Insulation under slab

[Sedgehammer]

I know this was discussed a bit in the sand or rock under the slab, but this is just about this.

I can get locally 3" Type ll EPS for $28.80 per sheet. That's $1,670 for the 58

I can get 2nds 1" XPS for $11 per sheet, so need 116 x $11 = $1,276. $400 difference. The XPS is in Indiana. 13 hours away. Which way do you swing?

Thanks

[alan gage]

If you don't have a preference between EPS and XPS then it seems like a no brainer. No way would I drive 26 hours to save $400. Fuel costs, meals, and value of my time would more than eat that up.

If you're thinking maybe you'd rather have XPS than EPS then I'd want to know how much it would cost to buy the XPS locally rather than taking the long drive.

But if it was me I'd probably get the Type II EPS if it was available locally no matter what.

Alan

[Sedgehammer]

@alan gage i agree on cost based, but wanted inputs on the type 2 eps being good enough

Is this good enough? it's 10 psi rated

R-8 Laminated Expanded Polystyrene Foam Board Insulation

[alan gage]

I really can't say because I've never used type II but at 20psi I'd think it would be fine. Have you calculated how heavy your slab will be?

Here's someone who wanted to know the same thing and the answers they got: EPS foam density for use under concrete slabs and around stem wall - GreenBuildingAdvisor

Alan