tiling, underlayment, subfloor, screw length

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megadice

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Hello,

I'm installing some tiles.

I have a 5/8 plywood subfloor. I need to add 1/4 inch to one room to make it the same height as a connected entryway that is getting the same tile, which we want to be continuous.

I am using 3/4 #8 wood screws to lay down the 1/4 inch plywood. It feels like less than half get a good 'catch'

I feel like I read somewhere that any screws should not go through the subfloor (moisture/vapour coming up?) so I'm hesitant to increase the screw length but I'd love to use a longer screw. Is it OK to increase to a 1 inch or 1 1/4?

FWIW, the level below where I'm tiling is an unfinished basement. Overtop of this 1/4 plywood tiler will install ditra then large format (24x24) tiles.

thanks in advance!
 

bud16415

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I don"t think longer screws would hurt, but I would like to know what kind of wood screws you are using now also?

Welcome to the forum. :welcome:
 

Sparky617

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What is below the plywood? What are you screwing into? Concrete or wood?
 

Rusty

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Screws are a bad idea. They make the plywood pucker.
 

Sparky617

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I'm wondering if the OP is going to come back? This was his only post here.
 

gfw

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Screws are a bad idea. They make the plywood pucker.
Screws are a bad idea for plywood underlayment? Why would they make the plywood pucker (assuming one has properly countersunk)?

I'm using ring nails along the joists and screws generally otherwise because the ring nails just feel weird once they're through the subfloor.
 

Rusty

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You are never supposed to use screws in underlayment.
 

Johnboy555

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I used 1/4" Hardie board to back up the tile in my daughter's kitchen floor. There were vinyl tiles there before. I used my 1/4" air stapler and a sh#tload of staples to fasten it down. That was 20 years ago and have never had a single crack in the tile. Much cheaper and easier than screws. I wasn't sure that they would penetrate but worked like a dream.
 

Rusty

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Back in the early 70s we used special ring-shank nails for vinyl underlayment, but they are slower and more labor intensive. Air stapling is all that has been used for years.
 

Hamberg

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I explained it above. Plywood will pucker with screws and it will show through vinyl.
No, pretty sure you just said screws would pucker plywood AND "you should never screw down underlayment". I'm asking you to elaborate on how you would secure...?
 

Rusty

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Underlayment should be installed with narrow-crown staples.
 

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