Sound insulation in 89mm stud walls

[CC45]

Planning for a busy few weeks, need to push the project on a bit if we are to move in within the next 12 months.

 

Need to order some before the BM shut for Xmas.....  spec was for wicked slabs but wondering if 100mm roll would be ok - it would be a lot cheaper....  Is it as effective?

 

What have you used?

 

Any words of wisdom vratefully received!

 

[chrisb]

I have just used 2 thicknesses of 100mm roll. It goes in easy. The mistake I made was to leave it a week before covering the second side with plasterboard, so the wool expanded and made that very difficult. I should have covered it straight away, which would have been much easier.

[Nickfromwales]

1 hour ago, CC45 said:

Planning for a busy few weeks, need to push the project on a bit if we are to move in within the next 12 months.

 

Need to order some before the BM shut for Xmas.....  spec was for wicked slabs but wondering if 100mm roll would be ok - it would be a lot cheaper....  Is it as effective?

 

What have you used?

 

Any words of wisdom vratefully received!

 

What has Bco asked for re thickness ? Is sound proofing essential, because if it is then acoustic control is far better with a dense batt  / slab than with loose wool. Maybe a choice between both in essential / non-essential areas? Bedrooms with bathrooms adjacent would be essential for eg.

[IanR]

I'm not familiar with the "wicked slabs" and went with Rockwool RWA45 and some very similar Flexi-Slabs. Easy to put in, 100mm bats easily compresses down to a 90mm cavity, and they're very effective at stopping sounds transferring between rooms.

 

This was discussed before here:

 

[ADLIan]

Both mineral wool rolls and slabs will do the same job acoustically. See AD E which recommends mineral wool, min density 10 kg/m³,  min thickness of 100mm in intermediate floors and 25mm in stud walls. Rolls normally cheaper than slabs.

Do not over fill studs and compress the insulation, especially with dense slabs, as this will acoustically couple the layers of plasterboard and degrade the overall performance.

[daiking]

2 things from a novice.

 

BCO advised that insulation was not required in stud walls with a doorway but I did anyway (slab type) and very unscientifically think it makes a difference.

 

Ditto ceiling areas where the builder put limited amounts of fluff (10kg/m3) do not seem to be as effective as parts where I put slab (30+kg/m3). (Although in reality there is unlikely to be a 100mm fill in the builder's fluff parts. The ceiling needs to come down to resolve but I do not have the heart for it.) 

[Cpd]

I much prefer the slab as it can be cut really accurate with a sharp knife. as mentioned you do not want both sides touching. In my ceiling / first floor i put 50mm acoustic roll then 100mm rockwool RW3 slab  and then another 50mm of the roll stuff, then a 50mm air gap and then the chipboard floor. However as previously mentioned if noise reduction is very importent to you then you need to look at a specific solution designed for this. Remember that flanking noise if not addressed will make nearly all your efforts for  nout if you do not take it into serious consideration. I would recomend the dense slab in your walls, carfully fitted with a gap on one side or other. P.s remember to use lots of acoustic mastic around and in all gaps.   

[worldwidewebs]

If you're going to be cutting slabs, this knife is superb for the job http://www.axminster.co.uk/hultafors-fgk-insulation-knife-117109

 

Normally I'd just have picked up whatever I had to hand but I can genuinely say that this made the job so much easier

[CC45]

BCO around this morning to check out 1st fix elecs & plumbing upstairs -?Plasterboard for upstairs delivered midday and now moved upstairs - even fitted one before quitting for the day.  Ordered a PB hoist - normally I just tough it out with some mates but must be getting soft / running out of mates.

 

Asked BCO about sound insulation - didnt seem that worried what I did.  I've narrowed it down to:

 

1. 90mm knauf frametherm slab 38 (as per BR spec agreed with BC).  V rough online prices seem to work out at around  £3.75/m2

2. Rockwool RWA accoustic insulation slab, 75mm is £3.71/m2 or 100mm £4.16/m2.  The 100 would be compressed by 10mm to fit the 90mm frame -I'm assuming this will not reduce the sound reduction much? Or do I just stick to 75mm?

3 knauf earthwool accoustic roll. 100mm @ £2.64/m2

 

Tempted to use the RWA in the stud walls that surround bathrooms & then use the accoustic roll else where and in the floor voids (prob upgrade the PB to 15mm on the downstairs ceilings to help reduce sound further.)

 

Need to measure up and ring around after new year.

 

A positive day on site today.

 

Just in case I don't post again - Merry Christmas to you all.

[Cpd]

As previously mentioned compressing the acoustic slab is counter productive. Upgrading to acoustic plasterboard would be a move in the right direction, detailing is essential if you want any measures to work to there full potential.  It all comes down to what you want in regard to the acoustic performance of your build. 

[BBF]

CC45 what did you go with in the end?

 

I recently filled a stud wall with rockwool RW3 then hung TecSound50 over the frame, the resilient bars over that, then single sheet acoustic plasterboard over on the bars. Mastic all the edges and gaps.

 

Surprisingly the hardest part was hanging the TecSound up.  

[CC45]

50mm rwa 45 in the timber frame, normal pb one side and soundbloc on the other side.  Carefully made sure there was an air gap between the sound insulation and the boards.

 

Seems ok to me.

 

I was surprised how much heavier the soundbloc boards were.