Concrete slab insulation

Pygmie

We are extending our kitchen and the builder has excavated the additional floor space outside. He mentioned that they plan on putting 100mm of polystyrene as insulation. Can anyone tell us if this is enough by today's standards? Thanks in advance!

893bet

Not even close!

e.r

Cheapest form of insulation
some kingspan should have better thermal value

Pygmie

Thanks for that. Looking at the kingspan it states that 100mm is equivalent to an A3 rating. I wonder is it worth putting that much in if the existing kitchen floor, which was laid 14 years ago, probably has less insulation?

BryanF

e.r wrote: »

Cheapest form of insulation
some kingspan should have better thermal value

Nothing wrong with polystyrene, you just need more of it than PIR

Passive standard would require min 200

Pygmie wrote: »

Thanks for that. Looking at the kingspan it states that 100mm is equivalent to an A3 rating. I wonder is it worth putting that much in if the existing kitchen floor, which was laid 14 years ago, probably has less insulation?

There are min building regs here you must comply with them http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,27316,en.pdf

If you can't decipher them, then you need to hire someone who can, typically an arch / eng

Pygmie

Thanks for that. I'm reading that you need 30% more polystyrene to match the same thickness of PIR. I haven't seen this in an official document though. Can anyone confirm? Thanks again!!

cork2

Surely whatever professional does the drawings for the extension, can do the calculations and advise you the best materials to use.

BryanF

It was the same with the radon.

Pygmie

We have hired an engineer to do the drawings. So it's ok to expect him to advise on insulation too?

Pygmie

Sorry if I'm coming across dim. This is the first time doing anything like this.

cork2

If your engineer is designing and signing off on this extension then it's his job to specify all things such as insulation, ventilation, foundations, blockwork, steel and make sure the work is carried out in accordance with the building regulations in general.