# Laying a Subfloor Over Existing Plank Subfloor



## JR Shepstone (Jul 14, 2011)

Hey all,

I've got a question about laying a new subfloor over the existing plank subfloor. 

I thought I saw somewhere here, and I did, about gluing/not gluing, and nailing/not nailing into the joists. Unfortunately, that thread derailed and turned into a pissing contest.

So what is it? Glue down or not? Nail into the joists or not? Also, give me the why/why not if you can.

Thanks


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## A&E Exteriors (Aug 14, 2009)

I think not nailing into joists would be stupid, when we do the same thing on a roof, We always nail to the rafters to make it structural. 

I would imagine the same applies for subfloor. I don't necessarily break on the rafters, but double/ triple nail the seams depending on the plank size. 

I would also imagine gluing it down would be a plus


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## Walraven (Jan 24, 2014)

I'd be curious to hear why you wouldn't nail to the joists.


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## Splinter (Apr 5, 2005)

The reason for NOT nailing into framing is isolation... Useful for tile guys who want as little substrate movement as possible. 

I would still hit the joists over a plank floor because the planks are usually so dried out and brittle that they crack when you drive screws or nails. If the existing subfloor was plywood, then yes, I'd stagger the joints and avoid the joists.


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## Golden view (Feb 16, 2012)

True about tile. Many manufacturer instruction books and industry organizations (tile council of North America) detail NOT screwing into joists, but this is generally for underlayment, not another layer of subfloor.


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## AustinDB (Sep 11, 2006)

I've glued and screwed new subfloor over existing. the glue was to make it a single bonded unit and I didn't want it to squeak. there were no squeaks 12yrs+


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## Morning Wood (Jan 12, 2008)

I remember that thread, and it was discussing more tile underlayment as has been mentioned. If you are nailing ply over old board subfloor I would definitely nail into joists. I think I'd renail the old boards first too. Might screw the ply down. Subfloor adhesive wouldn't hurt.


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