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Is it correct to use OSB material as a partial base under kitchen counters with granite countertop?

phillipstoaster | Posted in General Questions on

Is it correct to use OSB material as a partial base under kitchen counters with granite countertop even if all base seams sealed with a suitable calking material?
Contractor wants to use OSB board to help as alignment base for kitchen counter cabinets. OSB board to be layed over older,15 year old, maghoney underlayment which is in good condition.

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  1. GBA Editor
    Martin Holladay | | #1

    Your question is confusing. Are you wondering whether OSB is needed for structural support? I'm not sure what the use of OSB under granite has to do with "base seams sealed with a suitable caulking material."

    First of all, what are "base seams"?

  2. wjrobinson | | #2

    OSB not the best to be near moisture. Caulk does little to hold out moisture over time. In fact caulk does a great job of holding in moisture that goes past it via capillary action.

    Luan is more forgiving and or floor leveler. I have never myself added OSB under a cabinet. But also most here know I have nothing good to say about OSB or even today's lowest cost plywood. The good stuff simply costs more.

  3. GBA Editor
    Martin Holladay | | #3

    Here are two articles on installing granite countertops:

    Granite Countertops

    Installing Stone Counters

    In both articles, the authors recommend setting the granite countertop directly on the cabinets, with only silicone caulk between the cabinets and the stone.

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