Part I – Wood Subfloor Specifications
- Subfloor panels should conform to US Voluntary Product Standard PS1-95, Construction and Industrial Plywood and/or US Voluntary PS2-04 and/or Canadian performance standard CAN/CSA 0325.0-92 Construction Sheathing. Other CSA standards also apply.
- Solid-board subflooring should be ¾” x 5 ½” (1” x 6” nominal), Group 1 dense softwoods, No. 2 Common, kiln-dried to less than 15 percent moisture content.
- Both CD EXPOSURE 1 plywood and OSB Exposure 1 subfloor panels are appropriate subflooring materials, but the proper thickness of the material will be determined by the factors noted below in Part IV – Panel Products Subflooring, E – Acceptable Panel Subfloors.
- Particle board is NOT recommended by Wego International Floors.
Part II – Subfloor Moisture
Note: The National Association of Home Builders' Green Home Building Guidelines contains the following directive under Section 5.3.8: “NAB Model Green Home Building Guidelines: Check moisture content of wood flooring before enclosing on both sides. Ensure moisture content of subfloor/substrate meets the appropriate industry standard for the finish flooring material to be installed.”
- For solid strip flooring (less than 3” wide), there should be no more than 4 percent moisture content difference between properly acclimated wood flooring and subflooring materials.
- For wide-width solid flooring (3” or wider), there should be no more than 2 percent difference in moisture content between properly acclimated wood flooring and subflooring materials.
Part III – Subfloor Flatness and Integrity
- Wood subfloors must be flat, clean, dry, structurally sound, free of squeaks and free of protruding fasteners.
- For installations using mechanical fasteners of 1 ½” and longer, the subfloor should be flat to within ¼” in 10 feet, or 3/16” in 6 feet.
- For glue-down installations and installations using mechanical fasteners of less than1 ½”, the subfloor should be flat to within 3/16” in 10 feet or 1/8” in 6 feet.
- If peaks or valleys in the subfloor exceed the tolerances specified above, sand down the high spots and fill the low spots with a leveling compound or other material approved for use under wood flooring. However, it is the builder's or general contractor's responsibility to provide the wood-flooring contractor with a subfloor that is within the tolerances listed above.
- Inspect the subfloor carefully. If there is movement or squeaks in the subfloor, refasten the subfloor to the joists in problem areas.
- Protruding fasteners are easily remedied by driving those fasteners deeper into the subfloor.
Part IV – Panel Products Subflooring
- For panel products subflooring, check for loose panels and re-nail or screw down loose panels securely.
- Ensure that there is proper expansion space (1/8”) between the panels. If the subfloor panels are not tongue-and-groov ed and if there is no sufficient expansion space, use a circular saw to create the specified space. DO not saw through joints on T&G subfloors.
- Also check for delaminated or damaged areas and repair those areas as needed.
- Make sure the subfloor is free of debris before beginning installation.
- Acceptable Panel Subfloors: Truss/joist spacing will determine the minimum acceptable thickness of the panel subflooring.
- On truss/joist spacing of 16” (406mm) o/c or less, the industry standard for single- panel subflooring is nominal 5/8” (19/32”, 15.1 mm) CD Exposure 1 Plywood subfloor panels ( CD Exposure 1) or 23/32” OSB Exposure 1 subfloor panels, 4' x 8' sheets.
- On truss/joist spacing of more than 16”, up to 19.2” (488mm ) o/c, the standard is nominal ¾” (23/32”, 18.3mm) T&G CD EXPOSURE 1 Plywood subfloor panels, (Exposure 1), 4' x 8' sheets, glued and mechanically fastened, or nominal ¾” 23/32”, 18.3mm) OSB Exposure 1 Plywood subfloor panels, (Exposure 1), 4' x 8' sheets, glued and mechanically fastened.
- Truss/joist systems spaced over more than 19.2” (488mm) o/c up to a maximum of 24” (610mm) require nominal 7/8” T&G CD EXPOSURE 1 Plywood subfloor panels, (Exposure 1), 4' x 8' sheets, glued and mechanically fastened, or nominal 1” OSB Exposure 1 subfloor panels, 4' x 8' sheets, glued and mechanically fastened – or two layers of subflooring. Or brace between truss/joists in accordance with the truss/joist manufacturer's recommendations and with local building codes. Some truss/joist systems cannot be cross-braced and still maintain stability.
- For double-layer subfloors, the first layer should consist of nominal ¾” (23/32”, 18.3mm) CD Exposure 1 Plywood subfloor panels (CDX), 4' x 8' sheets or nominal ¾” (23/32”, 18.3mm) OSB Exposure 1 subfloor panels, 4' x 8' sheets. The second layer should consist or nominal ½” (15/32”, 11.9mm) CD EXPOSURE 1 plywood subfloor panels, (Exposure 1) 4' x 8' sheets. The ½” plywood should be offset by ½ panel in each direction to the existing subflooring. The panels may also be laid on a diagonal or perpendicular, with 1/8” spacing between sheets. Nail on a 12” minimum grid pattern, using a ring-shanked nails or staples.
- Fastening and Spacing Specifications
- Follow the panel manufacturer's recommendations for spacing and fastening.
- Typical panel spacing and fastening requirements for truss/joist systems call for approximately 1/8” (3.2mm) expansion space around the perimeter of each panel, with panels fastened every 12” (305mm) along intermediate supports.
- Edge swell should also be flattened. This can usually be accom plished by using an edger sander.
Part V – Solid Board Subflooring
Solid board subflooring should be: ¾” x 5 ½” (1 x 6 nominal), Group 1 dense softwoods (SYP, Doug Fir, Larch, etc.), No. 2 common, kiln-dried to less than 15% MC.
Solid-board subflooring should consist of boards no wider than 6 inches, installed on a 45 degree angle, with all board ends full bearing on the joists and fastened with minimum 8d rosin-coated or ring-shanked nails, or equivalent.
Some types of wood flooring should not be installed directly over solid-board subflooring.
Thin-classification solid strip flooring must have a 3/8” or better plywood underlayment installed over solid board subflooring.
INSTALLATION OVER EXIST ING FLOORS
Wego does not recommend their flooring to be installed over existing floors.