Tagged: dpm dpc external wall insulation
1 October 2018 at 5:26 pm #48945
I am currently working on the detailed designs for our circa 1940 ex local authority semi in cornwall.
It is currently an uninsulated solid wall (pot block (sometimes called 9″ cavity block) basically concrete blocks in figure of 8 with hollows inside some stuff about these on joseph little forums)
Solid uninsulated floor.
Double glaze failing UPVC windows with only 2 trickle vents in whole house.
Open fire place, oil combi boiler and rads.
Some loft insulation.
The ground falls from the front of the property where it is about 150 ish below floor level to the back where it is 700 below floor level.
QUESTION (more to come I am sure!)
We intend to either dig out the existing concrete slab insulate and lay new slab / screed and dpm or insulate over existing slab and use floating floor. We intend to externally insulate and go below ground with this.
The property doesnt seem to have a dpc in the walls. So nothing to connect a new dpm to. Is there a risk of rising damp (not really any evidence of rising damp at moment only condensation) if we externally insulate and stop dpm on inner face of wall and tape to internal plaster/ render. Should I be tanking the inside of the wall up to say 1m?. (external wall spec says to tank out side below dpm and use XPS but I read on green building forum that can use EPS even below ground). We also have radon to think about being in cornwall. Will put sump in and think MVHR will help reduce risk.
Also on outside where external wall insulation goes down below ground should we have gravel perimeter or concrete and try to slope away from building (the later is possible but more difficult at front where ground slopes towards building.
Thanks in advance
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