How to level a yellow tongue floor?

[wazza77]

I need to level a floor in my loungeroom. House was built in 1990s, uses yellow tongue chipboard floors. 

I am getting a new engineered floor ( laminate wood on mdf backing - not cheap....) put in,  which will be glued down to the existing chipboard floor.

I can take off the slight ridges where the bearers are under the floor, but the sag between bearers I may not be able to fully eliminate.

There is a max 1mm / m sag tolerance the new floor, so the salesman says.

Can I use some type of concrete based floor leveller to fill in the sag areas ?

I was concerned concrete based floor leveller would soak into the chipboard and cause it to swell, plus it might also sweat moisture and stop the glue sticking to it.

Any thoughts welcome

[EricL]

Hello @wazza77 

Thanks for sharing your question about levelling your chipboard floor. 

I agree with your concerns regarding using concrete floor levellers. Instead, I propose removing your old yellow tongue and putting in timber or plastic spacers to compensate for the sag in the timber framing. Put in new yellow tongue sheets to make sure you have a totally levelled floor. In this manner you won't have to worry about the adhesive not sticking or getting moisture contamination ruining your flooring. 

Let me call on our experienced members @Nailbag and @Dave-1 for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Good Evening @wazza77 

I would be reluctant to use a concrete leveler over timber. I would probarly go the route of @EricL's suggestion.

I have a LARGE dip in my lounge floor (Hardwood floorboardson hardwood everything lol) It was there when I bought my place and I want to fix it same as you. I will be probarly jacking up from underneath and either replacing the bearer or joists. Def wont be attempting that on my own, will be hitting up a acrpenter/builder. 

I do believe its wiser to fix before you put down the engineered floor. The more I go over your issue the more Erics solution is where I end up.

Dave

[Nailbag]

Hi @wazza77 using concrete lever probably not going to be suitable and could open up a bigger can of worms. On the edges of leveller its always going to leave a raised lip greater then your 1mm tolorance. Then you would need hone that down as the compound doesn't like to be smoothed over when setting which, is very fast.

There shouldn't  be an issue if the floor is not level across distances. It's any larger short distance dips and any highpoint the installers will be concerned about. There is only a couple off mm in the joining system of a floating floor and the thinner boars are less forgiving in how the click together than thicker ones. Any major change in level will result in board/s that wont click in to place or break at the joins if forced. 

High points can be resolved with a planer on the top surface. But if the floor level is extremely you could look at installing 3mm MDF sheets over the entire surface and use packers underneath to address major low points. But the edges will have an impact at room entry being raised slightly.

See photo below for a similar issue I once had but more extreme. I intend on laying the boards over the tiles. So first I removed the inset carpet section and filled it with MDF, I then laid a thin foam underlay over the entire floor. I can tell you that it wasn't perfect, but after removing any high points the floor went down with very few issues and any imperfections in the levels was not noticeable.  But I was the installer, and not concerned with the floor being 100% perfect as expected by the sales person.

But, before consider this and any other ideas, you could request an installer look at your floor first and advise the course of action as you could be going to a lot more trouble than needed. Remember the sales person is unlikely to have any installation experience and doesn't know what can and can't be achieved. they tend to simply quote product specs.

Nailbag

 

  

[wazza77]

Hi

Thanks for everyones suggestions.

Ironically, when i pulled up the kitchen floating floor, i found someone had used cement leveller for the top of the stairs. Ugh.

Good news is I didnt have to jack the floor up, i was able to sand it down. Pig of a job, huge amounts of dust. Wife not happy...😎. My experience is open every door and window while doing it. No ventilation and oxygen levels could drop too low in the room.

So after thinking about, I think if after sanding i still had a floor with a woof in it, I would have installed noggins between under floor bearers ( using screw in coach screws) and jacking up the sagging floor sections and inserting some shims between floor and noggins, to bring the sagging flooring up to about level, then hiring a drum floor sander from bunnings. I think this makes the most sense. If i only then had to take down the floor to say 2-3 mm , that would be ok. If it was any worse than that, I think putting sheets of mdf in and sanding it back to level might have been the go.

Also I suspect as chip board is glued together, sanding it might release glue into the air, so a Australian Standard respirator ( forget cheap flimsy dust masks....) would be a damn good idea.

Cheers

[wazza77]

Update 16/08/2024

So everything has been turned on its head

We've just had professional installers around to put down our floor , here is the sequence I observed ( but may not be 100% complete ) :

(1) Installers complimented me on my hard work of sanding the floor. Unfortunately the straight edge was using was 1m long, they had a professional 3m straight edge, were able to detect floor "woof" better than I could. Floor looked really good once it was sanded off initially   

(2) They then proceeded to coat the floor in some unknown sealer/primer using a roller.

(3) They put spray foam in all the gaps and around the floor heater ducts and under-door gaps to stop the self leveller going where it shouldn't.

(4) They then levelled the floor with Sika 4020 Fibre level which appears to be cement based leveller reinforced with small fibres.

(5) They then used Bostick Ultraset 3-in-1 glue to glue the floor boards to the concrete self leveller compound ( I don't know if they used another primer on the self leveller before glue-ing to the self leveller ? )

End result is a floor that feels almost like its been done on a 4" thick concrete slab. In essence the floor is now a glued composite material - wood, concrete, wood.

Thermally, the floor being part concrete, will suck heat from the room, so we need to get some rugs to help cover it.

Hope this might be of some assistance. There may be a step or steps missing, so don't rely on this as being 100% correct process, this is just what I observed during a short time period and I might not have seen everything.

End result :

This link ( below ) might also be helpful for people?

https://www.workshop.bunnings.com.au/t5/Bathroom-and-Laundry/How-to-seal-yellow-tongue-for-floor-lev...

[JacobZ]

Hi @wazza77,

Thanks for the update and for sharing your observations of the work carried out.

Did you have any photos of the finished floor that you'd be happy to share? 

It'd be great to see the end product.

Jacob

[wazza77]

My next job is to move all the furniture back in and replace the skirting boards.

[Dave-1]

Morning @wazza77 

thank you for the info, Love knowing how the professionals do things. I really like the idea of the spray foam to stop the leveler traveling. Brilliant!

I rem my floors looking great when I had them sanded, varnished and then when I put the skirting back on they went from great to Unbelieveable! Cant wait to see!

Dave

[Nailbag]

Hi @wazza77 I agree with agree with @Dave-1 on the expander foam as a temp barrier. Ive used leveller products many times and keeping it in one area is always an issue. I love learning new solutions.

Look forward to the finished photos.

Nailbag