How to Prepare a Concrete Slab for Wood Flooring
A concrete slab can serve as an ideal support surface for wood flooring when properly prepared. As a strong and solid foundation, a concrete slab will give a wood floor a stable surface that protects the wood from the extreme effects of weather or from the subfloor settling over time. Does this Spark an idea?
Things You'll Need
- Broom
- Wire brush
- pH neutral cleanser
- Concrete degreaser
- Level bar
- Pen
- Concrete grinder
- Self-leveling compound
- Mortar
- Trowel
- Concrete joint repair
- Mastic
- Asphalt felt
- Plywood boards
- Nail gun
Instructions
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1
Clean the concrete slab thoroughly, removing all traces of dirt and debris using a broom and a wire brush, then wash the surface of the concrete with a pH neutral cleanser. Remove any grease from the floor using a concrete degreaser, and wash the solution away with water.
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2
Check the surface of the slab to determine if it's level. Drag a leveling bar (a long flat bar) across the surface of the slab, marking areas of the slab containing rises or dips by circling the areas with a pen. If the slab is not level, level it before you lay down the flooring.
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3
Level the slab by grinding down the high points using a concrete grinder. For dips in the slab shallower than 1/8 inch, fill the area with self-leveling compound, spreading it even with the surface of the slab with a trowel. For dips greater than 1/8 inch, fill the dips with concrete mortar, leveling the mortar with the trowel.
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Repair any cracks in the concrete by first cleaning out the cracks with a wire brush, then filling them with concrete joint repair.
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5
Allow the leveling and repair materials to dry overnight.
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Spread a level of asphalt mastic to the slab's surface using a notched trowel. Spread the mastic evenly using the flat side of the trowel, then hold the trowel at a 45-degree angle to raise a series of notched ridges in the mastic using the notched edge of the trowel. Spread the mastic in long rows, wide enough to create a backing for a row of asphalt felt.
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Allow the row of mastic to set for 30 minutes, then roll a layer of asphalt felt onto the mastic, butting the ends together while overlapping the edges of the felt four inches. The felt will serve as a moisture barrier between the slab and the wood flooring.
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Place a second layer of mastic on top of the felt.
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Lay plywood boards onto the mastic, securing the boards into place using a nail gun. The boards will create the final subfloor layer for the wood flooring. Lay the plywood so that it lies diagonally to the direction in which you intend to install the floorboards.
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