Slab built on walls - how to avoid cold bridge.

[MarkH]

The Man came round today to check our sub-grade, waste pipes etc before we pour the concrete later this week. All was good with the plumbing (he didn't seem to pay it much attention for all the cogitation I did about bloody rocker pipes etc...) BUT he noticed the deep layer of aggregate in the smaller downhill section of our build and stated that as the aggregate was just greater than 600mm we needed to pour a slab that overlapped the walls by some amount (he thought 100mm but is confirming tomorrow) and is reinforced with heavier mesh than the a142 we're using in the main part of the house. This is going to mean removing the inside 100mm of the top course (our solid EWI walls are 215mm thick) or removing the whole course and relaying 100mm blocks cut down to slab thickness.

 

I'm wondering about the cold-bridge we'll form by continuing the slab onto the walls like this. Will the EWI (250mm of EPS probably) make the lack of upstand irrelevant or should I look to do something about this new cold-bridge?

[Oz07]

Not something you want to hear at that stage it's going to mess your floor makeup up as ideally you want insulation and screed above this. 

 

[MarkH]

6 hours ago, Oz07 said:

Not something you want to hear at that stage it's going to mess your floor makeup up as ideally you want insulation and screed above this. 

 

You're not wrong. But we don't plan to have insulation or screed over the slab - it's all below. Still screws us up though. I've come up with a path ahead I think.

 

[Ferdinand]

Um.

 

Remembering my de Bono, can you dig it back to 595?

 

(this may be a silly or impossible idea)

Edited October 11, 2016 by Ferdinand