DPC under stud wall on insulated slab foundation?

[BotusBuild]

Do I need to install a DPC under a stud wall that will sit on an insulated concrete slab foundation?

 

The insulation is 240mm thick Jackon Atlas (closed cell insulation), then a Radon barrier and then the 250mm slab

[Mr Punter]

Yes you may as well for the very low cost.  Slab will be moist for a long time.

[Moonshine]

2 hours ago, BotusBuild said:

Do I need to install a DPC under a stud wall that will sit on an insulated concrete slab foundation?

 

yes you do, 

 

"Dpcs should be provided below timber partitions where directly fixed to floor slabs, even if there is a dpm beneath the slab. This is to prevent residual moisture in the concrete affecting the timber."

 

https://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part6/section3/sitework.htm

[BotusBuild]

I thought the answer might be Yes.

 

Reaction: Feck! 🙂 

"Hey, get those acroprops out again!!" 🙂 

[nod]

We always do it when fixing metal studs 

[Dave Jones]

4 hours ago, BotusBuild said:

I thought the answer might be Yes.

 

Reaction: Feck! 🙂 

"Hey, get those acroprops out again!!" 🙂 

 

if the stud is already in I wouldn't worry about it.

[deancatherine09]

We have MBC on site at the moment and they have put DPC under all stud walls even though there is a DPM under the concrete in the insulated raft 🙂

[Iceverge]

I also wouldn't worry about it.

 

In fact I'm against it. Putting in impermeable membranes  "just because" is a bad plan. 

 

When building my garage, TF on blockwork, I put one DPC under one sole plate. It was saturated as the moisture was trapped in the gap between the timber and the DPC. Mostly from rain during construction mind you .On the rest I didn't bother and they got wet but dried super fast in comparison. 

 

You're not trapping water in there permanently. I didn't bother either for the few stud walls in the house we have and absolutely nothing went wrong.  Timber never got wet. 

 

 

[Dave Jones]

it is an NHBC requirement.

 

https://nhbc-standards.co.uk/6-superstructure-excluding-roofs/6-3-internal-walls/6-3-13-damp-proof-courses/