Underlayment

[gsmittle]

I'm about to put down 1/4" ply as an underlayment under hardwood floor in my LR. It will raise the hardwood to the same level as the kitchen floor we did a couple of years ago.

What does the group wisdom think: screw it down or use construction adhesive? The flooring itself is 3/4" oak nailed to the subfloor, with roofing felt under the oak.

g.

[JimD]

What is your subfloor? You probably know this and you mention height as the issue but the oak can be nailed directly to 3/4 plywood or OSB. If the sub-floor is particle board, you have an issue regardless of the 1/4. But assuming the sub-floor is OK, it probably doesn't matter. You will have a thousands of fasteners through the oak, 1/4 and into the subfloor. The quantity you put on the 1/4 to keep it in place before the oak is nailed down doesn't seem all that significant. I'd probably use construction adhesive and a minimal quantity of staples in the 1/4 to hold it in place and then start nailing the oak. I'm using red rosin paper under the oak I'm putting in now. I think it is equally acceptable and less messy than 15 lb felt.

Jim

[cabinetman]

I would screw down the ¼" if the floor under the ¼" is wood.

.

[gsmittle]

Thanks, guys. I hadn't thought to mention the subfloor. It's 3/4" ply, so no issues with the nails holding. I'll look at the rosin paper, too.

g.

[cwsmith]

I've seen nails, staples, and screws all used on different floors. Personally, the only way I'd go would be screws. Not quit as fast as staples, but it's pretty quick none-the-less.

I'm not a big fan of adhesives for jobs like this. To me, that says that you're never intending to ever change the floor again.. or have anybody else do it either. Adhesives just present a mess for someone in the future to have to contend with.

The red-rozen paper under your hardwood will keep most squeakes away. That is what our flooring expert used throughout the house.

When I bought this old 1887-built home about seven years ago, one of the previous owners used adhesives to apply the sub-floor and also to stick the red oak wainscote to the kitchen walls. It was a nightmare and took days longer than it would have otherwise.

I hope this helps,

CWS

[JSUPreston]

I would screw down the ¼" if the floor under the ¼" is wood.

I agree with this and some of the others. You don't want to use adhesive unless you absolutely have to.

[os1kne]

I agree with this and some of the others. You don't want to use adhesive unless you absolutely have to.

+1. Screws are the best way IMO.

[pelligrini]

Is there a living space under that room? If so, I would consider using a sound mat or one of the cork underlayment products. Although, shooting nails or staples through a sound product does decrease the benefits you can get on your STC and IIC ratings.

[gsmittle]

Flooring in Progress…

I ended up stapling down the 1/4" ply (no adhesive), then roofing felt over that (had a roll left over from another project, so it was cheaper than rosin paper). The flooring itself is 3/4" solid oak tongue and groove, nailed down with 2" flooring nails.

No living space under the room, just storage.

So far it looks pretty good, but still a long way to go.

Thanks to all for the suggestions/advice.

g.

[All Thumbs]

Staples was the right way to go, IMNSHO. 1/4" thick material isn't ideal for screws, have to screw-around too much with whether you get them sunk far enough, or too far.

[cabinetman]

Staples was the right way to go, IMNSHO. 1/4" thick material isn't ideal for screws, have to screw-around too much with whether you get them sunk far enough, or too far.

I would be reluctant to use staples, they could pull out. One inch coarse thread screws set just below the surface with clutched setting would be ideal, IMO.

.

[gsmittle]

I would be reluctant to use staples, they could pull out. One inch coarse thread screws set just below the surface with clutched setting would be ideal, IMO.

.

I'm not too worried about the staples pulling out, since there's 3/4" oak on top of it secured with a bajillion 2" flooring nails. If the staples pull out, I have bigger problems to worry about, like not having a floor at all. Gotta love living in tornado country!

g.

[Helicon1]

I'm considering doing the same thing. Adding 1/4 ply on top of 5/8 osb to raise the height of the floor to meet a new tile install in the kitchen rather than use transition strips. Finish floor will be 3/4 hardwood.

I think I am going to screw it down though. I'm not concerned about the staples pulling out, I'm concerned about them squeaking over time. I just pulled hundreds of them out of the new kitchen subfloor to prep it for new 3/8 ply and they didn't seem to be that secure.

Thoughts? Again it will just be to raise the height, not for strength. If the tile came out 3/4 high I would just lay the hardwood on the OSB.

[BigguyZ]

I would go with BOTH glue and screws. If you do it, I say do it right and make sure it's solid. I added 1/4" ply to an old 3/4" plank subfloor, and tiled over that. The subfloor obviously wasn't solid enough, and the grout lines cracked and a tile split. Do both and don't worry about it not being stable enough.

[cwsmith]

But "tile" is significantly different than a hardwood installation, as you have found out.

I really don't like glue for the pre-stated reasons (earlier post on this thread).

I guess staples, in conjunction with longer flooring nails would be sufficient. I do think that much of your installation would be the condition of the subfloor as it presently exists. For example, if it was 3/4 or better plywood already, then I think the addition of 1/4-inch underlayment really is only necessary to raise that floor to the kitchen level (as mentioned). My opinion is that unless the existing plywood is not in good, smooth condition the addition of underlayment does little.

However, if you are faced with old-style 3/4-inch boards (as in my 1887 house), then 1/4-inch underlayment would only slightly smooth out the possible uneven surface presented by any variation in thickness or cupping of the old boards. A thicker underlayment would be better.

BUT, when laying down something like ceramic or stone tiles you are faced with the problem of the subfloor flexing or moving under both the weight of the furniture, possible movement as the seasons change, and of course traffic. The tile itself will not flex and therefore if the subfloor is not absolutely stable, you will get fracturing at both the grouted seams and even cracking of the tile itself.

At my last residence, I remodeled the attached garage, changing it to a family room. The new floor consisted of 1 x 10 joists properly shimmed and leveled against the existing concrete floor and cross membered. I used 3/4 T&G good quality plywood which was screwed to those joists.

We had that area carpeted and we've had no problems whatsoever. BUT, when I thought about tiling the entry way, the installer would not do it... as in his experience that floor wasn't stable enough and he felt that the ply itself needed to be at least an inch thick, and better if possible.

That is my experience anyway,

CWS