Plywood versus Advantech - hey builder/contractor guys...

[turbo6bar]

I am rebuilding a 60 year old house and need to decide whether to stick with old school t&g plywood or use the newer Advantech enhanced OSB for the subfloor. This will go over 1x6 decking that is currently nailed to the joists. The house does have a few water leaks due to improper roof flashing. However, these issues will be fixed as soon as possible.

I planned to use t&g plywood. The rep at one lumberyard says I can use either plywood or advantech (or even the cheaper LP product). Sales guy from other yard strongly recommends Advantech.

I am looking for a stable, durable subfloor. Finished floor will be hardwood and tile.

Also, what do you guys recommend for fastening? I was planning to use subfloor adhesive and 2 3/8" nails into the floor joists. Other option is drive screws or follow the nails with screws. Since the floor joists and decking are not flat (1/16"-3/32" variance in decking thickness), I'm concerned the screws might make the sheathing dip in the low spots, whereas nails will allow the sheathing to float the low spots with adhesive bridging the gap.

I've found that using nails to fasten tile hardieboard allows the board to float on the thinset. When I've used screws, the finished surface isn't nearly as flat. I figure this theory might apply with the subfloor.

BTW, the Advantech is around $19/sheet vs 3/4" plywood at $22/sheet, so price isn't an issue.

???
Jurgen

[look 171]

What kind of finish floor is going on top? I like plywood. Have not been a big fan of OSB. Screw for added insurance. You really need to screw it down if its going on top of another sub floor. Why do you think you need another sub sub-floor on top of another?

[trekkor]

3/4" plywood. Screwed, stapled and glued.
T&G not needed.


KT

[trekkor]

Consider planing the high spots on the floor first.


KT

[RWebb]

I took a gf to see a local builder's model house display a few years ago -- the "Street of [Wet] Dreams." Big fancy, Calif. style McMansions, and they were ALL made with OSB!!

As we were leaving, I happened to notice a big sign advertising the Contractor -- yes, you guessed it -- the sign was made from plywood. The Builder can pretty much wash his hands of the houses after 1 year, maybe 2. But he wants that sign to last.

[onewhippedpuppy]

I helped build a house with Advantech, if you need t&g it is superior. Go look at a stack of CDX plywood at your local lumberyard, try to find a flat sheet. Then imagine how much fun it will be to line up two warped sheets of plywood. Advantech is nice and flat. If you buy the gold edge like we used, it is also water resistant.

You can screw or nail, just use the glue. Using a nailgun will greatly speed the install.

[turbo6bar]

Originally Posted by look 171

What kind of finish floor is going on top? I like plywood. Have not been a big fan of OSB. Screw for added insurance. You really need to screw it down if its going on top of another sub floor. Why do you think you need another sub sub-floor on top of another?

3/4" solid hardwood (not prefinished) in most of the house. Mud bed and tile in the bathrooms.

Reason I'm considering going on top of the 1x6 decking is because the floors are bouncy (like when a person walks across the room). Originally, the house had 2 1/4" oak hardwood nailed to the decking. It was in horrible shape and had to be removed. The bouncing wasn't readily apparent when the hardwood was down. Now, it's pretty bad. My plan was to install the plywood, and then sister joists if the floor was still bouncy. Then, I'd have hardwood on top of 3/4" decking and 3/4" plywood.

The other issue is some joist spans are really pushing it (14' span on 2x8 joists @ 16in on center). It might be better to spend time adding a sub girder on the long spans and drop the extra layer of t&g.

Main thing is I don't want to do this over again. Gonna talk this one over with the framing carpenter once again and formulate a plan. I'd hate to spend time and money throwing down sheathing and find I should have spent the time adding piers and girders to stiffen the floor framing.

trekkor, why not use t&g? Much easier to install?

matt, the contractors on various forums rave about advantech, but most of the praise is over the ability for the product to get wet and not swell. I think plywood is a bit stronger, though.
jurgen

[TimT]

Reason I'm considering going on top of the 1x6 decking is because the floors are bouncy (like when a person walks across the room).

...snip.....>


The other issue is some joist spans are really pushing it (14' span on 2x8 joists @ 16in on center). It might be better to spend time adding a sub girder on the long spans and drop the extra layer of t&g.

Install more blocking, or somehow improve the stiffness of the joists. Adding additional dead-load will not help, and will only hurt the amount the joists deflect..

[Zeke]

Trekkor said T&G not necessary because you're going over another floor.

I don't see where you will get a "float' just because you use nails instead of screws.

[turbo6bar]

Thanks for the insight. Thinking about several ways to stiffen these floors. It just takes some materials and sweat equity.

[dipso]

I just re did the underlayment in our kitchen. We are in the beginning stages of a kitchen remodel.
I used OSB and screws. Solid as a rock.

I think it is about 2 ft spacing on the floor joists, 1"x6"s on top of that and then the osb on top. It's nice.

All I did was the OSB. The other stuff was existing.
I could take a picture if you like.
There is still no floor or cabinets.

[onewhippedpuppy]

If you need additional stiffness, they make Advantech in 7/8.

[trekkor]

3/4" ply wood over the existing subfloor will be suitable for any finished floor.
Screw down the existing subfloor first. ( minimize future squeaks )

Tell us the distance between floor joists.




KT

[A930Rocket]

3/4 " Advantech for the win. As noted, screw the 2x down and then screw down the Advantech after glue/nailing in place.

[dipso]

I screwed down my underlayment, through the subfloor into the joists. Thats what you should do.
Mine are 16 on center. Just looked.

Even though OSB is glued together I still didn't trust it against water. I put the wax side down, so any moisture from under the house won't get at the wood. It says wax side up.
Then I am going to seal the top side before I put the floor down.

I think the OSB is better than plywood. Plywood has pockets and not as much glue.

[look 171]

Blocking it off will help a lot. I would add the girder, and block it off. That's a no brainer. Finish it off with 5/8" plywood and some screw. Not drywall screws. Once finished, it will be a really tight and strong floor. Mud bed will take care of all of the dips and high spots. You can get anal and shim all the high spots on the sub floor and screw it down before the plywood. This is the hard wood floor area. We did that on the Greene and Greene restore. It was a bit of a pain in the rear, but necessary due to the big money they were spending.

Do the different finish floor meet somewhere? Are you concern about the two area beign different height. Now is the time to make the adjustment with the different thickness plywood sub floor.

To answer your original question, plywood should be more then fine.

jeff

[turbo6bar]

Many thanks, guys.

dipso, I'm hesitant to use regular OSB because some folks warn about installing hardwood over OSB. Some say you have to use staples to fasten the hardwood, and I only have a nailer. Plus, I want extra strength, and plywood wins that battle.

whipped, I also heard Advantech is available in 1 1/8". I'd get into transition height issues, then, though.

trekkor, all joists are on 16 centers. I definitely plan to stiffen the joists.

lookfan, there are two areas where the tile and hardwood will meet. One bathroom has been totally gutted (actually, entire house is down to rough framing). That bathroom floor was partially collapsed and patched, so we're rebuilding it, or rather, overbuilding it with 2x10s for the 8' span. We're going to recess new framing so the subfloor + mud bed + tile will be close subfloor + underlayment + hardwood.

Do you guys think the screwguns will collated screws are worth the premium? I'm still young and stupid and don't mind getting on my knees to drive screws, but time IS money.

BTW, I have been eyeing picture books about Greene and Greene homes. Going to use some architectural details to spice up this house.

I'll report back with results soon.
Jurgen

[island911]

Originally Posted by dipso

...
I think the OSB is better than plywood. Plywood has pockets and not as much glue.

:-/ that's not how it works.

Consider the flooring on airplanes (honeycomb panels.) The middle needs very little structure to hold the sheer/internal forces.

Personally, I choose plywood. --good plywood will out perform good OSB in just about every way. OSB might (slightly) win out in sound damping; as it will be less stiff.

[Talewinds]

Consider another factor from builder's perspectives. With a house under construction and installing the subfloors or roof sheeting, if using plywood and it gets a hard rain on it even once (the chances of this are better than 50/50 in the midwest summer) the surface will be damaged to the point that it will require replacing.
OSB on the other hand, can withstand several bouts of rain before the edges will begin to curl (this is further helped if contractor sweeps any standing water off the subfloor after the rain).
Nobody, NOBODY around here uses plywood for subfloors anymore, they haven't for years, even when plywood was less expensive.

Caveat: Regional differences apply, usually due to climate. The dry states still use a lot of plywood.