No residual cavity space left!

[Sunil237]

Another problem!

My builder was supposed to build with a 125 cavity and use 115mm ecotherm full file cavity insulation t&g leaving a 10mm gap... 

They have built to dpc and built all the block work but there's no 10mm gap once you place a brick on the dpc

 

The 10mm gap is to prevent transfer of moisture but it's literally going to be touching the boards

 

Is this an issue and can anyone provide an alternative insulation that would work?

I really don't want to compromise the u value as I am going for a heat pump

 

I need them to keep on track and start bricklaying tomorrow! He's only just told me this is going to be the case today

[Russell griffiths]

It’s about time you got rid of them. 

[gravelrash]

is dpc at floor level? if so he could possibly overhang the inside or outside wall block 10mm all round (or 5mm on each)  to gain back your cavity size. 

[nod]

Your Architect is at fault 

Not the bricklayer 10 mil is not enough 

Even if the brickwork and blockwork is absolutely perfect 10 mil isn’t enough room 25 is tight but 50 is better 

Im surprised no one has pointed this out 

[ADLIan]

Not really the architect’s fault. Fault lies more with the insulation manufacturer for developing a system that needs this level of dimensional tolerance.

[jayc89]

Our Architect wanted to go 90mm Kooltherm in a 100mm cavity which I pushed back on. We ended up with a 150mm EPS full fill instead. 

[gravelrash]

On 20/01/2025 at 17:11, jayc89 said:

Our Architect wanted to go 90mm Kooltherm in a 100mm cavity which I pushed back on. We ended up with a 150mm EPS full fill instead. 

I used 220mm eps full fill which gave me a wall u value of 0.135 at a third of the cost of kingspan boards.  There is a white paper which Kingspan agree with that states that due to +/- 5mm dimension of blocks creates a gap behind the board that reduces insulation value by 10-15%, it went on to state a 15-25mm gap caused by poor construction from cement snots would be a reduction of up to 40%.