Best way to level chipboard hallway?

[redhexagonal]

I want to put engineered wood boards down on this subfloor in my hallway but it dips about 7mm in the middle. I think the boards need <3mm. The joists run down the length of the hallway and I guess they're not quite level.

Am I looking at taking up the sagging boards and levelling the joists before putting new board down? Or could I get away with a self levelling compound? I’m a bit worried there won’t be much holding the wall to the right up as the boards run under it and theyve already been cut on the other side (to level the joists)

 

[Deleted member 174758]

SLC is the easiest way to sort it out. Levelling the joists will actually mean lifting the entire floor and sistering the joists with something like 3 x 2 CLS screwed into the sides of the joists before relaying the floor (assuming that it isn't permanently banana shaped and will go down flat) - a LOT more work

 

[Deleted member 267285]

I I’m a bit worried there won’t be much holding the wall to the right up as the boards run under it and theyve already been cut on the other side (to level the joists)

Can you put some additional timbers in, say 2x2, or 3x2 for support?

SLC is the easiest way to sort it out.

Didn’t know you could use slc on timber - everyday a school day

 

[Deleted member 174758]

Didn’t know you could use slc on timber - everyday a school day

It isn't timber, though, it's chipboard. I've seen the floorers who work with us lay SLC onto chipboard loads of times - they normally put down a layer of liquid DPM, although I'm nor sure whether that's them being belt and braces or whether it's to overcome potential bonding difficulties (the platens that chipboard sheets are pressed on apparently can leave a small amount of release oil on the sheets)

 

[redhexagonal]

It isn't timber, though, it's chipboard. I've seen the floorers who work with us lay SLC onto chipboard loads of times - they normally put down a layer of liquid DPM, although I'm nor sure whether that's them being belt and braces or whether it's to overcome potential bonding difficukties (the platens that chipboard is pressed on can leave a small amount of release oil on the sheets)

i think I read something about using PVA on the chipboard to reduce “suction” . Do you know a brand of Liquid DPM thats suitable for preparing chipboard for the SLC?

 

[crazydaze]

6mm Ply over the composition board and then flex screed level.

 

[redhexagonal]

6mm Ply over the composition board and then flex screed level.

Do you mean 6mm ply over the whole floor? Or just the dipped bit?

 

[crazydaze]

Ply the whole floor then Flex Screed, Composition board won't take kindly to the moisture in the screed and will blow.

 

[redhexagonal]

Ply the whole floor then Flex Screed, Composition board won't take kindly to the moisture in the screed and will blow.

Ply the whole hallway? If I do that it will be at a different level from the rooms adjoining. Can I not just seal the chipbord with something waterproof?

 

[JohnD]

just to check, are any of the options you are considering better, more reliable, and less effort than ripping up the old chipboard and putting down a new floor in ply?

 

[Deleted member 174758]

just to check, are any of the options you are considering better, more reliable, and less effort than ripping up the old chipboard and putting down a new floor in ply?

All the options are less work, cost and mess than ripping up the old chipboard and laying ply (especially as that alone won't level the floor). Nice try, though, John

 

[redhexagonal]

just to check, are any of the options you are considering better, more reliable, and less effort than ripping up the old chipboard and putting down a new floor in ply?

If I knew that I wouldn’t be asking!

 

[redhexagonal]

All the options are less work, cost and mess than ripping up the old chipboard and laying ply (especially as that alone won't level the floor). Nice try, though, John

My worry with the DPM and SLC method is that the floor isn’t secured very well and I’m nervous about driving new screws into it…

 

[JohnD]

But not better

Not more reliable

Never mind, he will know better when it needs doing again.