and that is used as the correct DPC?

 

thanks

[Oz07]

Outside would be 1 brick lower if you are extending dpc across the cavity, creating a fall outwards, with weepholes. Not sure on the specific requirements for this, i've had to do it before as BCO suspected methane could be present (not radon). It's not normally done with the floor DPM anyway if spanning cavity, usually a roll of DPC as you say.

[gwebstech]

13 hours ago, Oz07 said:

Outside would be 1 brick lower if you are extending dpc across the cavity, creating a fall outwards, with weepholes. Not sure on the specific requirements for this, i've had to do it before as BCO suspected methane could be present (not radon). It's not normally done with the floor DPM anyway if spanning cavity, usually a roll of DPC as you say.

thanks, my architect told me that the visqueen is effectively a 'radon barrier' anyway, so thats one less thing i have to worry about

[Brickie]

Assuming a level site,your dpc will be same as finished floor level (give or take a few mm.) Your membrane laps in under the dpc o the internal skin. Internal & external dpc will be the same level. If there’s a dpc tray it goes up from the external dpc height by one block course (225mm) to the inner skin. The reason your slab is normally down from dpc height is to allow for the floor make up.