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Subfloors & Underlayments
- Above/Suspended – A suspended floor is one with a minimum of 18″ of well-ventilated air space below.
- On grade – An on-grade floor is in direct contact with ground or over a fill in direct contact with ground.
- Below grade – A below-grade floor is partially or completely below the surrounding grade level in direct contact with the ground or over a fill in direct contact with the ground.
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