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Insulating an on-grade floor

markgodfrey | Posted in General Questions on

I am planning a shop building in Ontario… I want it to be as energy efficient as is economical… for walls I will probably do a double stud construction with Roxul insulation and most likely similar for the roof… the floor will be on grade and I would appreciate suggestions for construction… I need a level floor capable of supporting woodworking machines, the usual- table saw, bandsaw, jointer, workbench,etc. all of medium size… concrete is possible but hard on the legs, wood is good if it can be made to stand up in an on grade installation…also what is best way to insulate floor and avoid moisture from below… I would also like suggestions for foundation other than concrete…

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  1. GBA Editor
    Martin Holladay | | #1

    The vast majority of builders would advise you to install a concrete slab. In your climate zone, the slab should be insulated, of course. You'll need vertical insulation at the slab perimeter, as well as a continuous horizontal layer of rigid foam under the slab.

    If you are worried that the concrete is too hard to walk on, you can install almost any kind of finish flooring you want once the slab has cured. If you are installing a table saw, bandsaw, jointer, etc., that means that the entire floor doesn't need to be resilient -- just some areas. Perhaps you can install rectangular strips of resilient rubber flooring to cover certain areas, where you expect to stand and walk.

  2. markgodfrey | | #2

    Martin, Is there an alternative to foam for under slab of the Roxul products for instance?

  3. GBA Editor
    Martin Holladay | | #3

    Yes. This article gives you lots of information: Sub-Slab Mineral Wool.

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