Putting down timber floors on the first floor - sound and heat insulation

[Dermot O'Loughlin]

Hi all,

I am about to undertake the first fix carpentry on my new build. My carpenter tells me the best way to put down the floors upstairs is to put plywood on top of the joists - then put down battens and insulation between the battens - then put down the timber floors on top of the battens. We would put insulation under the plywood (between the joists) when putting on the ceiling slabs downstairs.

Do you think this is a good approach in terms if heat and sound insulation? Can anyone recommend the type of insulation to use?

Thanks, Dermot.

[Christian McArdle]

If you're going to do all that, then make sure you choose where to run pipes and cables carefully, as you'll probably need access to them in the future.

Just guessing here, but I would be inclined to use sand instead of insulation between the battens. The between joist insulation will have easily satisfied the heat insulation requirement, given that it is an internal floor and probably only for better heating subzone performance.

I would expect the sand to provide better low frequency sound insulation resistance due to the extra mass. It'll also provide useful (but probably not certifiably so) fire spread resistance. Ensure that you allow for the extra weight of all this wood and material when calculating the required joist sizes.

Christian.

[BigWallop]

Also another little aside. Good sound insulation can be achieved by laying felt padding, like the thick felt underlay you get for expensive carpets, under a top layer of normal flooring boards. It's called a floating floor and is commonly used in sound recording studios and theatres I think.

And, as Christian says, the insulation you apply to the joist spaces should be more than enough for the thermal retention side of things.

A simple floating floor is less expensive as well.

[Hugh]

from the point of view of sound insulation, with your builders suggestion, sound will be transmitted throught the floorboards, battens, ply, and joists - there has to be a gap, and bigwallops ideas 'sounds' better. Timber is a quite good transmitter of sound - very useful to get a length of timber and use it as a stethoscope for e.g.testing if a boiler pump is working, it's also a useful primitive diagnostic tool for finding out where 'funny' noises are coming from in car engines or any home appliances. I tried to 'google' for 'The Building Research Council' but they must have changed their name - they provided me a long time ago with specifications for soundproofing. Anyone know what they are called now? Hugh

[Coherers]

Sounds like the sort of thing produced by the Buildings Research Establishment....

[Tony Bryer]

They were the Building Research Station, now Building Research Establishment Ltd trading as BRE:

[Pete C]

Hi,

I doubt you'd need much heat insulation between floors, a Google search for the building regs for flat conversion will give some idea of what is needed. If you want better than that have a look at some specialist sound insulating websites.

cheers, Pete.

[N. Thornton]

sounds like a pointless way to spend your money and time to me.

Regards, NT

[Michael Mcneil]

My first thoughts too but if he's building flats...

[N. Thornton]

Yeah, I hadnt thought of that. But if he is he cant just pick and choose what he feels like, there will be fire regs to meet.

Regards, NT

[Michael Mcneil]

Plus he'd be looking for the cheapest out.

[Dermot O'Loughlin]

I'm not building flats. This is my new home so I want to get it right. I'm not in the building trade so I just wanted to get advice on the best approach to take for sound and heat insulation. I'd like to know if my carpenters approach is way off the mark. Do you think it is?

I'll look into using the felt like stuff for sound insulation - does anyone know where i'd source it and any internet resources that explain how to do it.

Many thanks for your suggestions so far.

Dermot.

[N. Thornton]

I guess so. For heat insulation youve already got a 6" cavity there, or whatever size it is. If youve got thermal insulation to play with, putting it between the 2 floors is not a very useful thing to do with it. Loft, exterior walls, floor, under the bath, between floors wont achieve much.

You can buy purpose made stuff from laminate floor suppliers. Or carpet underlay works - if you want the extra expense for extra sound deadening.

Regards, NT

[Pete C]

Hi,

It also depends on what sort of noise are you trying to stop, eg footsteps on a hard floor or screeming kids...

Try:

cheers, Pete.