first, just wanna say thanks for sharing all the great info on the board. i've learned more here than i have trying to talk with local installers.

so here's the situation. my mom wanted to install wood in her familyroom which was carpeting. i pulled up the carpet. my plan was to run in a bunch of screws to make sure the subfloor was secure then sand all the seams to make sure they were flat. when i went to put the screws in i noticed the joists were not 16in....instead the subfloor is sitting on beams 4 ft apart. being that you can't feel the floor move, i'm thinking it must be 1.25 in plywood. so my question is this (well, i actually have 2). first, what should i do if anything about the joists? can i glue/screw another 1/2 or 3/4 sheet on top to make it 2 in thick? second, there is a fireplace that is kinda the focal point of the room. i'd like to run the strips parallel the the fireplace but that would mean they would be parallel to the beams too.

oh, if it matters....she's looking at prefinished wood strips...oh, and this will be my first wood floor.

thanks for any help/advise you guys can give. i'm really at a lost as to how to move ahead. oh, and just so you know....yes, i have asked local installers and they don't really want to offer advise. they all want to come out and give me an estimate.

can you access to the floor from underneeth? 4 ft span between joist wouldn't hold the plywood up, 24" centers are possible though. Pull up an air vent and try to see the actual thickness of the subfloor. about running the floor in the same direction of the floor joist I would say no if your floor joist are that far apart. picture frame the hearth first then use that as your starting point if at all possible.

From your description, it sounds like your subfloor is of an older design used during the 60's and 70's and, for a short while, in the early 80's. The design uses 1&1/8" T&G plywood subflooring spanned over 4x6 beams which are spaced 4' oc. The problems this subfloor system may have are dips (low spots) between the beam locations and a tendency to be bouncy. Also, the piers that support the beams have sometimes been known to move alot causing humps in the subflooring. So much so that in some subdivisions, metal jacks were used instead of 4x4 posts so one could re-level the floors. Needless to say, this system is no longer employed. But to your questions. With this type of subfloor, you will need to check for FLATNESS, especially between the beams. Sand high spots and fill in low spots. While that 1&1/8" plywood is thick enough, adding an additional layer of 1/2" will stiffen things up some more and reduce some of the bounce inherent in these floors. If yours doesn't seem bouncy, forget the 1/2". As for floor direction, with this system, you can run the hardwood flooring any direction you choose. You do not need to run it at 90 deg. to the beams

gary, you are correct...1&1/8 t&g, 4x6 beams, even the metal jacks. i'm thinking even though i can't feel the floor flex, i can't say for sure that it's not moving a little...and maybe enough that it may squeak when the wood is down. so i'm thinking it would be better to be safe and add the 1/2 in on top just to be sure. so, how would you recommend doing that? i was thinking a case of const adhesive and a bunch of screws....or adhesive and 10 million staples (which would be faster than screwing).

thanks!!!

oh, one more thing....sorry my 2 questions just turned into 20....but i'm learing a lot

should i try to do anything to level it before i put down the 1/2in or just do it after?

IMO, staples are best. IF the floor ever needed to be removed, the guy removing it would be cursing you over that glue and the screws. Staples work great. Use 15 gauge, 1/2" crown with 1&1/2" legs. Staple perimeter of 1/2 ply 4" oc and a grid 6" oc in the field. Staple ply starting from the center of the panel out to the edges to avoid lumps in the underlayment.

true about the glue....knowing my luck i would be the one removing it, thinking, "well, that was pretty stupid to glue it."

thanks a bunch. i feel much better now that i know what i need to do. guess i know what i'm doing next weekend...


thanks again!

You must FLATTEN that subfloor before installing the 1/2". Do NOT use floor filler, self leveler or any of that. Thats for glue down floors. You can use 30 lb. felt, asphalt roofing shingles, thick cardboard, thin plywood, etc. for filling in low spots THEN after that, install the 1/2" plywood. Much nicer and cleaner looking job.

cool...thanks. i think the felt should work good. i did a quick check last weekend and it wasn't too bad...just a few spots that will need some filling.

thanks for the education. you've been most helpful....