Green Building Forum - How to fit chipboard flooring!

How to fit chipboard flooring!

Osprey — Wed, 20 Dec 2023 18:38:21 +0000

I am going round and round on this.

I took up a 1920s suspended wood floor last spring, added insulation, and laid 22mm chipboard to finish. All was squeak free until the central heating (rads) came on, when one area, over the hot pipes started to squeak.

I look up the subject online, and I get the following

a) leave expansion gap of 10mm around room edge
b) glue board t&G AND glue to joists AND use many screws (including every 150mm around the edge)
c) have water/vapor proof membrane over joists, below chipboard, minimising penetrations

These are mutually exclusive. Why have and expansion gap if everything is glued and screwed so much? But I suspect expansion may be the cause of my squeak! And you cant glue to joists if you have the vapour barrier between, which would be full of screw holes anyway!

I do wonder if a fully floating floor, no screws, but T&G only glued, might be a better solution.

Anybody got any practical advice and experience, please?

How to fit chipboard flooring!

revor — Wed, 20 Dec 2023 19:12:18 +0000

is it ground floor or first floor. presume GF?
Are you sure it is the boards that are squeaking and not the pipes rubbing on cutouts in the joist. I have had this happen in a previous house

Posted By: OspreyI do wonder if a fully floating floor, no screws, but T&G only glued, might be a better solution.

The boards glued and screwed to the joist form a structural entity and it is a must. You can lay a floating floor over this if you want. (It is what I have done battened out, laid insulation in between and UFH pipes in groves with engineered flooring over

There is a special adhesive for gluing down chipboard flooring forgot the name but google something like caber board fixing instructions you should find it in there. You use this adhesive (its flexible) on the joist and pva on the T&G. You knock boards together with a sledgehammer you will see them pulling up tight together this way. You only screw down one edge of each board using special screws that avoid jacking of the board against the joist.

How to fit chipboard flooring!

Peter_in_Hungary — Wed, 20 Dec 2023 19:26:45 +0000

Posted By: revorYou knock boards together with a sledgehammer you will see them pulling up tight together this way. You only screw down one edge of each board using special screws that avoid jacking of the board against the joist.

But use an off cut of the T&G with the mating edge into the T or G as appropriate and hit the flat edge of the off cut - to avoid damaging the mating surfaces.

How to fit chipboard flooring!

djh — Wed, 20 Dec 2023 20:35:00 +0000

The adhesive to use is a D4 (e.g. Caberfix). It's a PU glue and it's used for both fixing to the joists and for the T&G. You screw one long edge and one short edge, and obviously both edges of each type on boundaries.

Expansion gaps are needed because e.g chipboard and other timber materials expand differently to bricks and masonry. The floor as a whole must be free to expand. (Joists aren't tight against the walls I think.)

Squeaks are often due to a failed section of glue line.

How to fit chipboard flooring!

fostertom — Wed, 20 Dec 2023 23:20:29 +0000

Or a succesful mouse

How to fit chipboard flooring!

Osprey — Thu, 21 Dec 2023 11:29:53 +0000

Thanks for replies

1) No, the pipes are not squeaking. They are wrapped in their own insulation, and do not through the joists at the noise spot
2) Of course the joists have a gap at then end (mainly to isolate from the walls, but I suppose maybe some for expansion) but it makes no sense to add more gap for the chipboard if it is bonded to the joists!
3) I have seen the phrase 'glue and screw to the joists to form a structural entity' on line, but I cant really see the relevance (or why it is a 'must'). As the chipboard is a different material to the joists, with different expansion rates etc, there will be stresses. Are we trying to overcome the stresses (strong glue) or relieve them (expansion gaps)?
4) Everybody seems to ignore point c of my original post. Personally, I put the membrane over the chipboard, but nearly every video showing how to install insulation has it UNDER the chipboard, and no gluing to the joists.

(I am well aware of Caberfix)

How to fit chipboard flooring!

djh — Thu, 21 Dec 2023 12:18:21 +0000

Posted By: Osprey2) Of course the joists have a gap at then end (mainly to isolate from the walls, but I suppose maybe some for expansion) but it makes no sense to add more gap for the chipboard if it is bonded to the joists!

The chipboard needs a gap around it just as the joists do. Whether you see it as 'more' or not is a question of words I think.

3) I have seen the phrase 'glue and screw to the joists to form a structural entity' on line, but I cant really see the relevance (or why it is a 'must'). As the chipboard is a different material to the joists, with different expansion rates etc, there will be stresses. Are we trying to overcome the stresses (strong glue) or relieve them (expansion gaps)?

The joists have no strength against skew, so the floor is the only thing keeping everything square. Hence the need to bond the floor to the joists. There's no conflict between wanting to keep a car in one piece and not have it hit anything, is there? Same for the floor.

How to fit chipboard flooring!

owlman — Thu, 21 Dec 2023 13:03:55 +0000

To glue or not to glue, that is the question, and one sure to divide opinions.
Perhaps more important is to ensure the joists are well strutted/noggined and the chipboard is indoor acclimatised. All wood moves, period. Try and accommodate that movement at every stage.
On one first floor job I laid a thin self adhesive expanding tape onto the joists before screwing the T&G ply flooring down. This was primarily for acoustic reasons but I believe it also worked on allowing silent movement between what are effectively two differing substances.

How to fit chipboard flooring!

Osprey — Thu, 21 Dec 2023 18:29:41 +0000

Posted By: djhThe chipboard needs a gap around it just as the joists do. Whether you see it as 'more' or not is a question of words I think.

My point here is that although the joists may expand the same amount (or not) lengthwise, they certainly are not width-wise, (usually along the length of the chipboard sheet). So any expansion is being prevented by it be screwed to the joists.

How to fit chipboard flooring!

Osprey — Thu, 21 Dec 2023 18:40:37 +0000

Posted By: owlmanTo glue or not to glue, that is the question, and one sure to divide opinions.
Perhaps more important is to ensure the joists are well strutted/noggined and the chipboard is indoor acclimatised. All wood moves, period. Try and accommodate that movement at every stage.
On one first floor job I laid a thin self adhesive expanding tape onto the joists before screwing the T&G ply flooring down. This was primarily for acoustic reasons but I believe it also worked on allowing silent movement between what are effectively two differing substances.

Aha, useful.

Yes, gluing and screwing, particularly as the sheets are at right angles to the joists, doesn't seem to be 'accomodating' the movement.

It does not seem to be clear (looking on line) where the squeak actually comes from - movement over screws, chipboard-joist, chipboard-chipboard joints etc. Everybody seems to claim different reasons. Anyhow, I was thinking about using acoustic tape (although you used ply, which I thinks is less squeaky anyway.)

I was thinking of something like https://www.affixit.co.uk/green-glue-tape.html?

How to fit chipboard flooring!

djh — Thu, 21 Dec 2023 20:07:37 +0000

Posted By: OspreySo any expansion is being prevented

You can't prevent expansion! It happens. All you can do is anticipate the effect of that expansion and prepare for it.

How to fit chipboard flooring!

Osprey — Thu, 21 Dec 2023 20:25:42 +0000

Posted By: djh
Posted By: OspreySo any expansion is being prevented
You can't prevent expansion! It happens. All you can do is anticipate the effect of that expansion and prepare for it.

Precisely! So any screwing and gluing is going to fail. And make squeaks.

How to fit chipboard flooring!

tony — Fri, 22 Dec 2023 06:06:27 +0000

I never had squeaks only nailed with no glue, once er had to go back in 29 years , and remove a block under a threshold as the joists had shrunk and left it higher than the joists causing a bump in the floor and some noise

Nice solid joists gaps all round, pipes ever in contact with any wood.

How to fit chipboard flooring!

djh — Fri, 22 Dec 2023 10:43:46 +0000

Posted By: OspreyPrecisely! So any screwing and gluing is going to fail. And make squeaks.

Well clearly you know best so I'll stop trying to help.

How to fit chipboard flooring!

owlman — Fri, 22 Dec 2023 10:49:01 +0000

For Osprey:
https://www.affixit.co.uk/green-glue-tape.html?

I didn't use that particular brand, just ordinary expanding tape but your stuff looks like it's made for the job and will provide the "slip" needed to accommodate silent movement. Is it possible to isolate one or more individual screws where the squeak is? It may be that a screw has gone into a knot creating tension.

( A woodworkers anecdotal tale: ) I once removed a poor condition chipboard floor above a hallway. All went well until removing one screw caused a fountain of pressurised mains water. After much cursing, and piss wet through, I discovered that the offending screw had very slightly bitten into the wall of a copper pipe but re-sealed itself, it must have been like that for years. I guess the subsequent build up of limescale had also added to the seal.
After that experience I always put the small metal protector plates on the joist top, directly above where pipes and cables go through joists.

How to fit chipboard flooring!

revor — Fri, 22 Dec 2023 14:31:09 +0000

When I did our build the 1st floor was engineered posi joists with glued 22 mm caber boards. There was about 160 sq M involved. I had one squeak and that was traced to a "loose" joist end in a hanger. Fortunately I had a loose flooring board there as I still had to run some cables through and below was not yet plaster-boarded. I have had no issues after that at all. The point I am trying to make is that the companies that make the stuff will have done development and testing so they can with certainty claim if you do it like this you have no problems. The flooring joists came with a spec to do it in a certain way otherwise the floor will have had no warranty. Why would one want to do it any differently?

Posted By: owlmanAfter that experience I always put the small metal protector plates on the joist top, directly above where pipes and cables go through joists.

I believe this is a requirement of building and wiring regs when you notch timber to pass cables through. It should be minimum of 3mm thickness even thought this will not prevent shot fired fixing

How to fit chipboard flooring!

Osprey — Fri, 22 Dec 2023 15:22:05 +0000

Posted By: owlmanFor Osprey:
https://www.affixit.co.uk/green-glue-tape.html?

I didn't use that particular brand, just ordinary expanding tape but your stuff looks like it's made for the job and will provide the "slip" needed to accommodate silent movement. Is it possible to isolate one or more individual screws where the squeak is? It may be that a screw has gone into a knot creating tension.

I have more floors to do, so I am trying to avoid more squeaks. The one I have will have to wait for now (its under fitted carpet)

How to fit chipboard flooring!

djh — Fri, 22 Dec 2023 18:05:58 +0000

Posted By: owlmanAll went well until removing one screw caused a fountain of pressurised mains water.

Years ago we were converting an old school building and when the carpenters were replacing the upstairs floorboards they managed to do similar. Great fun for those who didn't have to fix it!