Ground floor ceiling joist insulation/soundproofing

[Marvin]

Typical 4 bed semi being renovated: What BC requirement is being achieved when adding fluffy between ground floor ceiling joists. and what would be best to use knowing that its got to stay up whilst being boarded. I'm not sure if it is for sound or thermal resistance.

 

Thanks

[Bitpipe]

Soundproofing I believe. If cut correctly to size it should stay put when inserted.

[MikeGrahamT21]

Never balance insulation without support, tried it and it dropped through and had to re-do.

 

For fluffy insulation, use a breather membrane (with the direction facing underground to let moisture pass that way not the other), lap over the joists and fix battens at the bottom of each joist to hold it, then put insulation in, this will also stop airflow affecting the insulating value, and give a small degree of airtightness. For full on airtightness, then over lay an AVCL above the joists and insulation, before the floorboards go down.

[Marvin]

2 hours ago, MikeGrahamT21 said:

Never balance insulation without support, tried it and it dropped through and had to re-do.

 

For fluffy insulation, use a breather membrane (with the direction facing underground to let moisture pass that way not the other), lap over the joists and fix battens at the bottom of each joist to hold it, then put insulation in, this will also stop airflow affecting the insulating value, and give a small degree of airtightness. For full on airtightness, then over lay an AVCL above the joists and insulation, before the floorboards go down.

Hi @MikeGrahamT21 Hmm. All this for the ground floor ceiling? Where do I put the plasterboard? 

[Simplysimon]

acoustic insulation between joists to cut down sound transmittance to upper floor. for a better job place resilient bars across joists and fix  p/board to them

[MikeGrahamT21]

2 hours ago, Marvin said:

Hi @MikeGrahamT21 Hmm. All this for the ground floor ceiling? Where do I put the plasterboard? 

Sorry! Thought you were on about the ground floor floor! Ignore me, though airtightness membrane maybe still needed depending on what your trying to achieve 

[DonkeyTable]

I have used resilient bars and 15mm sound block plaster board. Layed on top is 100mm Rockwool sound bat (not the cheap stuff). At the edges of the ceiling you must seal the bar mounted plasterboard with acoustic/fire proof sealent. I used Fsi tubes, loads of them. I havent bothered with strips on top of the joists. The effect is very good. Ive done this as I have fixtures for surround sound and large panels in all inhabitable rooms. 3 miles of cat 6 laid at the moment, 4 cables to each TV point, plus a shotgun sat cable. This will go with the whole house audio. Resilient bars go up first, then the plaster board then the Rockwool. The Sound bloc is a flag ship product. I have Wolf Easi joist so I can run the first fix central heat after the plasteboard goes up.

 

If you have inset lighting that destroys the acoustic isolation. Ive gone for surface mount. The ceiling level is fantasticly flat, even the inspectors said that. No inset back boxes in the plaster board either. Any holes bypas your required effect.

 

Dont double up on the plaster board as some people say to do. 15mm Sound block plasterboard is damn near 40Kg a sheet, double up and its 80Kg. This may over strees the joists. I havent used a membrane other than over the kitchen or shower rooms.

 

Now if Mike Graham gives me good news to my message about the manifold, I can stop thinking about where to shove the thing.

Edited February 10, 2022 by DonkeyTable
More info.

[MikeGrahamT21]

28 minutes ago, DonkeyTable said:

I have used resilient bars and 15mm sound block plaster board. Layed on top is 100mm Rockwool sound bat (not the cheap stuff). At the edges of the ceiling you must seal the bar mounted plasterboard with acoustic/fire proof sealent. I used Fsi tubes, loads of them. I havent bothered with strips on top of the joists. The effect is very good. Ive done this as I have fixtures for surround sound and large panels in all inhabitable rooms. 3 miles of cat 6 laid at the moment, 4 cables to each TV point, plus a shotgun sat cable. This will go with the whole house audio. Resilient bars go up first, then the plaster board then the Rockwool. The Sound bloc is a flag ship product. I have Wolf Easi joist so I can run the first fix central heat after the plasteboard goes up.

 

If you have inset lighting that destroys the acoustic isolation. Ive gone for surface mount. The ceiling level is fantasticly flat, even the inspectors said that. No inset back boxes in the plaster board either. Any holes bypas your required effect.

 

Dont double up on the plaster board as some people say to do. 15mm Sound block plasterboard is damn near 40Kg a sheet, double up and its 80Kg. This may over strees the joists. I havent used a membrane other than over the kitchen or shower rooms.

 

Now if Mike Graham gives me good news to my message about the manifold, I can stop thinking about where to shove the thing.

Good news delivered ??