Sound proof ceiling

[rbirkby]

We have a bedroom above our living room between which a lot of sound travels. The bedroom floor is bare elm floorboards. The living room ceiling has no void but is simply elm/oak joists and minimal insulation (polystyrene....) glued onto the underneath of the elm floorboards.

As the joists are about 6'2" above the floor, I don't want to loose any headroom. What do most period properties use in this situation? We've already done the obvious and put a rug on the floor.

We're a lime/cob cottage, but I'm considering plasterboard between the joists and placing some acoustic wool above the plasterboard and below the elm floorboards. Is there a better solution?


Richard

 

[Schoolmarm]

The best and least destructive would be thick underlay and thick carpet.

It is annoying when you love to see your floorboards but since we lifted our thick carpet and underlay the noise in both directions is terrible.

 

[CHRIS]

I second the thick carpet and some nice thick underlay, we had the same problem with our nice wide pine boards but the noise was just terrible. We used some of the mega thick posh underlay and had a very thick NZ wool carpet laid which made a huge difference not just in the noise but in the insulation as all the hot air used to just go straight upstairs. It is now much cooler upstairs and warmer down!!

http://www.constructionresources.com/products/envelope/happystep_int.asp?PageCategoryID=8

This would be the type of thing.

 

[FamilyWiggs]

We had a similar problem. We've put in thick underlay and carpet above, and 2 layers of Sounbloc plasterboard between the beams below. It's screwed to half inch battens fixed to the beams so there is also an airgap for soundproofing of that half inch. I guess we could have filled the gap with wool or something too.

All in all it reduces the depth of the beams by about an inch - barely noticeable as we still have about 3-4 inches still visible.

I guess it would have been possible to screw directly to the floorboards if depth really is a problem, but you run the risk of movement/cracks then. If you didn't skim the Soundbloc but directly paint and mastic around the edges, you might get away with it.

http://www.british-gypsum.com/products/plasterboard___accessories/gyproc_acoustic.aspx

Robin

 

[AMc]

I guess it would have been possible to screw directly to the floorboards if depth really is a problem, but you run the risk of movement/cracks then.

I also read a web forum related to home cinema http://www.avforums.com. The subject of sound proofing used to come up a lot (with a view to keeping it inside dedicated cinema rooms).
My understanding is that fixing the ceiling directly into the floor boards above would allow sound to travel through and will negate most of the benefit of the extra mass. Sound is carried by vibrating air or vibrating objects so you need to minimise air paths (for high frequency sound) and minimise contact points (for low frequency sound).
As I understand it you need to isolate the ceiling from the floor above sharing as few contact points as possible and add as much mass to the new ceiling as you can to reduce transmission.

Heavy false ceilings and false walls - rooms within a room - are the most effective ways to reduce noise, but obviously that isn't practical in many cases...like when you want to see exposed beams and floorboards

 

[ljn]

Polystyrene is highly flammable and produces toxic fumes when it burns. Try burning a piece. It melts and rains down making a zipping sound.

An underlay such as Treadaire Technics 5 or 6 would give a good reduction in impact sound (walking, things dropping on floor etc) respectively 27 and 31 db. That would work as a carpet underlay or under a floating wood floor.

Airbourn sound (voices, tv etc) will be attenuated by filling the space between the joists with a high-density rockwool. It is the thickness and density that count, so a thin layer won't do much.

I don't think plasterboard between the joists will help much, being attached to the floor/ceiling structure, the sound would just transmit through it and it won't help much with volatile sound either.

 

[Jon Maine]

Polystyrene is highly flammable and produces toxic fumes when it burns. Try burning a piece. It melts and rains down making a zipping sound.

An underlay such as Treadaire Technics 5 or 6 would give a good reduction in impact sound (walking, things dropping on floor etc) respectively 27 and 31 db. That would work as a carpet underlay or under a floating wood floor.

Airbourn sound (voices, tv etc) will be attenuated by filling the space between the joists with a high-density rockwool. It is the thickness and density that count, so a thin layer won't do much.

I don't think plasterboard between the joists will help much, being attached to the floor/ceiling structure, the sound would just transmit through it and it won't help much with volatile sound either.

What we did was to raise the floor height by around 50mm. we than put a layer of neoprene soundblock followed by 25mm of 100kg mineral wool, it has improved things greatly. You do need to isolate the floor to the joists to stop transmitted lower frequencies, not an easy task, we did not do this. Although only the youngster playing bass music travels much the mid and high frequencies seem to have been cut down significantly.

It is also worth noting that different densities of mineral wool knock out different frequencies so putting thinner layers of different densities in would be more beneficial.

Although in your specific case unless you give yourself a lot of work the underlay option would be the best solution.

 

[rbirkby]

Although in your specific case unless you give yourself a lot of work the underlay option would be the best solution.

Thanks. My primary objective is not to cover up the uneven elm floorboards. So I'll look into Sounbloc and put up with less than ideal sound insulation.


Richard

 

[Jon Maine]

The neoprene system called soundblok (not sure about the spelling) was by far the most expensive.

There are other neoprene systems which are far cheaper and seemingly as effective.

These are the people I bought "noisestop barrier shield" from http://www.noisestopsystems.co.uk/