LVT onto floating floor

[baker332]

Hi all,

I'm going to be laying stick down LVT in the near future, what's the best way to lay onto a wooden 'floating floor'?

Is there certain prep work involved including treating the wood for moisture? Or/and applying a levelling compound although the wood is dead flat?

Thanks for the help.

 

[crazydaze]

By Floating floor, do you mean into a Laminate or engineered wood type floor?

 

[baker332]

By Floating floor, do you mean into a Laminate or engineered wood type floor?

Basically it's the floor of the house upon building therefore joists, jablite between them then a plywood floorboard on top of that.

 

[crazydaze]

In that case you need to lay flooring grade SP101 6mm Ply over the subfloor, ensure it’s secured every 3 inches across every sheet, then feather edge or microcoat all the joints and any low fixings and glue the LVT direct to it.

if we were laying Herringbone, we would Mapei Renovation Screed over the Ply before installing the LVT.

We use High Temp adhesive on pretty much everything nowadays to negate any issues with concentrated sunlight, hot spots and of course if underfloor heating is specced

 

[baker332]

In that case you need to lay flooring grade SP101 6mm Ply over the subfloor, ensure it’s secured every 3 inches across every sheet, then feather edge or microcoat all the joints and any low fixings and glue the LVT direct to it.

if we were laying Herringbone, we would Mapei Renovation Screed over the Ply before installing the LVT.

We use High Temp adhesive on pretty much everything nowadays to negate any issues with concentrated sunlight, hot spots and of course if underfloor heating is specced

Thanks crazydaze.

I hadn't realised the 6mm plywood is required what a faff! Not wanting to cut corners but is there any particular reason for it? This is a ground floor with interlocking floorboards, it's not at all possible to latex directly?

Thanks

 

[crazydaze]

Technically you could Mapei Renovation screed directly over the existing Ply subfloor although you take the risk that the existing ply is stable enough to support the LVT.

Without seeing the job it’s hard to say but all the LVT manufacturers will specify SP101 6mm Flooring grade ply over the existing subfloor, fixed at 3” all over in both directions, feathered and then direct fit if smooth and sound, or, as I say if the floor isn’t as good as you’d like or if you are laying a herringbone or design floor LVT you’ll want to Mapei Renovation over the SP101 Ply to keep the design straight and true.

 

[baker332]

Technically you could Mapei Renovation screed directly over the existing Ply subfloor although you take the risk that the existing ply is stable enough to support the LVT.

Without seeing the job it’s hard to say but all the LVT manufacturers will specify SP101 6mm Flooring grade ply over the existing subfloor, fixed at 3” all over in both directions, feathered and then direct fit if smooth and sound, or, as I say if the floor isn’t as good as you’d like or if you are laying a herringbone or design floor LVT you’ll want to Mapei Renovation over the SP101 Ply to keep the design straight and true.

Thanks crazydaze, the subfloor has some movement in one area - what or how would you fix that? Is there a way? Drill through and inject underneath?

 

[crazydaze]

If it’s ply sheeting or composition boarding you need to fix it securely to the supports underneath

 

[baker332]

If it’s ply sheeting or composition boarding you need to fix it securely to the supports underneath

Thanks again crazydaze.

If I were to select the 6mm ply over the top of the existing subfloor there is another section where is meets with a concrete base and screed (extension) - How would I go about raising the level to match the additional 6mm plywood and I assume 2mm latex screed ontop of that? Therefore 8mm totals?

Is it just a case of laying more latex screed to match that of the existing portion of the house?

 

[crazydaze]

Thanks again crazydaze.

If I were to select the 6mm ply over the top of the existing subfloor there is another section where is meets with a concrete base and screed (extension) - How would I go about raising the level to match the additional 6mm plywood and I assume 2mm latex screed ontop of that? Therefore 8mm totals?

Is it just a case of laying more latex screed to match that of the existing portion of the house?

Depends on your skill set with self levelling but essentially, fill concrete area with self levelling screws and either blend at the join to the ply, or, fill to level and then lay a standard coat screed over the ply and concrete for a perfect finish.

You’ll ideally want to use a screed suitable for use over concrete and wood subfloors, we would use Mapei Renovation Screed.

You’ll want to be confident/sure that the concrete is dry and below 73% Relative Humidity before laying the LVT in that area

 

[baker332]

Depends on your skill set with self levelling but essentially, fill concrete area with self levelling screws and either blend at the join to the ply, or, fill to level and then lay a standard coat screed over the ply and concrete for a perfect finish.

You’ll ideally want to use a screed suitable for use over concrete and wood subfloors, we would use Mapei Renovation Screed.

You’ll want to be confident/sure that the concrete is dry and below 73% Relative Humidity before laying the LVT in that area

Thanks again crazydaze.

You think I could screed 8mm from the concrete with self levelling then? Then we are saying not to use levelling screed at the ply wood? Laying LVT straight onto the ply and then screeded concrete or?

 

[crazydaze]

For best results, lay ply, screed lower area to level of ply, then screed whole area over the top so it’s perfectly level. You’ll need to use a quality self levelling screed suitable for use over wood and concrete substrates, Mapei Renovation is really good and relatively affordable, Arditex Ardit NA is also an excellent two part screed but more expensive.

 

[baker332]

Thanks again crazy daze really helpful!

 

[baker332]

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

 

[baker332]

Do you happen to know where to buy levelling pegs is it worth it? Kind of like the following pins that get covered by the screed

https://www.amazon.co.uk/Screed-measuring-point-pcs-23-113/dp/B0757QKM9G