floor build up questions

[Cpd]

G'Day folks, so in one of my cottages i have an open plan living area downstairs, 10x5 meters, i am in the process of upgrading the floor and need to make a decision on the floor build up. There is an existing concrete floor that is level across the whole area to within + or - 5mm but never more than a few mm in any one area.   

 

Height is limited 2390mm 

 

I have looked at various options and keep coming back to the idea of laying the whole area with 75mm of calotex GA4000 range compression strength 140kpa foam density 27-33kg/m3 with supportive timber work only in the key areas of loading then floating 22mm chipboard flooring glued at all junctions and then gluing and screwing ply / osb on top of this to create a really solid raft. I could then lay whatever flooring i wanted, which is a mix between wood and floor tiles. 

 

My questions are, 

 

Has anyone here built a floor in this manner, ie with minimal timber supports and if so how well did it perform.

Would this be a stable floor for laying tiles on.

General comments welcome as one friend i asked just dismissed it as a bad idea, without a good reason why beyond the fear of compression and tile joints cracking. So i am here to see what the mind has to say about it. 

 

So total build up would be

Concrete 

75mm calotex insulation 

25mm chipboard floor panels

12mm OSB or ply glued and screwed 

Final floor still to be decided but i have a large quantity of really nice 10mm Spanish tiles and a good pile of reclaimed 22mm flooring from a gymnasium, so a max of 22mm

i would add extra thick OSB / ply to the tiled areas to bring The finished height to that of the timber flooring.  

 

This leaves a finished room height of 2256mm  

Look forward to your input, thanks. 

 

[Oz07]

if you blind/self level a solid Conc floor then pir then 22mm chipboard floated on top it's going to be more solid than any joist floor. No deflection. No need for battens

[Oz07]

Sorry I see u weren't planning battens. Carry on!

[AliG]

I think you don't need so many layers.

 

Here is some advice from Kingspan on a similar floor

 

http://blog.kingspaninsulation.co.uk/why-and-how-to-construct-a-floating-floor/

 

You could out T&G flooring direct on top of the Celotex.

 

The problem then would be tiling, you would need two layers before the tiling probably. I have a single layer T&G floor over UFH and the tiles have popped and broken. Theoretically it is stable enough but there is too much movement.

[richi]

The crew here are laying a Visqueen Polythene DPM layer on the concrete screed, then 100mm of Recticel Eurothane GP, and then 22mm Caberfloor Moisture Resistant, glued together with Caberfix D4.

[PeterW]

If you want a solid floor for tiling and don't mind the cost, get the Fermacell flooring 

[Cpd]

@AliG yes i have concerns about the areas to be tiled but was hoping that 22mm chipboard flooring and then maybe 10mm osb glued and screwed followed by another 12mm marine ply glued and screwed  would provide a "bombproof and bulletproof" solution to prevent movement..... @PeterW have not seen this product but maybe cheeper and simpler than my solution.  @richi and @Oz07 i am concerned that a single layer of flooring will not provide adequate stability resulting in problems like what @AliG has seen.

Grateful for comments so far and look forard to further input. Thanks.    

[Ferdinand]

If you are going for tiles then the advice I have received has been 18mm ply both ways with a lot of screws to make it rigid.

 

Alternatively I have seen them just filled with ashphalt. We got rid of a step down into a room that way.

 

But out if you have a concrete base below tiles I am not sure what all that wood is about. Why not just put a DP membrane down, then insulation down -  your 75mm celotex, then fill it up with self-levelling concrete, then tile on that. Is 35-40mm concrete cover enough in these circs, @PeterW ? Or use a screed instead.

 

You could put wooden floor onto concrete directly. 

Edited May 13, 2017 by Ferdinand

[AliG]

Your suggested build up for tiles would probably be fine. My only issue was that you could lay wooden flooring directly onto the Celotex, and save headroom, but then you could end up with a noticeable step up to any tiled areas.

[PeterW]

13 hours ago, Ferdinand said:

But out if you have a concrete base below tiles I am not sure what all that wood is about. Why not just put a DP membrane down, then insulation down -  your 75mm celotex, then fill it up with self-levelling concrete, then tile on that. Is 35-40mm concrete cover enough in these circs, @PeterW ? Or use a screed instead.

 

35mm is too thin even for liquid screed - you would get cracking and movement once it starts to go. 

 

The Fermacell option is one that I have considered - it's basically two 12.5mm fermacell sheets bonded together with a 50mm step to create the joins. Fermacell at 12.5mm is very stable so I would expect this to be equally so. If you wanted even more rigidity with a slight amount of bridging you could use 2 layers of 25mm PIR laid between alternating 25mm battens which would allow you to secure the timber or Fermacell floor to the concrete below. 

[Cpd]

To batten or not to batten that is the question !  

For a small floor area there is going to be a lot of heavy loading as this cottage is a quirky place where people come and stay, by heavy loading i mean big rustic oak furniture, and when there is a gathering you can get up to 12 people piling in for a cramped shindig...... 

 

There is room to have a smaller floor build up (thus creating more head room) but i want to bring the final floor level up to that of the outside level when you come in, ie no step down. From existing concete floor to outside entry level  the optimal build up is 130mm this gives a 2225mm floor to ceiling finished level. 

 

So one option would be 

50mm batten on edge with 50mm insulation in between (600mm spacing of batten ?) batten screwed to concrete 

then cross batten with the batten laid flat 25mm with 25mm insulation laid in (600mm spacing of batten?) batten screwed to batten below

25mm chipboard flooring

22mm gymnasium flooring srewed to chipboard.

 

where there is going to be tiles put down a 10mm packer board ( ply or fermacell ) glued and screwed, that would leave 2mm for grout and then the 10mm tiles, is 2mm enough for grout ?

 

 Not sure what the other option is yet..... 

going outside to contemplate 

 

thanks for help so far.