Passive raft with single stud wall

[Andrew]

Is there any point using passive raft foundation with a single stud wall construction?

 

As I understand it the normal detail is to use a twin stud wall that ends up with the insulation in the wall sitting atop the insulation uptick at the edge of the foundation and the inner stud carrying the load atop the raft. I can't see how this could work with single stud as the stud will have to sit on the reinforced edge of the raft to support the wall. 

 

Just looking for a bit of validation and any potential alternatives. Thanks.

[TerryE]

IMO -- and it is a personal one -- our MBC passive raft with embedded UFH worked out cheaper than the equivalent traditional foundations + beam+block + insulation + UFH and screed and was a lot less hassle, but the caveat here is that doing a passive raft well is a skilled job and you risk being let down badly if the build crew aren't good at what they are doing -- in that everything has do be right for the pour and once started the crew is working against the clock.  OK we also have a twinwall, but our supplier also does single-wall solutions so it can be done.   We also had a complication with our slab because of our external skin and a potential thermal bridge that the SE designing the slab missed.  See this post:

But the final result looks good (sorry for the cloudy day).  The engineering brick plinth wraps the outer EPS 300 and the outer stone skin sits on a foamglass layer to complete the thermal isolation of the slab.  The entire house is heated by a single immersion heater element in what is known as a Willis heater, but that's a separate discussion.

 

 

Edited December 11, 2018 by TerryE

[Gone West]

5 hours ago, Andrew said:

Is there any point using passive raft foundation with a single stud wall construction?

 

As I understand it the normal detail is to use a twin stud wall that ends up with the insulation in the wall sitting atop the insulation uptick at the edge of the foundation and the inner stud carrying the load atop the raft. I can't see how this could work with single stud as the stud will have to sit on the reinforced edge of the raft to support the wall. 

 

Just looking for a bit of validation and any potential alternatives. Thanks.

We have an Isoquick PH insulated raft foundation. We have a single stud wall, but the 'stud' is a timber I-beam. The I-beam sole plate sits on the edge of the concrete and all the Icynene  insulation is within the I-beams. There is 15mm OSB3 racking on the outside of the I-beams with external rockwool insulation on the racking board which joins with the EPS upstand.