Does insulation board in place of cavity closers meet building regs?

[r_c]

The spec for our extension states "All cavities to be closed with Termabate or similar" and the builder tried to tell us that the Celotex he used (see photo) was good enough. We argued quite a bit over whether he is following the spec, and he tried to tell us the old this is how it used to be done line.

But, he also claimed to have shown this to the building inspector from the council and apparently the building inspector was happy with it.

Does this satisfy building regs?

2016-07-21 20.18.50

• r_c
• 20 Nov 2016

 

[noseall]

Yes. I prefer to make my own and foam them in. Proprietary cav clodgers can be shoite.
The foil is meant to go against the masonry with a sleeve of DPC sandwiched between the insulation and the outer leaf.

 

[Nakajo]

It may be an opportune moment to advise your builder that deductions will be made for unapproved deviations from the spec.

 

[noseall]

It may be an opportune moment to advise your builder that deductions will be made for unapproved deviations from the spec.

Wait until he's submitted his extras bill first.

 

[^woody^]

It may be an opportune moment to advise your builder that deductions will be made for unapproved deviations from the spec.

"All cavities to be closed with Termabate or similar"

 

[Ian H]

Mine are like that but the foil is the opposite way

 

[Nakajo]

Yes. "Similar" is disastrous. I prefer "equal and approved".

 

[noseall]

A cavity closer is an uncomplicated bit of insulation with DPC stuck to it. Easy to replicate and improve (fixing wise) upon.

 

[r_c]

Nice photo 1990, which matches with what noseall said about the foil being against the leaf. Thank you all for your comments.

"equal and approved"

Much better worded

 

[whereistheundo]

@noseall I have a load of windows and a double door to close cavity on and am going to use the celotex DPC method but I'm confused as to how the sandwiching should work exactly. So DPC on outer membrane (100mm?) wrapped around celotex with foil facing internal/external bricks. Should the DPC be stuck to the outer wall (and if so is this a waterproof no more nails job or waterproof spray foam?). Should DPC run in between celotex and inner wall insulation?

If you could show a diagram it would be much appreciated. I only want to do this once obviously. This is all completely new stuff to me.

I'm happy to share a pic of the setup - we have a 150mm cavity (ish). 100mm celotex attached to inner wall. windows have already been installed, so this method seems like the most do-able. Fingers crossed.

Thanks for reading.