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Community and Q&A

Slab insulation

RebeccaDorr | Posted in Green Products and Materials on

I am a green building novice looking for help on materials for a new garage. I have seen some information and posts about garages and concrete slab, but I’m having trouble pinpointing what I’m looking for. I live in Zone 4/5 Massachusetts. The garage will be for cars, a tractor, and storage for my husband’s tools. He’d like to have a concrete floor for many reasons, and while I resist concrete for its eco-footprint, I can’t seem to find an alternative with the same solid, firm surface as traditional concrete (this is not my main question, but I’m open to any innovative ideas that knowledgable folks have to say on alternatives, which I’ve read a lot about). The garage will not be heated, but it will be insulated eventually. Looking at some innovative wool and hemp products.

My main question is about insulation for the concrete slab, if we do indeed go for it. My contractor is planning an Alaskan slab, and he wants to insulate with foam board. I have said from the beginning that I would prefer not to use foam, but he still has it in the plans. I am averse to foam as a material on a number of levels and am looking for alternatives. Rigid rock wool Something else? So grateful for any advice.

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  1. Jon_R | | #1

    You could investigate scoria under the slab. But be careful you don't create something that sounds green but is actually less green than EPS.

  2. RebeccaDorr | | #2

    Yes, I understand. I'm particularly concerned about the fire retardants in the rigid foam and would prefer a product that didn't use them, but I don't want to use something that's not appropriate for the placement. I don't know much about rock wool and fire retardants, and I've read that they are energy intensive to produce. I'm curious about perlite and its applications with concrete, but I don't know if could be appropriate for this project. Still open to ideas!

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