General Sub Floor Requirements:
The sub floor surface must be flat. Flat means no low spots or ridges more than allowed by the manufactures instructions.
The sub floor must be structurally sound and clean of debris.
The sub floor must be dry. (See specific requirements for wood and concrete below)
Patching compounds must be allowed to dry thoroughly before proceeding with the installation.
Laminate flooring can be installed above, on or below grade.
Do not install laminate flooring in rooms with a sump pump or floor drain.
All sub floors must be checked for moisture. (See section on Moisture Testing)

Concrete sub floors
New concrete must cure for at least 60 days.
All slabs must be flat to within manufacturer’s recommendations.
Cover all concrete sub floors with a manufacturers approved vapor retarder.
Overlap all joints 8” and install from wall to wall.
Slabs on, above, or below grade, and lightweight concrete need a vapor retarder.
Existing sheet vinyl, VCT, LVT, ceramic tile, and terrazzo installed over concrete require a vapor retarder and must met flatness requirements.
Any existing wood flooring glued to concrete must be removed prior to laminate installation.
Carpet and pad must always be removed prior to laminate installation.
Any floating floors must be removed.

Wood sub floors
Wooden sub floors must be constructed according to local building codes, be structurally sound and deflection free.
Repair any squeaky floor prior to installation.
Sand or plane high spots.
Fill all low spots with Portland cement based patching compound.
Floor patch applied according to the manufacturer’s recommendations is a good choice to fill low spots.
It is not necessary to use a vapor retarder on top of a wooden sub floor.
Wooden sub floors constructed over a crawl space must have adequate ventilation, 1.5 sq. ft. per 100 sq. ft. of floor space.
The ground or concrete must be covered with a manufacturers approved vapor retarder to prevent damage due to excessive water vapor emissions. Overlap joints 8” and cover the entire crawlspace.
Basement walls and floors must be dry to prevent damage due to excessive water vapor emissions into the wooden sub floor overhead.
The moisture content of a wood sub floor must not exceed manufacturer’s recommendations.

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