Naive question about raising floor level

[mjgreen81]

Hi,

I am currently part way through a renovation of a small downstairs WC. I have removed the old floor tiles (which were about 11mm with the adhesive) and will be laying some LVT planks which are only 5mm. I need to make up the remaining 6mm so it doesn't look like a big step down from the adjoining room.

The subfloor is chipboard.

I have never raised a floor level before, is it just as simple as laying down some 6mm plyboard on top of the subfloor? If yes, what is the best way to secure it? I am a little cautious about what pipes may be underneath the subfloor, but at the same time it might be nice to be able to remove the ply in the future if I ever needed to.

The floor is 'L' shaped. Is it ok to have one piece of ply covering the main section of floor and one covering the cut out? If yes, do I need to do anything at the point where the two pieces of ply join?

Thank you

 

[jj4091]

Easier with this

https://www.diy.com/departments/volden-5mm-wood-fibre-laminate-wood-underlay-panels-6-99m-/5063022038852_BQ.prd?storeId=1070&&&&&gclsrc=aw.ds&gad_source=1&gad_campaignid=21158206276&gclid=Cj0KCQiA4eHLBhCzARIsAJ2NZoJCS7qx60LNNoSlN1tktB8RyiQU25qyFq9Bb_TGJfbG2qhfsPSDmfsaAr-cEALw_wcB

Cheaper at it's sister company S/fix but can't post links on here. You won't notice the slight difference with a threshold bar fitted.

 

[mjgreen81]

Easier with this

https://www.diy.com/departments/volden-5mm-wood-fibre-laminate-wood-underlay-panels-6-99m-/5063022038852_BQ.prd?storeId=1070&&&&&gclsrc=aw.ds&gad_source=1&gad_campaignid=21158206276&gclid=Cj0KCQiA4eHLBhCzARIsAJ2NZoJCS7qx60LNNoSlN1tktB8RyiQU25qyFq9Bb_TGJfbG2qhfsPSDmfsaAr-cEALw_wcB

Cheaper at it's sister company S/fix but can't post links on here

The LVT Click flooring I have specifically says not to use an underlay (this was also re-advised by the shop floor worker when purchasing it)

 

[noseall]

If yes, what is the best way to secure it?

Short screws.

 

[mjgreen81]

Short screws.

I was asking for that .

I just wasn't sure if screws just into the chipboard sub floor would be enough and I may need adhesive as well.

What sort of distance apart should the screws be please?

 

[noseall]

I was asking for that .

I just wasn't sure if screws just into the chipboard sub floor would be enough and I may need adhesive as well.

What sort of distance apart should the screws be please?

About 200mm and in line with the joists. So five or six per 1.2m over every joist or about 40 per 1200 x 2400 sheet. Add a few more if there are hollow spots.

 

[noseall]

I was asking for that .

I just wasn't sure if screws just into the chipboard sub floor would be enough and I may need adhesive as well.

What sort of distance apart should the screws be please?

Be wary of pipe and cable runs though, if the screw happens to overwind.

 

[mjgreen81]

Be wary of pipe and cable runs though, if the screw happens to overwind.

I will be as careful as I can be, I have no idea where they are. Will just play it safe and be very cautious when screwing.

What is the normal depth of chipboard flooring in a late 1990s house?

 

[noseall]

I will be as careful as I can be, I have no idea where they are. Will just play it safe and be very cautious when screwing.

What is the normal depth of chipboard flooring in a late 1990s house?

Assume 18mm

 

[mjgreen81]

And what about where the plywood joins? Should I use anything to cover the joint?

 

[noseall]

And what about where the plywood joins? Should I use anything to cover the joint?

It's important that the joints with the flooring above don't clash with the ply. Rather they should bonded or staggered over.