How to secure floating floor on beam and block floor

[mark306]

Hi,

I had a water leak which meant my existing chipboard floor was removed, along with the insolation and DPM over the beam and block floor. The chipboard wasn't screwed in the concrete and was always a little bouncy.

When this is replaced by my insurer should I expect them to screw the chipboard / plywood down (Although wouldn't this then go through the DPM). or just leave it floating again?


Thx
Mark

 

[mark306]

I've done a little more research and I'm planning on doing this:

• Flexible adhesive Tiles or floorboards
  
• 18 mm TG plywood glue and joints (less flex that chipboard I've read)
  
• 20 mm TF70 kingspan or 20 mm Optim-R kingspan (There is not enough space for thicker insulation)
  
• DPM
  
• Beam and block flooring

Any suggestions for making the floor more secure ? (I don't have the depth for screed).

 

[chappers]

with just the single layer of ply floating, I would be wary as you may still have quite a bit of flex in the floor. The normal procedure for tiling over a floating floor is to use ply 15mm minimum or backer board, fixed to the subfloor at 200mm centres, then use a solid bed of S2 adhesive, I would also avoid large format tiles or narrow grout lines.

 

[mark306]

The normal procedure for tiling over a floating floor is to use ply 15mm minimum or backer board, fixed to the subfloor at 200mm centres...

Just to be clear so the 15mm goes on top of the 18mm floating floor and is secured to it ?

 

[chappers]

yep with joints staggered to the chipboard flooring below.

 

[Doggit]

Depending on your budget, I'd suggest a liquid DPM with sharp sand thrown on the floor before it goes off, then leveling the floor with Self leveling compoung (which actaully doesn't, so we'll tackle that later if you decide to do it), then use fibreboard for insulation, and top that off with a floating engineered wood floor.

 

[mark306]

Depending on your budget, I'd suggest a liquid DPM with sharp sand thrown on the floor before it goes off, then leveling the floor with Self leveling compoung (which actaully doesn't, so we'll tackle that later if you decide to do it), then use fibreboard for insulation, and top that off with a floating engineered wood floor.

That's interesting.

Well I want to put tiles in the kitchen and solid wood in the lounge. For the solid wood the supplier has advised to use an underlay with glue on it and not to physically nail the wood to the subfloor.

Now I have a few more questions (always the way).

What are the advantages of a liquid DPM compared to 'normal' one?

Why use a self levelling compound if it doesn't level? (or maybe I misunderstood you).

With your suggestion you're saying don't actually put a ply / chipboard subfloor down, just engineered / real wood straight on top of the insolation, any disadvantages to that ?

(I guess there's more than one way to skin a cat).

 

[Doggit]

A liquid DPM will stick to the floor, so that's one potential bounce point taken out.

I haven't used the underlay with glue on it, so can't really comment, but I'll have a look at them later.

If you've put down 25mm of celotex, then you've got to douse ply or chipboard down for the wood to go on to. But if you level the floor, and then fibreboard is fairly adequte with wood. Tiles are obviously colder, so you want more insulation under it, and then a surface for the tiles to grip to. And I can't advise you on that route, as I'd never take it.

Solid wood is okay for living rooms, but engineered wood is more stable in the kitchen, but you can use it everywhere if you want for continuity. Tiles are harder waring, but colder, and the grout discolours. With wood in the kitchen, you need protective felt on the chairs to stop scraping the floor, and you need to decide on brushed and oiled which can be maintained easily, or laquered wich is harder wearing, but you have to redo the whole floor to take out scratches.

SLC doesn't level on it's own, and if you're not that experienced, then you need to set pins/screws in the floor to give you a level to push the stuff around and get it as level as possible. It can be very sluggish, and doesn't level on it's own, hence I said we'd go int that later if you decided to use it.


I did a 6x3m floor recently with the method I suggested, and there's no bounce in the floor, and it's warm enough in the winter, not to need socks.

 

[chappers]

There shouldn't be any inherent bounce in the sub floor, it's block and beam, but the OP wants to introduce some insulation self adhesive underlays such as elastilon can be excellent. I have laid several floors on it. It is a great compromise between a floating and glued down floor.
Personally I would just cut down on your insulation thickness slightly and lay insulation followed by 22mmT and G over boarded with 15-18mm ply fix the whole lot together at 200 centres with screws, make sure you stagger the joints. either glue down or elastilon under the wood and a decent S2 flexible adhesive such as Bal fast flex or TA ultimate under your tiles.
Alternately you could treat both floors slightly differently and overboard the tiled area with backerboard. Your make-up there would be insulation, chipboard, cheap flex adhesive such as TA tradeflex, cement backerboard fixed at 200 centres, S2 flexible addy under the tiles.

 

[Doggit]

Sorry Chappers I obviously gave the wrong impression. I think the OP has introduced the bounce because the block and beam may not be level, and because of the layers that he's then used.

I can see where you're coming from, and that's an interesting idea, but would it raise the floor too much in relation to what he already had. Thanks for the pointers.

 

[mark306]

I should say I'm not actually planning on doing this myself but I want to be sure the builder is doing it a way I understand.

I've attached a photos of the BB floor. If I jump up and down I can feel it bouncing slightly (I've not introduced it). I'm now thinking maybe engineered wood will be best throughout. I've ordered some samples.

I've read weber floor flex is a good floor screed (and dries quickly) so tempted to get this put down first as I'm sure the floor isn't level.
So something like this:

• Engineered wood (20mm)

• Flexible Adhesive

• Vapour Control Layer

• 22 mm TG plywood

• insulation 20mm

• DPM

• weber floor flex (10mm)

• Beam and block flooring

 

[Doggit]

Over to you Chappers: I think you're more qualified for this one now.

 

[chappers]

it's a suspended floor if you jump up and down there will be some movement, but to all intents and purposes that's not where your movement will come from. It's your floor over insulation that gives the flex. I reckon that floor is decent enough to just ditch the SLC and do as you suggest from the DPM up, if your going to go with the glued down engineered.

 

[mark306]

Thanks

 

[cjard]

Ps; chapters seems to have mentioned porcelain/ceramic style tiles a few times, but I don't think they're the kind of tiles mark306 meant..

Mark, I don't see much point in going crazy insulating your floor's topside; you don't have underfloor heating, and a floor is not a huge heat loss path. Adding insulation won't mean you walk into a room in bare feet and think "mmm this floor feels nice n toasty!"

If you're after a floor with little flex, look at building it out of limited compressibility layers that are glued or screwed down. If the block and beam floor undulates a lot as you pass over the beams, consider an underlay that is available in variable thickness, laying in strips to even things out. An engineered wood floor can go straight onto it. I'm also not sure I see he value in your dpm or vcl layers.. a beam and block floor wouldn't be sat on the ground, but will likely have a ventilated airspace underneath, so what is the dpm for?

Ps; if you're concerned about the slight flex a concrete beam will exhibit when you jump up and down on it, I think you might need a bigger problem!