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Soundproofing a chimney !

P

peter bj

pfm Member
I have just moved into a flat where the downstairs has plasterboarded over the chimney and plasterboarded over it and mounted the tv on the wall . I am getting noise amplification and vibrations from the chimney area in my upstairs flat . In my flat the fireplace has been unused for a long while and the opening has just a hardboard insert . Any suggestions to improve things ?
 
peter bj said:
I have just moved into a flat where the downstairs has plasterboarded over the chimney and plasterboarded over it and mounted the tv on the wall . I am getting noise amplification and vibrations from the chimney area in my upstairs flat . In my flat the fireplace has been unused for a long while and the opening has just a hardboard insert . Any suggestions to improve things ?
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Blimey! This brings back memories . . .

I should be tempted to do what we did years ago when central heating became more widely adopted and turn the fireplace into a speaker cabinet. A decent 15" unit should provide the dual advantage of drowning the downstairs noise and having some of your own. Supposing of course, that you do not wish to use the fireplace for its intended purpose. If you do, substitute the decent speaker for a Rola-Celestion!:D
 
If its disused, drop loads of loft insulation down the chimney breast. You can buy rolls cheap from the likes of Wickes or B&Q.
 
The open chimney route from fireplace to roof level is not shared, ever (separate, from each fireplace to roof terminal); so if you can hear something from downstairs - unfortunately it is mostly structure-borne, little you can do about it.

Stuffing with mineral wool as above will do no harm.
 
If you have access to the floorboards and (for convenience) they run parallel to the chimney, stuffing sound-absorbent material between the joists may help. As Martin above said, the sound intrusion is more likely to be structurally carried than up from the chimney flues.

Of course, heavy underlay and carpeting may ameliorate the intrusion as well.
 
Cereal Killer said:
If its disused, drop loads of loft insulation down the chimney breast. You can buy rolls cheap from the likes of Wickes or B&Q.
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You might get problems with damp buildup in the chimney if you do that. Sealed up chimneys need a vent at the bottom so the air can circulate.
 
Miller-8 said:
You might get problems with damp buildup in the chimney if you do that. Sealed up chimneys need a vent at the bottom so the air can circulate.
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Indeed, the apartment below is where the vent 'should be' and one on every floor to be technically correct. If its capped at the top and sealed at the bottom, filling it full of insulation will certainly help reduce noise transference.
 
Just consider how much 'mineral wool' you' might need. If it's not absolutely heaps (like doing a loft), then I'd suggest higher density rockwool.
"Excellent acoustic performance"...

http://www.rockwool.co.uk/products/rockwool-sound-insulation-slab/

http://www.jewson.co.uk/building-ma...ckwool-flexi-slab-1200-x-400-x-100mm-pk-of-6/

This jewson 'trade packed product' is identical to the Wickes stocked product http://www.wickes.co.uk/Rockwool-Sound-Insulation-Slab-100mm/p/148842 other than the packaging (Rockwool have confirmed this to me on email).

You'll probably get a better price at Jewson (about £5/pack cheaper).
 
Thanks for some thoughts on this , I think rockwool in the chimney looks like the first option to try . It is probable also structure borne after having a think about it so maybe some under the floor if this does not work
 
Restricting air circulation in a chimney often causes damp problems, as condensation accumulates inside it, and can travel through masonry walls, causing damp patches to appear in rooms. Tar from the flue means that the damp is normally an unsightly orange/brown staining. Also, each room would have its own individual flue, so there should be no direct airway linking the rooms, meaning that blocking one flue may have no effect on noise transfer from another.
 
Sheep's wool, however nice an idea, absolutely cannot be recommended for insulation purposes - neither acoustic nor thermal.

(I'm a little constrained about saying why in public right now; think 'pests'; PM me if you absolutely have to know)

A slice of resin-bonded mineral wool (e.g cavity wall batt) installed horizontally across a disused flue, even two or three, will not have a material effect on moisture vapour transport in the chimney, nor be affected by it.
 
so there should be no direct airway linking the rooms, meaning that blocking one flue may have no effect on noise transfer from another
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similarly though, there's no direct airway linking ceilings and floorboards... However...!, the use of rockwool between ceiling below and floorboards (i.e. in the floor cavity) achieves sound absorption. More details on the Rockwool site I linked above. I'd say for the sake of £20 (or £40 if you want/need 12 of the blocks), then it's worth a go. In terms of venting, you could still pop a ragged vent hole in it somewhere.
 
Place an NVA amp in the fireplace, two birds with one stone ;)
 
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