Insulated Slab on inside of External Walls

Cushtie · 17-07-2021 08:50AM #1

Hi,

Currently building new build. Our Engineer has specified 200mm pumped cavity on external walls. I was thinking I might also add an insulated Slab to the inside of the external walls. It's adding about 3k to price of build. Not a huge sum in the grand scheme of things. The builder although happy out to do it thinks its overkill, house will be too hot and no need for it. Any thoughts?

I just have this thing about putting in as much insulation as possible.

(House is A2 rating with Heatpump / UFH and MHRV)

Cheers.

Biker1 · 17-07-2021 09:44AM

https://boards.ie/discussion/2058199259/insulated-slab-on-inside-of-external-walls

Complete overkill. Extra insulation over the calculated optimal amount is a waste of money plus you lose the thermal mass of your external walls. You would be far better off ensuring an airtightness result of 1m3/hr/m2 at 50pa or better is achieved.

Yellow_Fern · 17-07-2021 02:11PM

In hot weather that exposed slab is awesome for keeping the house cool if it is wet plastered. Focus on hidden thermal bridges and airtightness

Yellow_Fern · 17-07-2021 02:11PM

Insulated Slab on inside of External Walls

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