Linking DPM to airtight layer

[bissoejosh]

What is the preferred method of linking a floor level airtight layer (DPM/Radon in this instance) to the wall layer (Vapourboard or similar coated OSB)?

 

My plan was to bring the DPM up the inside face of the external walls and tape it to the Vapourboard but I've seen several drawings where the DPM looks to head out under the sole plate instead, in which case how is the sole plate sealed for air tightness?

 

Apologies if this is a basic question but I'm struggling to find confirmation with google/forum searches.

[A_L]

49 minutes ago, bissoejosh said:

 

My plan was to bring the DPM up the inside face of the external walls and tape it to the Vapourboard but I've seen several drawings where the DPM looks to head out under the sole plate instead, in which case how is the sole plate sealed for air tightness?

 

Non setting mastic or sometimes expanding tape. Could use 100/150mm wide strip of DPM polythene fixed with ORCON F to both floor and wall.

[bissoejosh]

10 minutes ago, A_L said:

 

Non setting mastic or sometimes expanding tape. Could use 100/150mm wide strip of DPM polythene fixed with ORCON F to both floor and wall.

So take the DPM out the building under the soleplate then add a second layer / strip on the inside which joins the floor to wall?

[MikeSharp01]

On the garden room of our build I have tried a couple of approaches in readiness for the house. In the end I found the best seal was to seal the airtight membrane to the floor, I used THIS tape, double sided bitumen. So I brought the airtight membrane down the walls and folded it out into the room by 30mm having first cut back the sole-plate DPM to the edge of the sole-plate (on this inside only) I put the TAPE in under the fold and then nailed a batten to the sole plate, compressed down onto the membrane using jack cramps. The floor is power floated so quite flat but the tape can take up small wrinkles and the batten forces it all closed. No leaks that I can find. ONE WORD OF WARNING this building is not the house or subject to the same strictures as the house but I will use this method on the house as I am very happy with it

[bissoejosh]

That sounds more like what I had in mind.  When you say sole plate DPM is that the same as your floor one or a separate strip?

[Bitpipe]

We have a MBC build and they used two separate products here - each is doing a separate job.

 

N.B. we also had a basement so slightly different setup to normal slab foundation but hopefully the principal is the same.

 

The DPM strip went down on the concrete perimeter wall and the (much wider, 1m or so) yellow airtight strip went on top of this and the soleplate went on top.

 

The DPM came out under the exterior wall and I dressed it down onto the EPS underneath.

 

The airtight fabric was taped to the inside of the basement wall by MBC and taped to the inside of the green airtight board on the inside wall of the frame - i.e. it wrapped from the inside of the basement wall, out and around the soleplate and back inside.

 

This detail was repeated on the interface between ground and first floor.

[bissoejosh]

9 hours ago, Bitpipe said:

 

The airtight fabric was taped to the inside of the basement wall by MBC and taped to the inside of the green airtight board on the inside wall of the frame - i.e. it wrapped from the inside of the basement wall, out and around the soleplate and back inside.

 

This is exactly what I intend to do between our blockwork lower GF and timber frame upper GF in order to tie the two together - out and around the posi joist top chord before tucking into the wet plaster coat on the masonry below. For my upper GF where we have our beam and block my thinking is DPM/Radon out under the sole plate to cover the radon in the walls aspect. I'll cut a separate strip of DPM as per @A_L suggestion to make the join between airtight board and the floor DPM.

 

Anyone see any issues with this?