LVT onto floating floor

[crazydaze]

Thanks Dazlight, didn't know such tool existed, going to invest.

New thoughts and would appreciate further feedback on the project. I've worked that if I 6mm ply the whole 22m2 (subfloor) and as dazlight pointed out screed 4-5mm ontop of this, I'd then need to screed 6mm + 4-5mm on the 24m2 concrete extension floor, meaning something around the £800 mark just for levelling screed.

Suddenly this is amounting to a huge amount. Without cutting corners, I'm looking at the current wooden subfloor it's tongue and groove plywood it doesn't move only at the x2 door threshold part where there is no tongue and groove. I'm rethinking if the plywood is a good idea or not, or if there is another way here. The floor doesn't move only when say the washing machine is on vibrating most of that area.

Can I cut and remove the thresholds that are not using tongue and groove and replace with sand/screed? My idea here is to go without the 6mm plywood altogether providing a huge cost saving on self levelling screed, again without cutting corners would like to know others thoughts.

Couple of pictures however understand that someone would need to view this in person to get a feel for the work required.

Where extension meets subfloor:

View attachment 355463

Door threshold movement:

View attachment 355464

Ply wood on subfloor:

View attachment 355465

I'll be laying Karndean herringbone if that makes a difference.

Dazlight's advice is absolutely spot on and the correct way to make sure the Herringbone does'nt go all over the place.

Technically, you 'could' use something like Mapei Renovation screed over the base chipboard according to Mapei's specifications but it would be imperitive to use their primer and a fairly big prayer that it all bonds to the floor correctly.

Laying these premium Herringbone LVT's is not an inexpensive business and prep is so important, essentially there's a right way, and a wrong way, Ply and suiitable self leveller is really your only option.

 

[crazydaze]

Final question, with the ply wood should I cut door jams and slide underneath or work/go around this area?

Either/Or

 

[baker332]

Dazlight's advice is absolutely spot on and the correct way to make sure the Herringbone does'nt go all over the place.

Technically, you 'could' use something like Mapei Renovation screed over the base chipboard according to Mapei's specifications but it would be imperitive to use their primer and a fairly big prayer that it all bonds to the floor correctly.

Laying these premium Herringbone LVT's is not an inexpensive business and prep is so important, essentially there's a right way, and a wrong way, Ply and suiitable self leveller is really your only option.

Thanks Crazydaze, good info especailly about the primer if going down that route.

Is there a reason ply is the selected type of wood here, assumption is that the self leveling compound adheres to it better? Would primer not be required here too?

I'm still thinking even if I use the 6mm plywood through the door thresholds there is still going to be some movement as it doesn't feel like there is support underneath. I'll likely rip this area up and do some deep level screeding instead here.

Still in two minds whether to remove the ply and screed the whole lot at 5-6mm but your suggestion on a prayer doesn't sit well .

Some costs for this project roughly so far based on 50m2:

- Floor £1500 Karndean herringbone
- F48 £150
- Self leveling all in around £700 (if screeding the lot)
- Plywood £140

Total
£2500

Rough quotes to fit have been around £5000 or roughly worked at £100 per m2. Although on their suggestion only laying ply on the subfloor then self leveling the concrete not the ply.

 

[dazlight]

You could use uzin 630 primer. Then just screed it all and no plywood.