I need to change my floor build-up - help!

[Adsibob]

I've just found out that the Cellecta XFLO Micro FF, which are foil faced extruded polystyrene boards is not compatible with my choice of finished floor, which is 14.5mm engineered wooden parquet flooring. The parquet company recommend gluing it down and Cellecta say that whilst I can glue the parquet directly to the XFLO Micro FF, it is designed for larger planks to just float on top, rather than small parquet to be glued. They have suggested adding an additional layer of plywood above the XFLO Micro FF that I can then glue the Parquet engineered boards to but that would result in this build up, which is pretty tall at 73.5mm plus adhesive. I was concerned about it's height already, and so the additional 6mm and adhesive makes it even taller:

 

14.5mm parquet

adhesive

6mm ply

25mm Cellecta XFLO Micro FF

6mm Celecta Ruberfon Impact 6 dense rubber matting (this prevents impact sound transferring to room below)

22mm T&G Egger peelclean xtra chipboard

200mm POSI Joists filled with rockwool (other than where MVHR pipes go)  

 

There must be a better way of doing this. With normal joists i could drop the UFH into the gaps between the joists and suspend it on battens, but there are two reasons I don't think that is possible here:

1. I need the space between the posis for the MVHR ducting - or is there space for doing both here? The POSI is 50mm wood then 100mm gap for ducts then 50mm wood, so space for battens and UFH would be 50mm at the very most
2. I would lose the ability to put the 6mm rubber matting under the UFH system. It would need to lay it over the UFH, which isn't ideal for responsiveness of heating system - although it doesn't have much of a U value.

 

Any thoughts much appreciated!

 

[PeterW]

What is the XFLo adding here if this is first floor..??

 

 I would - assuming joists can support - use 18mm battens at 400 centres with the pipes in between, and fill with a pug mix of 6:1 sand cement. Cap this with 11mm OSB, then your parquet. 
 

That build up of 29mm is less than your Cellecta and it’s rubber flooring and the pug mix adds a decent amount of dampening mass.  
 

@ProDave has something similar so can comment on the sound issues. 

[Adsibob]

1 hour ago, PeterW said:

What is the XFLo adding here if this is first floor..??

 

 

The XFLO Micro is described here: https://www.cellecta.co.uk/product/xflo-micro-ff/ it basically provides pipe routings and heat diffusion in a high compressive (500kpa !) easy to install package. For the 16mm pipes I'm running however it needs to be 25mm thick.

 

I'm not sure how I would do what you are suggesting as surely for pipes to go in between the joists, i would need to drill through the 50mm wooden part of the POSI and I thought the whole point of posi joists is that they can't be drilled or notched and one has to route stuff through the metal webbing.  

[PeterW]

4 minutes ago, Adsibob said:

I'm not sure how I would do what you are suggesting as surely for pipes to go in between the joists, i would need to drill through the 50mm wooden part of the POSI and I thought the whole point of posi joists is that they can't be drilled or notched and one has to route stuff through the metal webbing.  

not at all .. 
 

parquet

OSB

Pug/pipes/batten

22mm Caberdeck

Joists / insulation 

 

Clearer..??

[Adsibob]

9 minutes ago, PeterW said:

not at all .. 
 

parquet

OSB

Pug/pipes/batten

22mm Caberdeck

Joists / insulation 

 

Clearer..??

That is clearer, thanks. So the UFH still goes above the Chipboard, but rather than in the XFLO, which in my case is 25mm thick, it would go in the pug mix, which you think would dampen down footsteps so no need for the 6mm rubber. It's a small saving in height of 13mm (as 18mm battens with PUG in between instead of 25mm XFLO , and no 6mm rubber layer) but sounds like extra work. Not sure it's worth it for a 13mm saving.

[PeterW]

And a huge cost saving - price up XFLo, Rubber and 6mm ply vs battens, pug and 11mm OSB 

[Adsibob]

It's not a huge floor area as it's just in the loft, but I will wait for @ProDave to comment on sound/impact transfer.

(And before somebody tells me I don't need heating in the loft, I do - We've not been able to achieve a passivehaus standard of insulation.)

[saveasteading]

I like this design a lot, and have drawn it into my ideas book, as headroom may be a concern.

But I like the idea anyway, so simple.

PeterW:   Have you done this, or seen it done?

 

Re acoustics. The addition of the pug will reduce air-born sound, but not impact sound.

The insulation shown between joists will reduce a large proportion of airborne and impact sound.

There remains some sound of impact as there is direct, solid structure from floor to ceiling.

If the 2 floors are both yours then I think this is a decent domestic solution. 

If not, then please tell.

 

The most severe acoustic spec I have dealt with was for a music practice room adjoining a maths classroom. That gets complex and expensive, but it can be done.

Foam sheet or rockwool batt under the top board, plasterboard for density (like the pug) on the next board, and a suspended sprung ceiling. hung from the joists.

Probably not needed by you.

 

 

 

 

[PeterW]

There are a few on here with a similar setup - it works well when it’s specced properly. 
 

Sound transferance between floors is best dealt with using res bars and sound block along with insulation but increasing that mass will also help.