Karndean on floating floor

Hello All,

Can you advise if the following is OK to do...

Need to raise a floor by 113mm to meet up with two other rooms, and the total area of the floor to be raised is 8m x 3.3m.
It's a well ventilated suspended floor, structurally sound with 18mm T&G floorboards fitted, but zero insulation beneath.

I'm looking to build up the height with 70mm Celotex, then 25mm pre-routed UFH tiles & spreader plates...then add 18mm T&G Plywood glued together....and this would all floating. Then top with Karndean (probably glued).

Is this OK?

 

Hi, sorry to be a pain but just got off the phone with Karndean and need to double check what they're telling me, as it sounds plain weird!!

Drawings to show what I'm looking to do.

After info from you guys I was moving away from Looselay, and that was kind of confirmed when they said I'd need to 100% tackify the entire area or glue it down, in case issues develop with my missus, and her need for a wheelchair at some point. So no point in loose lay then.

Then I asked about laying down onto 18mm T&G Plywood and they said that I must overlay with 6mm ply...when I asked why, they said you can't lay the planks onto the primary floor. When I asked why, it just seems its policy and the 6mm adds strength.??

Then I asked if I use 22mm T&G ply instead of 18mm & 6mm ply then the floor would probably be stronger as its a single impregnated substrate rather than two substrates being pinned together etc...but things got a bit vague after that with the suggestion that the 6mm provides protection to the surface of the structural floor....am I missing something here?

 

Building grade and flooring grade ply is different hence why the flooring trade will request the 6mm ply over laying the t&g, could always use Softlay fleece or 21 instead of the 6mm ply........

 

Thanks Adam,

I'm OK to use 21 or 22 mm Ply instead of 18 if I have to, and I've spoken to the timber supplier who assures me it's flooring grade and not shuttering type quality.

The person at Karndean basically said it didn't matter if I used 22mm T&G ply, Id still have to overboard with 6mm...is that really correct?
I've now spoken to the fitter I'll probably be using who's experienced and I've been into the local high end Flooring company, who sell Todd / AMTICO / Karndean etc...and they said this was not needed.

 

Cheers Spacey,

So even if I use 22mm T&G Ply I still need to pin / screw 6mm ply on top?....fair enough, but can you advise why, what does it do?

 

As distinctive Adam says the quality of flooring grade (sp101 or fg1) is vastly superior to the standard far eastern merchants ply in whatever thickness.
Spacey is correct, your new floor 22mm or 18mm is what is known as a sub flor and would need overlaying with 5.5mm flooring grade ply.
The sub flor is there forever and although you don’t want to think about it now the reason for overlaying with 5.5mm ply is so that the sub floor is in tact, for example in 15 years if the floor was to be changed the 5.5mm ply could be lifted leaving a nice sound base, whereas installing onto your 18/22mm plywood wouldn’t as it would be direct to the subfloor.
Much reasearch has gone into ply and your 18/22 mm ply veneers would also be at risk from delamination, so flooring grade ply over the lot is the way to do it

 

If your going to do whatever you want, it’s upto you, we are trying to advise you buddy that you are required to use sp101 or fg1 6mm ply over the t&g ply, be it 16-18-20-22mm it’s irrelevant, the surface ply will need to be grid pinned/screwed evenly into the t&g to limit the movement from beneath which you may get from a t&g ply, if a pro is happy to fit on anything else, he’s not a pro.

 

OK...it's sunk in
I'm a detail kind of person and couldn't see why adding 6mm of extra ply to an already Floor grade 22mm T&G ply would be needed...but I'm undestanding that the 22mm Ply might actually shift (even though it's glued) and that the 6mm will cover any gaps etc that develop as the Ply would be cross laid...

Cheers for sticking with me fellas!

 

I'm getting quotes coming through to lay approx 60m2 of Van Gogh (wood) down in 3 rooms, all on the same floor level throughout, all rooms will have 18mm Ply T&G floor down.

2 rooms are 3.5m x 4.5m and the other 3.5 x 8m, and will be completely empty with no skirting etc...
Quotes are for laying 6mm Ply (as specified) and then the LVT.

They are coming in at £2600 up to £3800...is it normal to get a 45% range?

 

Thanks Spacey,

They are quoting to cross lay 6mm of Plywood, then feather the joints etc...supply and lay 58m2 of VG Karndean.
I haven't been told if it's gold plated PLY..

I know I can get 58 m2 of the Karndean for £1500 plus their Universal Adhesive for £120....allowing for another £200 of materials (?) brings the flooring to about £1850, then the ply is about £400 I think....making £1300 approx.

I've been told it will take 4 days.
Not sure if they will all pin or screw the 6mm down....im guessing screw is better, but is it a must?

So I'm guessing that they are looking for £300/day on the bottom end....which sounds high to me.

The high end may also include a layer of fibre latex on top of the 6mm PLY because they talked about making absolutely sure that there were no shadowing coming through the tiles, especially in areas of sunlight..but it still comes out high.

 

....SORRY...that should be making £2300 approx

 

AND....at the top end it's looking like about £300 / day...not bottom end.

 

The quotes haven't detailed what type of PLY they'll use other than 6mm, but one I know is pinned / staples...the other is screwed down.
Just scanning the site for the types of PLY it seems FG1 is more cost effective and 'the same' as Sp101...is that correct?

Should I be insisting on using one or other of these products rather than leave it to chance?

In terms of the latex mentioned in one quote, they didn't specify what it was but when I discussed it with him he said it's 5mm thick and covers the entire surface. Would this mean that it doesn't matter what type of PLY they use?

 

To be honest all of those prices sound a little on the low side for full supply and install especially if you’re going with any kind of design work bordering etc I would be looking at £3800 before overscreeding the ply, it’s a designer bespoke floor and the fitters if they’re good should make as much money as they can for quality work.


Sent from my iPhone using Tapatalk