soundproofing floors/ceilings in MBC timber frame

[Besidethewye]

As I work my way through the next stages of my project I am going around in circles about sound proofing.  

 

The old place we had was a steel frame with floors fixed directly onto joists with no attempt at sound proofing anywhere at all and we never noticed it being a problem.  Now we've put up an MBC timber frame - with posi joists and 22mm chipboard nailed and glued above.  I plan to put in engineered wood floors upstairs and was assuming I'd put in acoustic underlay of some sort, rockwool in the floor space and doubled up plasterboard under.    The walls are filled with cellulose - the building's three floors and the stairwell will carry sound pretty well all the way up.  

 

Looking at the underlay options there seem to be many that are thin with not much benefit in terms of noise and then eye wateringly expensive thicker options that offer significant sound reduction.  

 

Any experience from the MBC builds that might help square this particular circle would be much appreciated

 

Oh and as a supplementary the stud walls come with a sheet of 9mm OSB on one side - any idea of how much this contributes to sound reduction?  I was told the other day that there's some advantage in having different weights of covering on each side of the walls to reduce resonance - I couldn't find anything with a bit of googling that gave much on OSB in the wall for sound.

 

 

[jack]

Do whatever you can to reduce noise via the floors, imo.

 

One of the things I'm disappointed by with our build is how bad sound transmission is from the (carpeted) upstairs floors. My noisiest, danciest child has the room immediately above my study and at times it sounds like elephants are being thrown around.

 

If I were doing this again, I'd insist on a screed upstairs rather than relying on chipboard and sound insulation.

 

That said, I'm highly sensitive to noise, and it doesn't really worry my wife. 

[nod]

Res bar on the ceilings with two layers of sound block is one of the most cost eftive ways of achieving a high level of soundproofing 

[Thedreamer]

My plan is to use acoustic isolating strips, acoustic insulation slabs, a good underlay and a carpet for the kids rooms.

 

My five year old boy can be quite noisy.

 

What are the options for insulating a stud wall. We have an open plan partly vaulted ceiling with the kids rooms on either side?

 

 

 

[ToughButterCup]

8 hours ago, nod said:

Res bar on the ceilings with two layers of sound block[...]

 

Que?

[mike2016]

I was talking to MBC about this before and they suggested Celecta Screedboard 28 on the 1st floor. This is a click together system. Planning for that in my house. Also rockwool in between studs on inner walls and between posijoists. I'm planning on using Fermacell 12/15mm everywhere which also helps. I've seen videos of people using a resilient channel, basically a metal strip that you then connect two layers of plasterboard onto to dampen impact noises? My finished floor level upstairs will be +28mm deeper with the approach I'm taking but my stairs etc will be sized to accommodate. Hope this helps...

[jack]

3 hours ago, recoveringacademic said:

Que?

 

Resilient bar

[Jeremy Harris]

I was surprised how big a difference bonding down 12mm thick bamboo with Sikabond 95 adhesive made.  I think the key is that the relatively thick layer of very rubbery Sikabond 95 inadvertently acts as a pretty good sound absorber. 

 

Our first floor make up (except for the bathrooms) is (top to bottom):

 

12mm strand woven T&G bamboo, bonded with

Sikabond 95, to

18mm T&G OSB3, laid on to

253mm high Posijoists, at 400mm centres

150mm acoustic rock wool (a really unpleasant job...)

12mm plasterboard

~3mm plaster skim

 

The bathroom floors are:

 

12mm Travertine stone, laid with Mapei flexible adhesive to

9mm marine ply, glued and screwed to

18mm OSB T&G flooring, laid on to

253mm high posijoists, at 400mm centres

150mm acoustic rockwool

12mm plasterboard

3mm plaster skim

 

Overall we haven't noticed any significant noise transmission at all.  We do have rugs over the bamboo flooring upstairs, and tend not to walk around the house in hard soled shoes, plus we don;t have young kids bouncing around.  However, we have had visitors to the house who wanted to see how good the sound resistance was, so one went and jumped around upstairs whilst the other listened downstairs and the sound transmission wasn't really noticeable to me.

[HerbJ]

We did several things  to mitigate sound/noise transmission in our timberframe house, as follows

1. All of the internal stud walls are 140mm ( unfinished stud width) , giving a more robust feel and space for additional noise insulation.
2. We used sound resistant plasterboard on all walls, except for bathrooms which have moisture resistant plasterboard, and all ceilings.  We used 12.5mm on walls and 15mm on all ceilings
3. We installed sound insulation in all ceiling joists and stud  walls.
4. The design of the stairs required both sides of the stair well (all three floors) to be sheathed in 15mm OSB, to support the structural loads from the stairs, which is a mono-stair. The 15mm OSB was glued and screwed.   We extended this 15mm sheath beyond the main staircase central core, to  all walls forming the key central hub of the house, to assist with soundproofing of all room leading off the hall and landing (particularly bedrooms)) and also to assist with plasterboarding by removing a step on the studs. This was a consequence of the stair design and not something we had planned, but it might be something to consider as it does improve acoustic performance
5. All our bedrooms  except one are separated from each other by  a bathroom,  and /or dressing room . For the other one, it is separated by a wardrobe and a double layer of sound resistant plasterboard
6. We installed a double layer of 15mm sound resistant plasterboard on the plant room ceiling, which is below a bedroom
7. We installed UFH on the 1st floor and installed a specialist product that had a acoustic/heat insulating layer with  20mm of  2E11 Fernacell boards on top - see attachment
8. We installed Cellecta Screedboard 28 on the 2nd Floor - see attachment. It's a good product and easy to install.

3 hours ago, mike2016 said:

I was talking to MBC about this before and they suggested Celecta Screedboard 28 on the 1st floor.

 

The acoustic performance is reasonably good, particularly airborne sound. However, we have engineered floor finishes or porcelain tiles in all 1st Floor rooms and the 2nd Floor landing. The rooms on the 2nd floor are carpeted, except for the shower room. We still have some  impact sound transmission, particularly from the 1st Floor.  In hindsight, I should have gone the extra step/expense  and installed acoustic hangers for the ceiling plasterboard, particularly for the GF ceilings.

 

If you are planning to install Cellecta Board or some other acoustic insulation slabs, remember to take into account for your floor build-up and ceiling height calculations.

 

ECO-10U Pt E.pdf

ScreedBoard_28_Cellecta_Design_and_Installation_Details.pdf

Edited August 22, 2018 by HerbJ
clarification and minor typos

[Mr Punter]

2 hours ago, mike2016 said:

I'm planning on using Fermacell 12/15mm everywhere which also helps.

 

I have used Fermacell in the past and found it very expensive and difficult to cut.  Last job we used Knauf Soundshield Plus plasterboard.  Very tough, good sound and fire resistance, holds a screw OK and is not bad value.

 

17 minutes ago, HerbJ said:

We installed Celecta Screedboard 28 on the 2nd Floor

 

We used this on a conversion and achieved v. good sound test results.

[MikeSharp01]

56 minutes ago, HerbJ said:

140mm

Is that the Stud width or the finished width - assume stud width?

[HerbJ]

3 minutes ago, MikeSharp01 said:

Is that the Stud width or the finished width - assume stud width?

 

Yes the unfinished stud width, rather than the standard 89mm width

[Besidethewye]

Many thanks for all the suggestions - not short of a few options there then!  

 

 

[ragg987]

On our MBC build, I went with their suggested pozi-joists sizes and spacing. Topped with OSB.

 

This is the least satisfactory aspect of our build, the floors bounce quite a bit, the OSB squeaks, and noise transmission to lower is quite high.

 

By contrast, have beam and block floor to the basement, this is great and noise transmission is low.

 

As mentioned above, I would pay better attention of I did it again, maybe screed and a more rigid structure.

[jack]

9 hours ago, ragg987 said:

This is the least satisfactory aspect of our build, the floors bounce quite a bit, the OSB squeaks, and noise transmission to lower is quite high.

 

We have a surprising amount of squeaking in those areas where we didn't get around to screwing down the chipboard. Unfortunately, the main place this happens is our bedroom. Drives me mental.

 

Once I finish the more important stuff I'll be pulling the carpet up and adding some screws to try and reduce it.

 

I'm also a little surprised and disappointed by how bouncy the floors are. Again, this is something that no-one else in the house notices or cares about, but I find it distracting (I'm really easily distracted )

[Jeremy Harris]

The odd thing is we have 18mm OSB on 253mm high Posijoists on 400mm centres, ring nailed down, and there wasn't any noticeable bounce, even before I laid the bonded bamboo.

 

I didn't bother screwing the OSB down, but I did put loads of PVA on it.  Initially I just sealed the OSB with diluted PVA soon after it went down, to make it easier to clean up (makes it a great deal easier to sweep clean during the build, I found) and then I went around and poured nearly neat PVA into all the OSB joints and brushed it in, before sealing it again with diluted PVA a few days before I bonded the flooring down.  Not sure if that helped, but my thinking was that it couldn't hurt to try and glue all the T&G joints a bit.

[jack]

13 minutes ago, JSHarris said:

The odd thing is we have 18mm OSB on 253mm high Posijoists on 400mm centres, ring nailed down, and there wasn't any noticeable bounce, even before I laid the bonded bamboo.

 

How long are your spans though? Our bedroom is the room with the noticeable bounce, and has the longest spans in the house at over 5m (no other room has more than 4m). Also, one end of the joists in only that room sit on a steel that's about 7m long. If you walk past the chest of drawers, the mirror on top wobbles, so it isn't just me!

 

There's some bounce in the other rooms, but it's is definitely worse in our room.

 

Noise transmission is bad everywhere though.

 

[CC45]

400mm rather than 600mm joist spacing eliminates the bounce from what I've observed.  I've glued and screwed 22mm ply either side of the joists on my longest spans - seems to help.

[Jeremy Harris]

The longest unsupported span is around 5m, IIRC, and is in the spare bedroom, where the joists only have one intermediate support about 1.8m in from one end over their just over 7m total span.

[HerbJ]

I don't believe MBC timberframe houses are any more susceptible to noise transmission then any other manufacturer, or even traditionally built houses.   It's a key element of design that  has to be be carefully managed in all house builds and most of the areas to be addressed are identified in the contributions above.  It's an element of the build that requires  more attention and a budget. 

 

Unfortunately, it's an element of the build that nearly most of us failed to recognise as a potential issue, when we were grappling with all the  things that were  of a higher priority at the time.  I had the advantage of seeing a several timberframe builds and did  address some of the design issues, as detailed above, but I could have done more at minimal extra cost and had better performance.  Just like @jack  and others , we have some minor squeaking of the floor in the master bedroom ( though I think it is not a  bouncy floor, but the UFH system I used is a floating system and was not laid, as well as it could have been) and the impact noise transmission is not great ( but luckily, we don't have  teenage children, only occasional  younger grand kids ).

 

 

Edited August 24, 2018 by HerbJ

[jack]

8 hours ago, CC45 said:

400mm rather than 600mm joist spacing eliminates the bounce from what I've observed.  I've glued and screwed 22mm ply either side of the joists on my longest spans - seems to help.

 

I believe all our joists are at 400mm spacing.

[HerbJ]

1 minute ago, jack said:

I believe all our joists are at 400mm spacing

 

Yes, same for us. I also insisted during the final negotiation on the timberframe price that it must be  a 22 mm floor and that it was  glued and screwed, not nailed!  This was after watching @jack wife ordering boxes of decent screws  and carefully screwing down their already installed floor, having decided that there it was too squeaky with just nails.

[jack]

2 minutes ago, HerbJ said:

 

Yes, same for us. I also insisted during the final negotiation on the timberframe price that it must be  a 22 mm floor and that it was  glued and screwed, not nailed!  This was after watching @jack wife ordering boxes of decent screws  and carefully screwing down their already installed floor, having decided that there it was too squeaky with just nails.

 

Yes, what a shame we got distracted before she reached our bedroom! The kids' bedrooms are virtually squeal free!

[CC45]

Ours were just glued.  I screwed them all subsequently - q a bit of time needed and screws werent cheap. Time and money well spent.  Wish we had 400mm centres throughout.

[Weebles]

We were planning on laying carpet (plus underlay) straight onto the OSB.

But the OSB is lifting at the edges due to the house flooding a couple of times in the recent rain.

Any suggestions for:

 

1. Underlay

2. What to do if anything about the slight ridges at the OSB joins now

3. Is laying underlay straight onto the OSB a good plan or not

 

We have only allowed 20mm for first floor finishes, so its a bit late for that Cellecta board.  ?

 

As a result of this thread we will screw down the boards too.  Thanks.