Ceiling insulation - what should I use?

[Bitstreams]

I'm about to replace the boarding between the beams in the kitchen and have a little scope to put some insulation above the boards (there's nothing there at the moment).
I can put in a depth of about 100mm and the beams are around 280mm apart.
I want to try and get some soundproofing (there's a loo upstairs) as well as insulation.

What should/could I use? - I don't have bags of money to spend.

Simon

 

[biffvernon]

So the priority is sound insulation rather than thermal insulation or do you want a cold loo?

 

[Lime]

For best sound insulation combined with heat insulation I'd use vermiculite.
It is a light granular material that is fireproof and can be poured into the floor space filling every little gap.

I once lived in a small cottage that was often overflown by RAF trainer jets testing out the pilots low level flying abilities.
The loft was originally insulated with fibreglass and lying in bed was often like sleeping on the Gatwick runway.
The noise was very loud.
However for other reasons I changed the fibreglass for vermiculite (it's sold under several different trade names) and it was noticeable that the next overflying jet noise seemed as if it was coming from the windows rather than directly overhead.
It is a good sound insulator.

 

[Bitstreams]

the priority is sound insulation really.

I can't use vermiculite as I'm insulating from below - any other ideas?

Simon

 

[ian]

I'm thinking of sound insulating between a sitting room and a bedroom,. I am contemplating using 50mm rockwool batts, the sort Wickes sell as a push fit between the joists, finishing off with Heraklith BM board attached to battens. This will then take a thin lime skim so I understand. Both of these materials are claimed to have good sound proofing qualities. I am not sure whether to use the 15 or 25mm board. My local Ridgeon's comfirmed that the board should be available here as they are now supplied by Knauf, even though they are only detailed on the Knauf European website, not the UK one. Due to the spacing of the joists - 360mm, with the boards 2000mm x 500mm, the most economical use of the boards seems be to cut then across the 500mm direction into 360 x 500mm slabs, giving 5 slabs and waste of 200 x 500mm, rather than a waste of 140 x 2000. I would still need to fill in at the end as the joist lengths are 2300 long. Does anyone think it is a problem to have 4 joins along the infill instead of 2?

 

[AMc]

If you're insulating from below then I would consider Kingspan/celotex/isotherm boards. You can cut them to fit and infill with expanding foam to create a solid layer. Low frequency sound will travel through the joists unless you isolate the floor above or ceiling below but higher frequencies travel through air - so you need to minimise air gaps where ever possible.
Mineral wool etc will obviously work too, but you get lower thermal insulation per cm and I can imagine it would be a pain to install from underneath.

I have heard good things about http://www.secondsandco.co.uk/ but never used them, I've been buying isotherm by the lorry load recently from Sheffield Insulations as I get a great trade discount.

@ian - more joins is always bad for airtightness but with internal insulation I wouldn't worry in your situation if you butt the batts up hard against each other. Alternatively solid boards come in 1200x2400 sheets so your wastage with them might be smaller?

 

[MdB]

Shortly (*), I will be relaying floorboards. Is it worth putting a layer of something on top of the joists to help stop sound travel? We won't be putting carpet down upstairs so I'm a bit worried about the noise that traffic upstairs will make.

(*) sometime in the next 10 years...

 

[Penners]

Sound insulation is a b*gger. In order to do it really effectively you need to start from scratch with a complete redesign of your ceiling structure. Retro-fitted materials can have some effect, but I'm afraid there is no perfect solution. There's an awful lot of "suck it and see" involved, and you can end up spending a lot of money for a minimal improvement.

Broadly, I agree with Lime that vermiculite is probably going to give you passable results - within what is achievable. Any rigid material is always going to have a certain tendency to resonate, so a loose fill is probably a better bet. However, do try your best also to completely seal any air gaps between you and the sound source.

You might have some additional success by laying acoustic matting on top of your ceiling panels before you attach them to the counterbattens (ensuring that the matting extends right to the edge of the panel, so that it is sandwiched between the panel and the battens), but it's impossible to know how much additional effect this would have, in exchange for the additional cost.

 

[CHRIS]

My local Ridgeon's comfirmed that the board should be available here as they are now supplied by Knauf, even though they are only detailed on the Knauf European website, not the UK one.

I am near to you by the sounds of your builders merchant, I would try SIS on the ring road around the airport in the black barns before the pub at Mole Hill Green as they do great deals on insulation.

 

[chuckey]

I "sound insulated" from underneath, a bathroom floor from the ceiling of our kitchen. I pushed in two layers of 6" glass fibre. The only noise we ever hear in the kitchen is direct mechanical vibration, like when the loo seat is dropped or funnily enough the squeak of some one foot in the bath. The more unpleasant sounds are totally absent.
There is no reason why celotex et al, insulate sound energy. They are a lightweight material with no sound diffusing powers whatsoever. Looking at the acoustic insulation sites on the web, the rules are:- 1. Seal absolutely every air path through or around your area. 2. Use 4" glass fibre quilt. 3. Double up on plasterboard ( 2 X 3/8" instead of 1/2"). 4. Use acoustically isolated plasterboard, mount boards on rubber. 5. Use double studwork, mounting boards on different studwork. 6. Incorporate sheet lead between the boards. Just maker it thick and heavy, fill with sand or suchlike. They did not mention vermiculite as for walls its twice the price of glass fibre. I could see it working for a loft space as its significantly heavier then glass fibre which would be uncompressed, so not damping vibrations through the ceiling plaster.
Frank

 

[ian]

I would try SIS on the ring road around the airport in the black barns before the pub at Mole Hill Green as they do great deals on insulation.

Thanks for the tip. I will look them up.

 

[Flyfisher]

I play (I use the term loosely) in a band and we often use a local rehearsal studio. It's a converted business unit and is more "DIY" than "Abbey Road". The rooms are double stud walls and covered in carpet with double-thickness doors also covered in carpet and quadruple-glazed (I think) windows. I'm not sure about the innards of the wall construction but the result is astonishing - barely a murmur can be heard outside the rooms even though all hell is breaking loose inside.

Or maybe I'm just deaf.

 

[Penners]

Or maybe I'm just deaf.

Not everybody's first choice, but it's one solution to nuisance noise.