Acoustic floor and underfloor heating

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Hi, I'm converting the first floor of a barn attached to my house into a flat. The downstairs will be part of the house, therefore, I am told, the floor will have to be an acoustic floor to comply with building regs. I would like to use underfloor heating and, to make things more complicated, I have a headroom problem with the existing roof trusses that prevents me raising the floor too much. After much googling I've come up with the idea of using a 20mm chipboard floor floating on acoustic strips fixed to the top of the existing floor joists, with a 15mm engineered floor on top, also floating. Is this a viable solution? Can you use 20mm flooring grade t&g chipboard as a floating floor?
 
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Floating floors are a tricky option and not guaranteed to do the job unless properly specced. These 'acoustic strips' are 'designed' :!: to carry a certain load. If you go under or over this load then they will 'short out'
Too heavy a load and they'll be overcompressed and might as well not be there. Too light a load and the floor will resonate like a drum. Also you will have a 35mm thick floor (heavy) what size are the joists between floors?

There are other ways to achieve this.

Use seperate joists for floor and ceiling below, ie: the top of the ceiling joists sits slightly below the flooring and the bottom of the flooring joists sit slightly above the plasterboard of the ceiling below. Should only cost an inch or two in height, but you will need twice as many joists, (although not necessarily the same size). Also use 2 layers of 12.5mm plasterboard on ground floor ceiling and fill between the floors with 4" rockwool insulation. Or even just normal loft insulation roll will do it at a push.

If the alternate joists idea isn't practical then use resilient bars on ceiling below, and fix plasterboard to this. They will need to be correctly installed though otherwise they won't work properly.
 
Bayard said:
Hi, I'm converting the first floor of a barn attached to my house into a flat. The downstairs will be part of the house, therefore, I am told, the floor will have to be an acoustic floor to comply with building regs. I would like to use underfloor heating and, to make things more complicated, I have a headroom problem with the existing roof trusses that prevents me raising the floor too much. After much googling I've come up with the idea of using a 20mm chipboard floor floating on acoustic strips fixed to the top of the existing floor joists, with a 15mm engineered floor on top, also floating. Is this a viable solution? Can you use 20mm flooring grade t&g chipboard as a floating floor?

I will be doing that soon, lifting exsisting floor boards up and putting floating floor down ( as part of a loft conversion in an upper flat ) It will be first time regarding putting metal track on ex joist. then will be putting 18mm t&g flooring down. V313 chip boards
 
Deluks said:
Too heavy a load and they'll be overcompressed and might as well not be there. Too light a load and the floor will resonate like a drum. Also you will have a 35mm thick floor (heavy) what size are the joists between floors?

9 by 3 (approx) @ 23" centres

Deluks said:
There are other ways to achieve this.

Use seperate joists for floor and ceiling below, ie: the top of the ceiling joists sits slightly below the flooring and the bottom of the flooring joists sit slightly above the plasterboard of the ceiling below. Should only cost an inch or two in height, but you will need twice as many joists, (although not necessarily the same size). Also use 2 layers of 12.5mm plasterboard on ground floor ceiling and fill between the floors with 4" rockwool insulation. Or even just normal loft insulation roll will do it at a push.

The current ceiling is spaced off the joists on 1" packers, so I could do that and not lose more that 1/2" or so of headroom. Interestingly enough there is a 3" thick layer of wheat husks sitting on the ceiling, which could have been crude insulation - there seems too much for it to have got there accidentally. Wouldn't I need special heavy insulation to go between the joists? If I separate the ceiling, would I still need acoustic strips? I have tried to find out what set-up will satisfy Building Regs via Google, but it seems to be a trade secret.

Deluks said:
If the alternate joists idea isn't practical then use resilient bars on ceiling below, and fix plasterboard to this. They will need to be correctly installed though otherwise they won't work properly.

Are they as effective as a separate ceiling?
 
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markie said:
I will be doing that soon, lifting exsisting floor boards up and putting floating floor down ( as part of a loft conversion in an upper flat ) It will be first time regarding putting metal track on ex joist. then will be putting 18mm t&g flooring down. V313 chip boards

Are you using underfloor heating? what will you be putting on the chipboard?
 
A seperate ceiling will outperform acoustic strips. You'd only need 3x2 or 4x2 to hang the ceiling on (dependent on span)
For insulation you should really go with rockwool or similar, I dunno what all that wheat is about, but you won't need to buy breakfast cereal for the next 6 months.
Resilient bar is an alternative to a seperate ceiling. Use one or the other. Not as effective as seperate but still much better than fixing plasterboards straight onto the bottom of floor joists. You screw the bars onto the joists, then fix the plasterboards to the lower flange of the resibar, but it's really important to use the correct length of drywall screw, you don't want the screws going into the joist or the upper part of the bar.
This flexi ceiling now absorbs sound waves, reducing low frequency resonance in the floor above.

I doubt you'd have to do much more than this to satisfy regs. The important thing is to make sure there are no gaps between the floors.
 

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