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First off, I have 3/4 inch of this subfloor: enter image description here

It is on the first floor, and the area covers 700 sqft.

Question 1: What type of subfloor is this? I think it's OSB but I want to make sure because when I google particle board subfloor it looks like this in some pictures.

I got a measure from home depot. They said that I need 3/8 inch wood underlayment before I can install 1/2 inch solid bamboo flooring and that it would have to be glue-down.

The glue-down installation is 2.99/sqft plus $1.20 / sqft for the glue. The 3/8 inch wood underlayment is $1.56/sqft. Thats $5.75/sqft just for installation

It seems to me I should rather invest in real 3/4 inch solid hardwood and go with the nail down install $1.99/sqft, or go with engineered click bamboo and have it floated. (stranded bamboo cant be easily refinished so having solid vs engineered isnt a big deal)

Question 2: will I need a wood underlayment no matter what hardwood I choose and no matter what installation is used (float, glue, nail)? ( I know it depends on what manufacture recommends but in general)

  • I have regular plywood subfloor rather than your OSB subfloor, but the only underlayment my strand-woven bamboo (9/16 inch from Home Depot) required was the paper-tar-paper "Aquabar B". I'd avoid glue because it's unforgiving if you make any mistakes; I bought a 18 gauge nailgun and a compressor to do the install. I'd recommend screwing your subfloor down to the joists to reduce squeaking; I forgot to do that on the bottom half of my stairs, and two of the steps usually squeak. – Steve Nov 16 '17 at 23:14
  • A caution about the strand bamboo is that it really doesn't like water. About a hundred square feet of mine are cupped because a tub drain pipe came loose. You might want to get a preventive maintenance check-up on your plumbing before installing it. Another caution is that although it takes a lot to dent the stuff, it still scratches like regular wood. It's easy to hide scratches with oil (and probably wax, though I haven't tried that yet), but actually repairing scratches is a major undertaking. – Steve Nov 16 '17 at 23:17
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  1. Yes, that's OSB. It's the only product that's made with large wood "strands". I wouldn't have guessed that it was 3/4" though due to the apparent lack of tongue and groove along the longitudinal edge, but maybe the photo is misleading.

    Particle board looks like compacted pine sawdust. Fiberboard (MDF) looks like pressed pulverized wheat chaff. Neither of those are used as subfloor.

  2. No, not all wood flooring requires underlayment. Modern t&g subfloor in the 3/4" class is adequate for some products. However, a second layer can result in a stouter, quieter finished floor which feels higher quality. Read the label.

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The 3/4" will work over your existing subfloor. OSB during construction will swell at the edges from wet weather, and needs to be flattened out with a belt sander where and if it occurred.

I had a breakfast room in my place laid in 5/8" X 3 3/4" horizontal solid bamboo. I wanted to add onto it to go into the family room since it was in same "great room". I pulled up enough to tie into, the original lay was stapled down with 1/2" crown staples 2" long, I did the same with the new. Worked out great.

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