plywood subfloor - fixing

teflon

Hi Guys, Maybe someone here could help me. I moved into an old house 2 years ago and in the sitting room I took up the old floorboards because they were soggy. (There was lino on top of them and then carpet on top of that so the boards couldnt breath and began to rot.)

When I took them up there was what seemed like Tar under them on the on the cement and the boards which I later found out was Bitchumen and used as damp proofing years ago. I cleaned the area down a bit and got rid of all the loose bitchumen and left some because i thought it couldnt hurt, and then put polythene ( it was this heavy blue stuff that I got from a builder guy I used to know who said that normally its put down before the concrete is poured)
On top of the polythene i put the spongy underlay stuff that goes under a wooden floor and on top of that was ply (marine I think) which was to be our floor. The only problem was that I just screwed it to the cement below with no fixings or anything and then got carpet installed on top of that.

Now the ply has started to squeak so I am taking the carpet up and I have bought a really nice hardwood floor that I intend putting in its place. My question is (FINALLY) that i was going to use express (8 mm) nails to fix the ply to the concrete now and was wondering if that would be sufficient or if I should use something else.

In fairness it hasnt moved that much and has been a very busy room, its just squeaking a bit now where the different lengths meet.

GreeBo

if you are happy that you will always want the ply sub floor then express nails should be ok, but if you ever want to take them up again...

teflon

GreeBo wrote: »

if you are happy that you will always want the ply sub floor then express nails should be ok, but if you ever want to take them up again...

Well I got really noce solid wood to go on top that I dont fancy changing. Its got that aged look to suit the house. I am just worried that the express nails would start to move in time and wreck all my new floor..

teflon

anyone know if those express nails will definately work? Starting the job tomorrow after work.... eek:eek:

ircoha

teflon wrote: »

anyone know if those express nails will definately work? Starting the job tomorrow after work.... eek:eek:

if u are only tightening up the existing floor which is screwed down, then I would screw, the grip of the express nails is a fn of the concrete floor material and IMO hammering an existing screwed ply floor with express nails is not very wise due to the risk of loosening the screws and even the nails themselves
express nails work ok, i just dont think this is the correct application

teflon

ircoha wrote: »

if u are only tightening up the existing floor which is screwed down, then I would screw, the grip of the express nails is a fn of the concrete floor material and IMO hammering an existing screwed ply floor with express nails is not very wise due to the risk of loosening the screws and even the nails themselves
express nails work ok, i just dont think this is the correct application

I am planning on taking the screws out because they have started popping up through the carpet. See I didnt use any Rawl plugs when I first put them in and Just screwed the screw straight into the concrete as it seemed to hold but over time they have all come loose.

My plan is to take up the carpet tomorrow morning and take the screws out and sink express nails into teh plywood and concrete before I install the solid wood floor so I get a non moveable surface to work from. Good idea??:o

GreeBo

I dont think you want the underlay underneath the ply also, this will have give and probably contributed to the floor coming loose.

How thick was the ply? Ply thats too thin (less than 9mm) will move.

I'd lay a vapour barrier over the concrete, then my subfloor and then the actual flooring.
Do you have issues with height differences?

teflon

GreeBo wrote: »

I dont think you want the underlay underneath the ply also, this will have give and probably contributed to the floor coming loose.

How thick was the ply? Ply thats too thin (less than 9mm) will move.

I'd lay a vapour barrier over the concrete, then my subfloor and then the actual flooring.
Do you have issues with height differences?

The "underlay" I originally put under the ply was only really thin pink stuff thats normally laid under laminate boards. Would that make a difference? That was put on top of my vapour barrier. (concrete/ vapour barrier/pink underlay/ marine ply/ carpet underlay/ carpet)

The ply is Marine ply I think and was pretty dear. I think its 3/4 of an inch. That sound right? When I take the carpet and carpet underlay up I am hoping that it will be the same height as the new solid floor. If not it doesnt really bother me as I will just take a bit off the doors.

GreeBo

teflon wrote: »

The "underlay" I originally put under the ply was only really thin pink stuff thats normally laid under laminate boards. Would that make a difference? That was put on top of my vapour barrier. (concrete/ vapour barrier/pink underlay/ marine ply/ carpet underlay/ carpet)

The ply is Marine ply I think and was pretty dear. I think its 3/4 of an inch. That sound right? When I take the carpet and carpet underlay up I am hoping that it will be the same height as the new solid floor. If not it doesnt really bother me as I will just take a bit off the doors.

I guess its probably ok, but thats not what its for so maybe it should come up.

MarinePly is dear, you can also use WBP (Water & Boil Proof) ply which is a good deal cheaper and amounts to the same thing.
3/4 inch should be fine but what do you have in the other rooms, do you have door saddles? You will need to figure out the total height and work from there.

teflon

Im not really worried about the saddle boards because I put them all down myself and had to plane some of the doors to do that. Its an old house so the doors are pretty big anyway. I was just worried that express nails wouldnt hold the ply down and would start moving and destroy the solid floor i am about to lay.:eek: