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Insulation/board support for pug/biscuit mix in suspended floor


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Hi All,
We're having UFH in a first floor extension and I'm looking for additional detail for a PUG mix system, particularly the type of insulation recommended?

The details given to us are battens on joists (8" joists, sized for the additional load) supporting timber boards with high-density insulation and then membrane, pipes and pug mix on top.   No specification has been made regarding the insulation beyond the "high density" bit.  

Can anyone share detail drawings or proper specification for this? Or just share their own experiences?
PFA 😉

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Put the insulation between the joists.  What is below?  cold space or another heated room?  We used glass wool type insulation rather than rigid.  Supported by netting for a suspended floor.

 

A layer of OSB over the top of the joists, we used 13mm.  Battens following the line of the joists and it is these you leave gaps in where pipes need to cross over joists.  Then dry pug mix laid between joists. Finally your chosen flooring, ours was engineered oak laid onto the battens.

 

 

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4 hours ago, ProDave said:

Put the insulation between the joists.  What is below?  cold space or another heated room?  We used glass wool type insulation rather than rigid.  Supported by netting for a suspended floor.

 

A layer of OSB over the top of the joists, we used 13mm.  Battens following the line of the joists and it is these you leave gaps in where pipes need to cross over joists.  Then dry pug mix laid between joists. Finally your chosen flooring, ours was engineered oak laid onto the battens.

 

 

Heated room below. I'd like to get some insulation with acoustic properties if at all possible.  Does such a thing exist?

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All insulation has acoustic properties.  The more dense it is, the better normally.  PIR is rubbish.  We used rockwool flexi in our internal walls, seems to do the job quite well, equally suited to ceilings.  Ideally you need an air gap either side of the insulation, that helps with the acoustics.

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How about, something like 100mm Rockwool between the joists. Its main purpose is to prevent the reverberating drum effect but can double up to heat insulate in your case. 

 

Structural flooring on acoustic strips on the joists. 

 

Membrane,

 

Pipes and screed. 

 

 

If you want to do more acoustic improvements consider resilient bars underneath and greater mass of plasterboards (soundbloc or thicker boards or double board). 

 

An essential part of soundproofing is closing any air pathways so downlighters etc are best avoided. 

 

 

 

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