Yellow Tongue Floating Floor Over uneven sub-floor

I'm laying 3600x900x19 yellow tongue in my apartment as a floating floor over the existing joist/timber/masonite sub-floor. The masonite has been glued and stapled onto the floor boards and is reasonably even. However the floor rises 10-15mm as it approaches the holes where two 3 metre walls used to be.

The original idea was to screw down all the creaks, lay a 5mm accoustic barrier and have the yellow tongue floating on top.

I don't think self levelling cement is an option here so I'm looking at sanding down the peaks as much as possible and packing up the middle of three rooms with lino before laying the insulation.

Is the yellow tongue stable enough to cope with this. It will be Liquid Nailed along all the joints and biscuited on the ends.

Is this a disaster in the making? I'm kinda hooked on my glossy dark polyurethened floor and want to make this work.

Any advice would be much appreciated.

I've never tried this sort of thing but I have done a fair bit of renovating now and have found that the further you can strip anything back the better. i.e. filling and packing and sanding etc. takes a lot of time and effort, you need to come up with a way to get the base correct before laying anything on top if possible.

It is acceptable to sand yellow tongue but not 10-15mm.

Could you rip up the masonite and add packers along the top of each joist to get them flat before laying the flooring?

When you lay yellow tongue on a normal joist floor you are meant to put a bead of construction adhesive along all the joists first. This helps keep it attached but also takes up any gaps under the chipboard ... I think you should consider that too. Get a box of 20 tubes and don't be stingy!! Good luck.

Hey Bob,

I havn't explained myself very well.

What I have right now is masonite, glued and stapled onto floor boards which are nailed onto the joists.

My plan was to leave it as it is because the masonite would be such a bugger to get up. Over the masonite, I wanted to lay 5mm accoustic insulation. And then on top would be the yellow tongue.

The yellow tongue would be the 'floating floor'. The sheets of yellow tongue would be glued to each other around the edges with something like Max Bond along with biscuits on the ends (where there is no T&G) Like any other floating floor, it would sit on the insulation without being screwed or nailed to the sub-floor. Finally I would give it a few coats of dark walnut polyurethene and that would be my floor.

For less than $1000 I was hoping for a very cool floor, no more holes, no more creaks and no more 'karaoke at 3am English back-packer neighbours'

But.

It wasn't until a couple of days ago that I realised how uneven my floor (the future sub-floor) actually is. It seems to peak 12-15mm against most of the walls and where 2 walls used to be.

So the plan was to sand these 'masonite over timber peaks' down and pack the low areas with lino before laying the insulation and the yellow tongue.

And I thought I'd better run it by you guys first to see if there were a better solution.

Bare in mind my pride can take a bigger beating than my bank balance just now so call me a fool and set me straight if I've got it all wrong.

Hey I'm all for thinking outside the square! Hopefully someone out there can help you further but I would say that yellow tongue is a lot more solid and heavy than what would normally be used for a floating floor so if doen properly I would think it could work. Just a couple more comments that you may not have considered?

- The tongues on yellow tongue aren't glued in ... so I guess you would have to remove them and glue them and replace them?
- Yellow tongue has a wax coating on it so that you can leave it in the weather for three months. I'm not sure how that would go with your polyurethene?
- Yellow tongue can be very hard to join together because they are 3600 long. On my subfloor I had to nail the first sheet down then use a sledge hammer to bang the next sheet flush at the join. You may need to think about how you will get the joins to butt up?

Hey Bob,

Thanks for that, I thought the coating was an estapol. And I had no idea about the tongue not being glued in.

Things won't be so bad manoeuvring the timber though, I'm having to get it cut in half just to get it into the building.

Wish I could get away with wood glue, I can't open a tube of contact cement with ending up covered in it.

G'day Ibay,

I'd be a bit careful about doing this. Generally using building materials for purposes other than what they are designed for is asking for trouble.

I'd strip the masonite, fix the flooring including all creaks etc. Then sand the floor flat and install a floating floor designed for that purpose. I'm sure that you can find one you like, but using particleboard as a substitute will fail.

Cheers
Pulse

I often try ideas that are outside the square, and I think your idea would work but there are no guarantees. With the size of the sheets, and since you're not using any fixings, if there is any tendency for them to warp over time then you might get raised joints or humps in the sheets that would flex as you walk on them. It's also hard to get a nice tight joint between the sheets sometimes as the edges aren't always dead straight. What I'd do is remove the tongues and plane of the coloured glue they put on the edge of the sheets, then I'd fix the edge of the first sheet against a wall. Then I'd remove the tongue and test fit the next sheet, planing where necessary. Then I'd mask the top of the sheet (to avoid getting glue all over the top of the sheets), and I'd install the tongue with heaps of light brown max bond glue in the grooves and on the sheet edges. I'd want to avoid sanding the sheets as the finish is pretty good to start with.
If you spend some time and attention getting the joints perfect, then a coat of polyurethane should bring it up like the bees knees, but of course there's no guarantees that with sheets that big floating around you might get some movement. I'd definitelly be inclined to at least screw fix right around the perimeter of the floor.

OK , here's another idea

A floor I have see used as a base and stained brown, is plywood flooring. I think the one I saw was hoop pine, but it was stained a reddish brown and then polyurethane sealed to a very hard surface. The actual surface is better than yellow tongue and should take a finish well.

As to floating - I am guessing you are trying to achieve a sound deadening effect by doing this. If this is the case, then the floating floor people would have a rating and tests to show the acoustic de-coupling provides an advanatge - as this then would allow there use in some multistory complexes instead of concrete floors. I suspect that the difference between a thick dense floor nailed down over carpet underlay for instance and a floating one would be very small indeed.

As to nailing,. nailing down with a finishing gun, or bullet heads, a quick fill of holes and then stain is going to hide the nails very well indeed - look at dark old floors - you can hardly see the nails because of the finish.

Hey Pulse

You could be right about the yellow tongue. It appealed to me because of it's cost, rigidity and smik looks with a few layers of walnut estapol on it. The test piece stopped looking like cork after the second coat. Quite an industrial look but still obviously timber. I want the wood without the floorboards. My original choice was large sheets of plywood but there were too many issues with soundproofing, joins and flexibility unless it's being layed \onto concreit.

I live in a 1930's building with no slabs between the floors. The joists supporting my floor also hold my neighbours ceiling. Noise and vibration are issues that seemed to be addressed by using yellow tongue in this way. And the masonite is here to stay thanks to the tradesman with an unnatural glue and staple fetish.

Does anyone have any ideas?

Hey Pharmboy and Pawnhead,

I should have checked the forum before pressing send. And you're right about the glue, I know for a fact that I will end up covered in it just before a sudden gust of wind flings every piece of paper in my life at me.