Plywood spacing

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Screws are wrong for the application here, if using resilient. Use ring-shank nails or screw shank nails, no longer that the total of the two panel thickness- 1-1/4". Pull the screws, use them when you build a deck or install sub-floor. Don't angle nail, fill the end joints; http://www.norbord.com/na/cms/wp-content/uploads/L335M.pdf

Gary
 
I don't think it was that, I tried different sizes on a test spot of the bare subfloor planks, same result. Either way I used some liquid nails Subfloor, then laid the plywood and screwed, then in spots screws wouldn't countersink, used the nail gun to shoot in ringshanks. I was wondering if anyone puts silicone between the plywood/bathtub gap to help keep water out in case it ever leaks in there? Thanks for the help guys.
 
GBR said:
---Welcome to the forums!---------

Screws are wrong for the application here, if using resilient. Use ring-shank nails or screw shank nails, no longer that the total of the two panel thickness- 1-1/4". Pull the screws, use them when you build a deck or install sub-floor. Don't angle nail, fill the end joints; http://www.norbord.com/na/cms/wp-content/uploads/L335M.pdf

Gary
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I'm re thinking resiliant, ceramic tile might be the better long term option. Also why would it being screwed down matter besides being a huge pain if it ever gets ripped out. Like I said first time doing this and theres so many dif opinions on how to fasten in this situation.
 
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Screws may work, just not recommended by that (and other) plywood manufacturer. READ the finish floor manufacturer's recommendation on fasteners. The top layer (underlayment) needs to expand/contract with the seasonal RH, so the edges move slightly, as the linked pointed out-they need filling after they acclimate; just before final vinyl flooring. The screws should not be any longer than the two panel thicknesses as longer ones may pop due to depth through panel, again in article. The screw shank should not be threaded where buried in underlayment, only in sub-floor; Fig.7-16; https://books.google.com/books?id=L...thread length on decking screw better&f=false
Screws also tend to pucker the face grain, IME, and stand proud when sanding, especially at the joints when the fastener is so close to the edge a thinner nail works much better- staples- better yet. Use a vapor barrier to stop any moisture from the crawlspace or "exterior" grade of underlayment with resin glue (vapor barrier)

I use caulking at the tub to stop any moisture intake at the plywood end grain exposed there, with backer rod underneath. Using a hard putty there would not bond for long due to the two different materials rate of expansion/contraction; wood ply/steel-FG tub.
After you cut an underlayment/vinyl floor up into 2' squares, a 3' bar and a block with my size 10-1/2 boot lift it right up...lol.

Gary
 
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GBR said:
Screws may work, just not recommended by that (and other) plywood manufacturer. The top layer (underlayment) needs to expand/contract with the seasonal RH, so the edges move slightly, as the linked pointed out-they need filling after they acclimate; just before final vinyl flooring. The screws should not be any longer than the two panel thicknesses as longer ones may pop due to depth through panel, again in article. The screw shank should not be threaded where buried in underlayment, only in sub-floor; Fig.7-16; https://books.google.com/books?id=L...thread length on decking screw better&f=false
Screws also tend to pucker the face grain, IME, and stand proud when sanding, especially at the joints when the fastener is so close to the edge a thinner nail works much better- staples- better yet.

I use caulking at the tub to stop any moisture intake at the plywood end grain exposed there, with backer rod underneath. Using a hard putty there would not bond for long due to the two different materials rate of expansion/contraction; wood ply/steel-FG tub.
After you cut an underlayment/vinyl floor up into 2' squares, a 3' bar and a block with my size 10-1/2 boot lift it right up...lol.

Gary
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I decided to just go with ceramic tile when I do the floor. The deck screws I used had no threads at the top of the shank to the head. I used the right size for the thickness of the subfloor planks and the 1/2'' plywood. I'm going to use schluter ditra over this and then tile. I was going to get the screw shank nails and revive screws but since I'm ditching linoleum and going real role I should be fine. I just hope I'll never have to rip that floor up for any reason. Even in sections subfloor glue and screws might need replacing most the planks too haha.
 
I'm sure glad I happened to stumble upon this. I'm just about to lay down some plywood subfloor (to compensate for carpeted inserts in the existing laminate, over which I'm installing the new flooring), and it wouldn't have occurred to me that plywood would need expansion room between the sheets as well as at the walls. Thanks a lot!
 
zepper said:
I'm sure glad I happened to stumble upon this. I'm just about to lay down some plywood subfloor (to compensate for carpeted inserts in the existing laminate, over which I'm installing the new flooring), and it wouldn't have occurred to me that plywood would need expansion room between the sheets as well as at the walls. Thanks a lot!
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Take that with a pinch or salt. The rules for gapping are the same for new construction when wood is subject to rain for days before it drys out.

Engineered hardwood is plywood, we don't see gaps left between those board.:p
 
nealtw said:
Take that with a pinch or salt. The rules for gapping are the same for new construction when wood is subject to rain for days before it drys out.
Click to expand...

Maybe I'm not following you. You're saying that if you install plywood that's been rained on, you don't have to gap it because it'll shrink? That makes sense in a strange kind of way, but I'm surprised that anyone concerned about building integrity would install wet wood... Isn't that just asking for trouble?

nealtw said:
Engineered hardwood is plywood, we don't see gaps left between those board.:p
Click to expand...

True, but you can't leave gaps between hardwood boards; it's not an option. Otherwise it might not be a bad idea!

The plywood's covered, so assuming it's properly screwed down, there doesn't seem to be any reason not to leave 1/8" gaps between sheets. That small a gap won't affect the floor's integrity. It's just a bit of insurance.

How much can plywood expand? After all, it's designed not to change, right? I looked around a bit and I found this on the site of the Ceramic Tile Institute of America (CTIOA):

The several layers of wood that go to make up a sheet of plywood are placed so that the grain, of individual layers is opposite that of the preceding layer. However, the least amount of shrinkage will take place parallel with the face sheet grain. A typical sheet of Douglas Fir plywood unrestrained will expand and contract 7/32" over its length and over 3/32" on its width. The amount of expansion and contraction will also depend on how securely the sheet of plywood is restrained nailed or otherwise fastened.
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(I assume that applies no matter what you happen to be installing over the plywood.)
 
You live in Van. so you know the rain we can get, we install dry plywood, floor and roof and it gets wet, believe me we do not worry all that much about the spacing as that would require cutting that bit off every sheet.
With all that rain, never seen that kind off expansion. If your plywood patch is attached to plywood sub floor below they should move as one
And yes leaving a space would not hurt anything.
 
You gap all plywood (unless acclimated)/OSB. Exterior is 1/8" and interior (underlayment) is only 1/32" as per article. This is to allow for expansion of the product to acclimate during the time it takes you to install resilient over it. Screws in underlayment over another sub floor plywood are not recommended because they could pull out with a thin product below. It sits on the one below, not secured so tightly that it won't also flex when load is applied at joist mid-span. The top layer acts slightly independent of the bottom layer- hence not fastening into the joists. Being different thicknesses- different amounts of flex- unless you used construction adhesives.

I hope all read the manufacturers recommendations on any plywood product before install...

"You live in Van. so you know the rain we can get, we install dry plywood, floor and roof and it gets wet, believe me we do not worry all that much about the spacing as that would require cutting that bit off every sheet."--------- you probably have not had trouble with buckling of sheathing because the plywood has already been acclimated, either stored outside at the lumber yard or at the job site. Wouldn't you just allow for the gap when spacing the sheets, all-important when using OSB; http://www.norbord.com/na/cms/wp-content/uploads/Correct-Panel-Spacing.pdf

http://www.apawood.org/buildertips/pages/M300.html

"if the panels were not acclimated before installation, a 1/8-inch gap at edges and ends."---------- https://www.google.com/url?sa=t&rct...d=9633&usg=AFQjCNEhsxiIewaIfbu_3NK_J7nqyonwRw

Gary
PS. I wouldn't compare a 4-6" wide plywood plank to a 4x8' panel and expect the same expansion, only after acclimation.
 
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My 1/2'' plywood was acclimated before I fastened it to the 3/4'' subfloor. I didn't gap it The tile guys said it will be fine they haven't had a problem, but the Schluter Ditra membrane I'm going to use calls for 1/8'' gap so I'll just run my circular saw down the joint to get the gap. Problem solved.
 
Estpaul said:
Thanks fire the help. Plywood is fastened down and was a pain in the ***. Some screws just wouldn't countersink and just spun. Even in the areas I replaced broken planks so some spots I just had to keep drilling till one grabbed and countersunk.

There may be several reasons for screws not holding, e.g. spinning when they are driven in, and not "self countersinking.. the thread is stripped.. which may be for a few reasons.. overtorqueing for the wood which may be aggravated by too large a pilot hole, or (dry) rotten wood in the sub floor. So try this. Drill a smaller pilot and mostly just in the plywood, drill slowly into an already countersunk hole to just before flush. Finish just by hand. Does it spin?

Jam a sharp point awl into several places in the subfloor planks. Does it go in "easily" about a half inch to an inch? Rot.
Click to expand...
 
Floor is fastened now. Used ring shank nails in spots screw wouldnt grab, was not over torquing, had the clutch set low too to test that. Checked for rot before even putting plywood down, because thats why I ripped out the old floor. I replaced a few planks with new lumber and it did it on a couple of those too. Liquid nails subfloor, then plywood, then fastners and its solid now.
 
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