# Forum Home Renovation Flooring  Levelling particleboard floor ready to lay engineered timber floor

## jfalkows

Hello! I've often browsed Renovate Forum for inspiration though have never posted, so here goes. 
I plan to lay an engineered timber floor in herringbone pattern over an existing particle board floor, which is the substrate for the whole house. The area around 85-90sqm spanning 3 main living areas that all flow together (sort of open plan). The boards are tongue and groove 600x120x21mm, with 6mm timber on top and the base is timber ply. The advice I've been given is to use both secret nails and timber floor adhesive, I believe because of the smaller herringbone boards and the particle board. 
I've got all previous floor coverings off and am just down to the particle board as I write. I've run a straight edge and a very tight string line screwed to the floor and have noticed a few ups and downs. So far, the biggest variation I can see is about 5-6mm over 1.5-2.0m, which is larger than the tolerance of 3mm over 3m. I plan to spend some more time assessing the full area but basically, I'm looking for cost effective options to level out any major variations. I'm not trying to get anything level, just flat enough within tolerance. 
I know there are many self-levelling compound options but I'm not sure if these will be suitable. For example, I know that Lanko does not have any suitable compound for timber substrates (as confirmed by Technical Services) and their advice was to lay ceramic tile underlay (i.e. Fibro) and then mentioned priming and using one of their compounds. Though this could work, I think this will cost me way too much for such a large area! 
Anyway, I could go on and mention a few other thoughts based on my research, but basically what I'm after is some advice from anybody who has had a similar scenario of levelling a particle board floor on some not only cost effective but quick ways to sort this out.  
To rip out the existing particleboard and replace it I feel would be overkill, so hoping people have some good tips in particular to fill the dips (I can sand down some of the rises). 
As mentioned above, the variations aren't massive, but there are quite a few of them and they... well... vary  :Biggrin:

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## Spottiswoode

I was going to say sand or plane down the high spots, but it appears you've got that covered.

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## Marc

When we did our place we used long T&G boards and we had some wild up and downs. The worst was a step between two areas where a wall had been removed. We made two strips of ply some 300 wide in two different thickness to step down the difference and make the transition smoother. 
High points can be planed down providing you don't go troppo. Low points I would attempt packing from below if at all possible. Not easy if the yellow tongue is glued down. You can crack the glue very carefully when you identify the spot with a bit of 4x2 right next to the joist and carefully crank up with a car jack with the emphasis in carefully. 
Large lows may respond to packing the joist itself.

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## Optimus

I presume the house is on piers? 
If so, do similar to what mark said, accept use a bottle jack to lift the bearers over the piers and pack them... if there is low spots in between the piers, ie: along the joists you can lift the flooring a little and run the recip saw in between the flooring and the joists to cut the nails and separate the glue and then pack and re nail. 
Alternatively you could call a restumper (won't be cost effective though)

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## ChocDog

Worth gettinga floor sander in and doing a rough sand. That will help somewhat with any gross high spots plus give you a better surface (clean) for the adhesive to adhere to. It's my understanding that it's standard practice to rough sand possibl particle board before laying. 
====

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## Marc

Yep, sure thing, forgot the rough sanding of the particleboard to help the glue. Not so sure about high spots. May be if you get a very patient floor sander, you can mark the high spots first and get him to have a go and check with a straight edge and have another go till it's good ...

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## phild01

Long ago I used a floor sander to level the raised edges of particle board, worked well.

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## mudbrick

I've hired kennards floor sander to smooth out particle board joints before and had good results. Takes only 5-10 minutes to become skilled in using the sander and maybe 2 or 3 hours to finish the job.
After that I would consider using either a timber floor leveller ( self levelling compound) or a feather edge floor putty type filler to fill the dips in the floor. The putty is nice and easy and less messy but expensive for large areas. Bunnings sell both under the Dunlop brand in DIY size kits or go to a flooring supplies place for larger quantities. 
Either way do your checks thoroughly to work out the size of the problem before you start trying to fix it.

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## Marc

I wouldn't like to glue and nail into levelling compound.

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## mudbrick

Pobably do-able but certainly something to think about. This is the latex version I'm talking about but not sure if the nails will go through normally or if it would shatter. If it was a floating floor I would even consider stud glue for filling a few low spots...

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## CraigandKate

Just a random thought here, for the real low spots could you use masonite sheeting? Just stick it down with some ultraset and then sand it to feather out the edges. Kinda like a big stud packer..

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## Marc

Low spots will prove to be doable with plywood or rising the floor ... the problem are the very high spots, higher than what you could safely plane or sand off. Then you have to lower joist or bearer and that is a pita.

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## Optimus

> Low spots will prove to be doable with plywood or rising the floor ... the problem are the very high spots, higher than what you could safely plane or sand off. Then you have to lower joist or bearer and that is a pita.

  Thats where your beloved concrete stumps come in handy! 
Can't pull the floor down with brick piers can ya?  :Doh:

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## JB1

> I've hired kennards floor sander to smooth out particle board joints before and had good results. Takes only 5-10 minutes to become skilled in using the sander and maybe 2 or 3 hours to finish the job.
> After that I would consider using either a timber floor leveller ( self levelling compound) or a feather edge floor putty type filler to fill the dips in the floor. The putty is nice and easy and less messy but expensive for large areas. Bunnings sell both under the Dunlop brand in DIY size kits or go to a flooring supplies place for larger quantities. 
> Either way do your checks thoroughly to work out the size of the problem before you start trying to fix it.

  I've never sanded floors before, but will sand the Yellow Tongue myself in my house house. I will have approx 150sqm on YT, so it makes it economical to hire the machine and sand it myself. 
Question, how close to the edge did you get using the floor sander? I'm not going to bother using an edger for the Y/T. 
Also what grit did you use? I'm assuming the roughest paper will be sufficient.

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## mudbrick

Yep, I was a floor sanding virgin too but it's only particle board and seriously not much harder than mowing the lawn. Strangely the sander actually pulls YOU and your effort is spent slowing it down. The trick is getting the speed right to get the roughness/ finish you want. It will sand up to about 200mm from the wall. You don't need an edger. Worst case just use whatever sander you have at home to do the strip along the wall.
I don't think I used the roughest paper but close to it. The roughest paper they had was mega rough, I don't remember what grit I used but probably somewhere around 30?
filled several dust bags too doing my 50sq metres. ( had 1 dust bag explosion Too lol ) so get 6 or 8 bags.
Hint, ask the hire shop if they mind opening the flap to show you the drive belt before you leave. When I took the sander home the belt was already buggered and fell to bits instantly, so back to the hire shop I went... second time round all good.

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## JB1

Thanks Mudbrick, I'm actually keen on it as what could go wrong! 
Is the dust bag disposable? 
Would you be confident enough to sand your own floors in future?

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## rebuildr86

incidently, today i was going over Dribond Construction Chemicals website earlier today, a bit dissapointed with their technical data. however i took note of an interesting system they specified for your very situation. Patching & Levelling â Construction Chemicals
The product on this page called elastabond. 
it makes ur cement levelling compound slightly flexible!
I believe that makes it a perfect mix with something like lanko floor leveller 133, which has a very high tensile strength.

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## mudbrick

If I had solid wood floors I would have a go at it yes. Dust bags are paper bags like old vacuum cleaners and go in the bin when full which takes about 1/2 hour. 
If you can use a belt sander and can mow the lawn you can use a hired floor sander. Just lower it slowly and off it goes, you just follow along and steer.

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## jfalkows

Thank you all for all the great replies. Though I went quiet I definitely did benefit from the info shared.  
My solution has been a combination of a lot of things, though I did not use self-levelling compound. I also got a response from Ardex who mentioned that Arditex NA was suitable for laying on timber substrates (which includes particleboard) and you can even shoot a nail / staple through it, but they strongly advised against using floor adhesive as it will dry hard and cause failure on the levelling compound. As I have the herringbone floor, it's in my best interest to use floor adhesive and the nails. 
So I hired a floor sander and worked quite hard on getting some of the high spots down. The job was complicated a bit because part of the floor had old adhesive on it and as the sander went over it, it would heat it up and gum up the paper. The trick was to sweep the little chunks of old adhesive regularly, thus not allowing too much to accumulate on the sand paper. Note, I was using 24 grit paper as well, so just goes to show how much of a pain this glue was. I had a 3m straight edge and patiently sanded areas, reassessed, sanded some more, swore at the floor for still being off, sanded some more, etc. Even got the wife working on the sander! 
For some of the low spots, I used ply glued and stapled down and then feathered the edges. There's one quite low spot which I've identified as being a result of a bow in the bearer, so I'll be working underneath to fix that one. 
Tonight (or maybe tomorrow night) I'll start laying the floor and see how effective my levelling was. Such a crap job doing all the floor prep, but from past experience it's usually well worth it!

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## rebuildr86

theres a very good piece of information in your update. the fact ardex mentioned adhesive could hurt the compound is interesting. 
Id be interested to know if thats because timber adhesive is too rigid for the flexible compound. I suspect so but id love to know if that is the case.
or maybe its that the rigid adheaive would just fail and crack on a flexible leveling compound.
i wonder what the flexible compound would actually be good for now.... Lino?? floating floors?

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## phild01

> .
> i wonder what the flexible compound would actually be good for now.... Lino?? floating floors?

  I used the Dunlop flexible type floor leveller for a floating floor.

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## jfalkows

Copy paste from a couple of emails to Ardex: 
"If you were going to be mechanically fixing ONLY then the Arditex NA could be used. Direct fixing timber using adhesive over the Arditex NA will cause failure. We do not manufacture any other type leveller suitable for timber." 
"Arditex NA is the only leveller we manufacture that can be installed over timber, because of this the compressive strength of the Arditex NA is relatively low (so it can cope with the stress of the timber). So if timber was directly fixed to the Arditex NA using adhesive, as the adhesive dries it gets stronger and the timber adhesive will rip the Arditex NA apart causing delamination and it will fail." 
Guy was very helpful actually!

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## mudbrick

I'd guess the reason that glue is not recommended between the boards and levelling compound is to avoid transferring any stress from the floor boards into the levelling compound which could eventually pull it away from the particle board or crack or tear the compound. 
I can tell you the Arditex is strong stuff though, if only it was a little more SELF levelling though!!

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## rebuildr86

phil, ive never had the opportunity to use the dunlop one because the boss doesnt like to use 2 packs, on ANYTHING, EVER!
i think its some fear of mixing???
anyway, can i ask what ur opinion is of the dunlop in terms of self levelling consistency when mixed, compared to say, cementitious compounds like lanko mixed to a nice runny flowing mix.
My brain tells me the 2 pack would probably be a little more stiff, or viscous shall i say.

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## phild01

> phil, ive never had the opportunity to use the dunlop one because the boss doesnt like to use 2 packs, on ANYTHING, EVER!
> i think its some fear of mixing???
> anyway, can i ask what ur opinion is of the dunlop in terms of self levelling consistency when mixed, compared to say, cementitious compounds like lanko mixed to a nice runny flowing mix.
> My brain tells me the 2 pack would probably be a little more stiff, or viscous shall i say.

  It poured out but had to help it float out, even so it wasn't perfectly flat but enough to do what was needed. I haven't used levellers much but the cementious one I used over concrete still needed some help, perhaps not enough water.  I find instructions on these types of products eg like tile adhesive, tend to underestimate the water quantities and I need to add just a bit more than what is stated.

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## mudbrick

A reliable source once told me the Dunlop one is actually the Arditex one in a Handyman size kit.
Ardex does have a close relationship with Dunlop so there are a few products shared between these brands.
Mixing these things is easy with a paddle on a big ozito drill. It's the levelling that's difficult, moreso over large areas!

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## phild01

> A reliable source once told me the Dunlop one is actually the Arditex one in a Handyman size kit.
> Ardex does have a close relationship with Dunlop so there are a few products shared between these brands.

  Correct, now I remember being told that at the time I did it.

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## rebuildr86

ive always wondered why ardit (dunlop products) and Ardex the company had such similar names. 
phill, yeh i always go to the extreme of the recommended runniness, they say if it foams its too watery, so i get it just to foamy, then add a bit more product and mix it well. ive made the mistake of using it (lanko 133) without primer. i made that mistake once. now i carry ultraprime 5L with me in the van at all times and simply add a day to any job scope. the primer makea all the difference. u can just pour it and watch it creep over the floor. it makes the surface tension at the front of the "lava face" pull the rest of the mix over itself and keep spreading.

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