soundproofing joists

johnpawl

At the moment I'm trying to decide whether to use hollow core slabs or joists in the first floor. My main concern with joists is sound transfer, just wondering does anyone know if it is possible now to soundproof joists to a decent degree? Thanks, JP.

FesterBeatty

There are a number of systems - I've specified many and seen many installed but at the end of the day you have a piece of timber, a noise of hard shoes, kids playing etc on top of a sheet of ply and that noise will travel through your joist to some degree. If you want silence then go with concrete. (i know many will disagree and will try to promote these proprietary systems - but the above is my experience)

writhen

Just to add to the above - concrete floors are very good for airborne noise transfer but you will also get impact noise transfer through them as well.

DOCARCH

Just bear in mind with concrete/hollow core floor construction, your overall floor depth will be deeper and especially if you are looking to coneal services within.

For example, if you are looking to have recessed downlighters to the underside of the floor structure, this will usuallyy involve the provision of a suspended ceiling under the concrete floor.

For sound proofing a timber floor structure I would often use/specify this type of system - http://www.gypsum.ie/pdf/p-manuals-2007/6_FloorsandCeilings/6.4_GypFloor%20Silent_feb07.pdf

mfceiling

The brother in law went with joists.
Between them he put rockwool, then on top he put a layer of ply then a layer of 25mm "planking" (gypsum product), then another layer of ply.
Did a reasonable job of stopping noise but he said if he was doing it again he would have just gotten the hollowcore put in.


Mod Edit...i named products, but i have no affiliation with them nor can vouch for their credentials.

galwaytt

substituting conc floors for wooden joists is no guarantee of anything - it's in the details.

It is entirely possible to build very quiet joist-based floors, using modern materials - the UK is a good example of good acoustic practice these days.

We've fitted joists with acoustic tape on the top, before the deck was put on, and then isolating layers, above. Works well.

At Ecobuild in London last week Knauf had a gypsum-fibreboard 'tile' to be used as a sub-floor, over an 18mm deck upstairs, and it looked like a good idea. I've heard of an 18mm wood fibreboard being used the same way.

I suppose that advantage of systems like those is that they are dry, light, and don't require thicker walls, nor suspended ceilings below, and are fundamentally 'warmer' as well.

Sound path mitigation is the key, imho, not just chucking big stuff at it.

Slig

A properly braced timber joist floor using properly sized joists can be surprisingly sturdy. Timber floors have a bad reputation for being noisy because modern floor spans are usually excessively large and bracing has not been put in at the required centres or has been cut out to allow easier access for services.

If a timber floor is put in to an above standard level (possibly using 75mm thick joists instead of 44mm) and with the correct bracing then it can be difficult to tell the difference between it and a concrete floor.

Dont forget that putting in hollowcore will not only increase the depth of the slab to accomodate services as mentioned above but may require other considerations such as thicker walls on the ground floor.

Troy McClure

If a person is putting in HRVS and looking at concrete floors, allowing you will probably have to bore big holes in the concrete for the ducting will the sound benefits of the concrete floors be negated?
Does this make it a poor choice of flooring if you want to have HRVS?
Is there a quiter alternative? and yes we want UFH.

whowantstwoknow

DOCARCH wrote: »

Just bear in mind with concrete/hollow core floor construction, your overall floor depth will be deeper and especially if you are looking to coneal services within.

For example, if you are looking to have recessed downlighters to the underside of the floor structure, this will usuallyy involve the provision of a suspended ceiling under the concrete floor.

For sound proofing a timber floor structure I would often use/specify this type of system - http://www.gypsum.ie/pdf/p-manuals-2007/6_FloorsandCeilings/6.4_GypFloor%20Silent_feb07.pdf

Hi there,

I'm considering installing the floor silent system into parts of my house (kitchen ceiling with bedrooms above). Going to lift the existing floor boards. Would the likes of this tool be suciffient in cutting the boards at the wall edges? if not can you recommend an alternative?

Also would it be wise to re-install these boards or finish with a suitable plywood?

Thanks

W.