advice on subfloor materials and installation
Adding 200 sq ft to existing raised foundation house for kitchen/bath extension. Foundation is completed and so are 2×6 floor joists on overkill 12 inch centers. Ready to now install 3/4 in plywood subfloor and cover with Amtico vinyl flooring. I’m gutting the existing room next to this extension including ripping out existing subfloor, so I can replaceall with 3/4 thick plywood and keep a minimal height difference at entrance to new flooring system.
What kind of screws should I use to attach the 3/4 in plywood to the joists. The “GRK fastener”s #9 x2.5 in screws at Home Depot look pretty good. Plus will use either liquid nails or Loctite PL400 subfloor adhesive in addition to the screws. Is screwing every 6 inch overkill ? 12 inch ok ?
Leaning towards 3/4 non tounge and groove plywood simply because I cant find 3/4 TG, only 1 1/8. I have added 2×6 blocking along the edge of the 8 ft direction of the plywood for additional support. Thinking of making the blocking double wide so that two adjoining sheets each get 1.5 in of support. Plywood will be installed perpendicular to the floor joists.
What about the grade of the plywood ? One floor installer said use 23/32 CDX plywood ($19.97 per 4×8 sheet) and use a cementous levelling product on it to cover knot holes and voids. Another said to use 23/32 AC at a whopping $39.94 a sheet. So, is using the cheaper CDX ok with leveler so the surface imperfections will not show thru the Amtico vinyl strips.
The Amtico vinly looks like wood and is about 6 in wide by 36 in long.
thanks for your replies