Question for the experts.

I have been researching the internet on installing hardwood on a slab in my home and have read posts on various flooring forums. Just trying to confirm a couple of things.

The flooring I chose is Somerset engineered 3 1/4" wide 1/2" thick. No moisture issues. I plan on laying 6 mil plastic then 2 layers of 3/8 " exterior plywood perpindicular to each other. Then rosin paper. Then install floor using a Bostitch EHF1838k18 gauge flooring stapler.

1. With the plywood, how much of a gap or space should I leave when laying the sheets down or can I but them up to each other ?

2. Should I glue and screw them together or maybe 5/8 staples to secure the 2 layers. Not sure what kind of glue .

3. There is an area where I need to reverse direction. Would a spline in the groove work ? Is that something that can usually be purchased or would I have to make one and is it glued or nailed in.

4. Do you have any opinion on Somerset flooring in general ?

5. Also I was going to purchase the stapler but before I do, do you think this is the right tool for the job. On the somerset web site it says use staples or cleats but doesn't say anything about the gauge of them.

I am sorry if that is a lot of questions. I am getting ready to tackle this and nobdy local seems to be knowledgable on this subject. From what I've read on this forums it sounds like some of you know your stuff. Any help would be greatly appreciated. Thank you.

Not sure why your even planning a floating subfloor with engineered. We usually only use that method for solid installs. Engineered is made for use on concrete.

Trying to keep the floor as low as possible due to some height issues with front door and a tiled bathroom floor. I know its only a 1/4" but it will make a difference and save me some work. Otherwise anything wrong with how I plan to do it.

I'm still not seeing it. Two layers of 3/8 = 3/4 of an inch, plus the 1/2 inch floor is 1 1/4 inch high. Your saying the tile is 1" high set to the slab? If you glued the engineered or just floated it over a cushion/vapor retarder(if manufacturer says is applicable) then your as low as you can get. Not sure what this 1/4 in difference your talking about.

Other than that gap the sheets at least 1/8in and 1/2 in around the perimeter. No glue necessary. Your fastener should not bottom out or you will puncture the 6mil. Plus for added insurance I always try and get the enduser to use a trowel on vapor retarder and the plastic when doing floating subfloors. Can't do it afterwards.

Kevin can probably help better than all of us as he is a Somerset dealer.

Aside of what else has been said, keep an eye on those door areas. In other words, check the entire area where the doors swing. Been there before where one high spot ruined a good day..after the ply was down

Spline. Unfortunately I rarely encountered engineered staple downs (all work in Florida) but it seems to me one would have to craft their own spline. I don't recall anyone ever offering such with engineered constructed hardwoods. I'm with floormeintucson...a bit lost on your description of height and reasons for doing so.

I rechecked and it looks like I am going to have to trim the bottom of the door anyway so I might as well use 3/4". I really dont want to do a glue down on the slab. I've seen 3/4" solid and 3/4" that looks like it has 3 layers. Is one better than the other? Also would 1.5" nails/cleats be the way to go?

Also with the 2 layers of 3/8" plywood, no need to glue the top layer to the first. Just secure it with screws or staples.

Thanks for the replys.

I'm really confused by this entire thread.

I agree, it would be foolish to add two layers of plywood underlayment to install engineered, unless there is so height you're trying to make up someplace with another floor.

Glue or float the stuff directly over the concrete and save the cost, headache and time!
It seems to me, You're over thinking this.