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Discussion Starter #21
OK, so after all my readings and your great answers/contribution, I’m planning as follow:
· Install on top of my current OSB sub-floor a layer of 19/32” B-C grade plywood (at Home Depot, real thickness is 0.578”)
· I will screw it with deck screws (1-1/4) , 4” on perimeter and 8” on field – NO GLUE and no screw into the joist – Is this screwing schedule OK by the way?
· I will leave a gap of ¼” around wall, and 1/8” between sheets – Do I need to patch the screw heads and seams between sheets?
· I will install a ¼” plywood underlayment grade, with narrow crown staples (the schedule is printed on the sheet) – NO GLUE. Seam will be butted and I’m not planning to fill the staples “heads” – the vinyl tiles I’m looking at are 3mm thick
· Prime the ¼” ply with Henry 336 (bond enhancer)
· Install vinyl tiles + grout
Am I on the right track, or did I miss something important?
 

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i would screw off good and use sub floor glue for this 15/32" ply, butt everything tight (sand seams as needed), leave 1/8" gap around walls... then proceed to use the 1/4" underlayment.
 

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Pro Flooring Installer
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You never glue two layers of subfloor together. Ask any carpenter.
 

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Pro Flooring Installer
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OK, so after all my readings and your great answers/contribution, I’m planning as follow:
· Install on top of my current OSB sub-floor a layer of 19/32” B-C grade plywood (at Home Depot, real thickness is 0.578”)
· I will screw it with deck screws (1-1/4) , 4” on perimeter and 8” on field – NO GLUE and no screw into the joist – Is this screwing schedule OK by the way?
· I will leave a gap of ¼” around wall, and 1/8” between sheets – Do I need to patch the screw heads and seams between sheets?
· I will install a ¼” plywood underlayment grade, with narrow crown staples (the schedule is printed on the sheet) – NO GLUE. Seam will be butted and I’m not planning to fill the staples “heads” – the vinyl tiles I’m looking at are 3mm thick
· Prime the ¼” ply with Henry 336 (bond enhancer)
· Install vinyl tiles + grout
Am I on the right track, or did I miss something important?
Should work with no problems.
 

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Tileguy
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french guy said:
OK, so after all my readings and your great answers/contribution, I’m planning as follow:
· Install on top of my current OSB sub-floor a layer of 19/32” B-C grade plywood (at Home Depot, real thickness is 0.578”)

* 1· I will screw it with deck screws (1-1/4) , 4” on perimeter and 8” on field – NO GLUE and no screw into the joist – Is this screwing schedule OK by the way?

* 2. · I will leave a gap of ¼” around wall, and 1/8” between sheets – Do I need to patch the screw heads and seams between sheets?

* 3. · I will install a ¼” plywood underlayment grade, with narrow crown staples (the schedule is printed on the sheet) – NO GLUE. Seam will be butted (lightly) and I’m not planning to fill the staples “heads” – the vinyl tiles I’m looking at are 3mm thick

*4. · Prime the ¼” ply with Henry 336 (bond enhancer)
· Install vinyl tiles + grout

* 5. Am I on the right track, or did I miss something important?

1. Keep an eye on possible damage to the ply by the screws. I'll say ok since this layer of ply is not the finish layer. No glue under underlayment ever! Your 1 ¼" screws will automatically miss the joists.

2. Leave the gap and screw heads alone, you're gonna install another ply over this.

3. Perfect as you stated.

4. Yes, follow the underlayment directions which states to prime.

5. There's always more, but good for now.

Jaz
 

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well,,,,,,,, the only technical reason to not glue two sheets of ply is if the upper sheet is to be removed in the future.

if you have more technical reason why laminating ply using glue is bad please post, i am interested in learning.


on another DIY site someone posted thermal expansion. 0.005" across 48" section in 30F swing.

there's plenty of movement in glues, 0.005" is not enough to say "dont glue".

you dont want to glue the 2nd layer of sub floor, then dont.
 

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Tileguy
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Concrete Joe,

concrete_joe said:
well,,,,,,,, the only technical reason to not glue two sheets of ply is if the upper sheet is to be removed in the future.
You are partially correct. Under most circumstances there are only 2 layers of wood (subfloor and underlayment), in a floor system. This time there's 3 cuz the cheapa** builder used 19/32" OSB instead of ¾" or 23/32" (I wonder how he got away with that?) So technically the top layer, ¼" is the only one that may some day be removed and must not be glued.

If you actually "laminate" the 19/32" ply 100% using thin wood glue, that will be fine. But all people do is to squirt some construction adhesive from a tube and then start fastening. That is not recommended. It's not necessary, plus it can actually increase bounce cuz the beads of the thick glue create many voids. There is no reason to apply glue.

I know you use the word laminate, but is that what you really meant? Glueing is not the same as laminate. Is it the end of the world and cause French Guy a failure? I doubt it, but we should always speak best-practice here.

concrete_joe said:
you dont want to glue the 2nd layer of sub floor, then dont.
Technically the second layer is the underlayment, not the subfloor. There's only one subfloor. You could say the second layer is part of the "subfloor system", there's a difference so there's less confusion, sorry.

Jaz
 
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