Soundproofing Floor with Rockwool this weekend. Advice needed.

[ado]

Hi All,

I have ripped off the Ceramic tiles in our kitchen in our upstairs flat in order to restore the existing floor boards underneath. Naturally removing this layer has resulted in an increase in the noise coming from the flat below.

Since most of the existing floor boards have been now lifted (to replace some of the damaged ones and also to identify where the pipes where), I had planned to place some insulation between the joist and then screw the floorboards back on top. I had planned to put garden mesh or chicken wire between the joists and place either 30mm high density slabs or 50mm general purpose rockwool slabs from Wickes on top and the screw the boards to the joists. However I have read some posts here that have raised a whole host of questions that I hope someone can help answer.

Is condensation an issue to be considered and dealt with this approach?

Does the rockwool need to be a certain height above the ceiling below so as to allow air to flow? Should there be a gap between the insulation and the floor boards or should the floor boards compress the insulation? My joists are quite tall so should I layer the rockwool until it reaches the top of the joists? Wickes 30mm high density slabs are twice the price to the general purpose 30mm slabs. Does it offer twice the sound proofing to justify the higher price? Finally I had planed to insulate about 75% of floor (leaving awkward areas under kitchen units etc). I was only going to do areas where the noise is quite loud. In this case is insulation going to make any difference if I don't do the complete floor?

I beginning to doubt that this is the best way to insulate the floor however I need to sort out the floor this weekend as we've visitors next week and I would not be in the good books if the floor is still in its current state next week.

Cheers A

[The3rd Earl Of Derby]

What makes you think rockwool will soundproof walking on floorboarding alone?

Try rubber matting(in conjunction with rockwool) nailed/pinned along the top of each lenght of joist,although if you wear high heels? this will still be picked up below. ;-)

[ado]

To be honest we generally don't wear shoes around the flat so I was more interested in reducing the noise coming up from the flat belows TV than reducing the noise cause by us walking on the floor. However not to be an inconsiderate neighbor it is something that I will now consider.

Cheers A

[adder1969]

I don't really know but I would have thought that whatever you do you'd want to make sure there were no gaps. I also would have though that the more mass you can get in there the better. When you put the flooring back you'd be better off using big panels rather than planks to minimise the gaps.

Be prepared for someone telling you to fill the voids with sand.

I'm *so* pleased I've moved out of my flat and into a detached house!

[The3rd Earl Of Derby]

Also to consider...

I lived in middle floor flat of a three storie house,the guy above had his TV on and the sound at a reasonable level,however because he had it sat on the corner cabinet(wood)it echoed more and it just sound muffled coming through the ceiling and was most annoying. so think on he might be hearing your TV or sound system louder than you hearing his.

[The3rd Earl Of Derby]

I can relate to that. ;-)

[ado]

[dom]

Government advice on sound insulation here:

's some simple, very down to earth advice using readily available materials.

Your original plan (high density insulation suspended at mid joist height) sounds a good one.

AFAIK condensation should not be a problem between flats - the plasterboard ceiling of the flat below should be sufficent barrier to moisture entering the floor void. However there doesn't seem to be much of a fire barrier to the kitchen below - does it meet current regulations?

conversion to flats was some time ago, you're not necessarily required to upgrade - but it might be a good time to think about it.

[marvelus]

Whats the gap for? Unless their flat ends and yours starts half way up the joists I can see no reason for all that extra work. Condensation is not an issue between warm flats.

I've read rockwool wont make much difference in this situation anyway, the sound come through the joists. you could probably replace the floorboards with more masive chipboard flooring designed for sound insulation and that would help, but you would still hear them.

[The Natural Philosopher]

Rockwool is all but totally useless as a sound insulator.

[The Natural Philosopher]

The biggest cause of sound transmission will be the air gaps inevitable in floor boards.

Put down hardboard first, and tape it all up and tape it to the walls as well.

Then put the floorboards back.

I've got a 10mm gap between the ceiling/floor in my bedroom currently. You can hear EVERYTHING in the kitchen below..

[Dave Plowman (News)]

These will help heat insulation but do little for sound. For that you need mass.

[dingbat]

Of course, especially if you add thermal insulation to something without adding a moisture barrier.

Mainly though I'd be concerned that your rockwool will have no effect on sound insulation.

Sound travels through air, through thin walls/ceilings, and through solid walls.

To stop sound travelling through air, you can use rockwool. Go downstairs, hang rockwool over your neighbour's wallpaper. It'll work fine. Or even give them an old Victorian sofa and a few aspidistras. Anything soft, fluffy, with a high surface area and mounted _outside_ the building structure will help. If you have a bunch of minimalist architects downstairs, then you're stuffed -- all hard surfaces, a hell of a racket.

If the sound is already conducted into the structure of the building, then no amount of rockwool (short of stuffing it in your ears) is going to help. You'd have to fix that by things like hanging new heavyweight false walls on the inside of your rooms, with isolation between them and the structure. Putting soft insulation into cavities will _not_ help, if the noise is already travelling through the structure.

For a ceiling, then it's tricky. Where is the sound going ? Is it going through thin plasterboard and thin floorboards ? Then maybe rockwool will help. If your floor is already strong though, and the sound has already made it into the structure, then it's really not going to do much.

Sound insulation in ceilings needs to be either designed in there, or retro-fitted from both sides. It's very hard to fix from one side alone.

[John Rumm]

Yup.

The rockwool on chicken wire will solve that problem as well.