soundproofing floors/ceilings in MBC timber frame

[Jeremy Harris]

Ours swelled a bit at the joints, where water got in to the end via the T&G joints (we also had torrential rain for a day whilst the frame was going up, so everything got soaked).  I just hit it with a belt sander to take the raised bits off,  once it was dry and before I PVA'd the whole lot.

[ProDave]

One thing that annoyed me and I would have changed if I had noticed:

 

Most of our posi joists span end to end of the house in one go. so they are sized for the longest unsupported span which is about 5 metres.  The other shorter spans are therefore over specified.

 

But where the stair well cuts the house in half, the SE in his wisdom decided that in one bedroom, the joists didn't need to be that big, so a few that but up to the stairwell are smaller.  So we have the situation where one end of the bedroom has over sized joists and the other end of the same room has "correct" sized joists.  Needless to say this is the one part of the house where I do notice some floor bounce at that end of the room.

 

Had I noticed this detail, I would have changed it at design time so all joists were the same size, but I did not spot it until it was too late.

[epsilonGreedy]

2 hours ago, ProDave said:

So we have the situation where one end of the bedroom has over sized joists and the other end of the same room has "correct" sized joists.  Needless to say this is the one part of the house where I do notice some floor bounce at that end of the room.

 

 

Erm there is some ambiguity here.

 

Think you are saying that the end of the room with smaller (correctly) sized joists is the only part of the house with noticeable bounce or does the whole room have some bounce?

[Mr Punter]

Most floors are designed to have a maximum 12mm or 0.003 x span (whichever is least) deflection limit.  If you specify that you require maximum 8mm or 0.002 x span (whichever is least) deflection there will be no issues with bouncy floors and the cost difference is fairly small.

[ProDave]

1 hour ago, epsilonGreedy said:

 

Erm there is some ambiguity here.

 

Think you are saying that the end of the room with smaller (correctly) sized joists is the only part of the house with noticeable bounce or does the whole room have some bounce?

Yes the end of the room with "correct" sized joists has noticable bounce, the end of the room with oversized joists does not.  Had I spotted this on the plans, I would have asked for the same over sized joists throughout.

[Mr Punter]

Have a look at https://www.jamesjones.co.uk/interactive-span-table and go for a joist size / spacing where the deflection is less than 8.00.

[vivienz]

The MBC timber frame crew arrived on site this morning and I asked them about squeaky floors.  Interestingly, they said that the manufacturer of the boarding used for the floor, Egger, specifically recommend not to screw the board down as they believe this can increase noise.  Instead, they sparingly use a few nails to hold the boards in place and then glue them down.  I'll check tomorrow what the glue is as I can't remember the name of it now.

[PeterW]

4 minutes ago, vivienz said:

The MBC timber frame crew arrived on site this morning and I asked them about squeaky floors.  Interestingly, they said that the manufacturer of the boarding used for the floor, Egger, specifically recommend not to screw the board down as they believe this can increase noise.  Instead, they sparingly use a few nails to hold the boards in place and then glue them down.  I'll check tomorrow what the glue is as I can't remember the name of it now.

 

Will be Egger D4 foaming polyurethane flue - it’s a white bottle and the only one that Egger certify as part of the floor system. 

[vivienz]

That's the stuff, @PeterW.  I remembered the foaming bit but I didn't pay too much attention to the detail.  I knew I'd forget it.

[Dreadnaught]

14 minutes ago, PeterW said:

Will be Egger D4 foaming polyurethane glue - it’s a white bottle and the only one that Egger certify as part of the floor system. 

 

Yes. Here's a fitting guide for the Egger boards which mentions that glue.

 

https://www.egger.com/get_download/17e6c5ab-960a-4e7d-99ee-c46608c62f3a/Flyer_Advanced_Structural_Flooring_System_Fitting_guide_UK_2017.pdf

 

Note that the only nails recommended are for the first row of boards only, and one nail per joist. No screws mentioned.

Edited August 28, 2018 by Dreadnaught
To add note about 1 row of nails.

[Weebles]

29 minutes ago, Dreadnaught said:

 

Yes. Here's a fitting guide for the Egger boards which mentions that glue.

 

https://www.egger.com/get_download/17e6c5ab-960a-4e7d-99ee-c46608c62f3a/Flyer_Advanced_Structural_Flooring_System_Fitting_guide_UK_2017.pdf

 

Note that the only nails recommended are for the first row of boards only, and one nail per joist. No screws mentioned.

 

Thanks for this.  We weren't on site when the Egger boards were put down but there are some blobs of glue around and I think this explains it.  If this saves us from screwing the boards down then happy days ?

 

15 hours ago, JSHarris said:

Ours swelled a bit at the joints, where water got in to the end via the T&G joints (we also had torrential rain for a day whilst the frame was going up, so everything got soaked).  I just hit it with a belt sander to take the raised bits off,  once it was dry and before I PVA'd the whole lot.

 

Good solution thanks.  Sanding the raised bits off should work.  Might mean another power tool for the collection.  ?

[PeterW]

The Egger glue foams more when it’s wet and I had a bit of rain before the boards went down and the joists were a bit damp. Suffice to say we had glue foaming everywhere ..!! 

[JamesP]

I D4 glued and screwed 22mm Caberdek boards down, all of them. The glue is excellent.  I used solid timbers at 400 centres with the longest being only 4 metres.

I did not use joist hangers as they sit on the ground floor walls. 

Really solid first floor. No squeaks or bounce.

Edited August 29, 2018 by JamesP

[Cpd]

6 hours ago, JamesP said:

 

I D4 glued and screwed 22mm Caberdek boards down, all of them. The glue is excellent.  I used solid timbers at 400 centres with the longest being only 4 metres.

 

That’s the same process I used, 22mm chipboard flooring fully glued and screwed along all joints. I also added “no squeek” silicon along the top of the floor joists (had been given this product as it was out of date!)  still perfectly good. I also put 4 lines of  noggins in (solid wood timbers joists) totally overdid it but I wanted something seriously solid ! I got it. I then proceeded to put up not one.... not two..... but three layers of plaster board...... the first was normal (a mistake on my behalf) the next two were acoustic plasterboard. 3 layers of different density acoustic rock wool went in between the joists and a 50mm air gap below the chipboard flooring. All gaps were meticulously sealed with acoustic sealant as each layer enter up / down.... Still got to put final covering on ! I wanted to create as much separation between. The two floors for both heat tranfer and of course sound tranfer. It’s only a tiny cottage so material costs are much smaller than a “normal size build” whatever that is !  

[Nickfromwales]

16 hours ago, vivienz said:

The MBC timber frame crew arrived on site this morning and I asked them about squeaky floors.  Interestingly, they said that the manufacturer of the boarding used for the floor, Egger, specifically recommend not to screw the board down as they believe this can increase noise.  Instead, they sparingly use a few nails to hold the boards in place and then glue them down.  I'll check tomorrow what the glue is as I can't remember the name of it now.

In a perfect world yes. 

The issue is where the nails are not driven completely home and there is insufficient glue at that point. The squeaky floors that folk recount are where the deck board moves up and down the shank of the nail. 

Thats why where @jack's better half screwed alongside each nail, the boards have pulled down tight to the joist top and the slight movement has been removed, ergo the squeak has gone . 

Glued and 5 screws per joist for me every single day of every week. The floor im doing now 

 

 

Sistered timbers either side for levelling ( retrofit on a turn of the century house ) then 22mm p5 D4 glued and screwed as stated.

 

Then for tiling over, 6mm plywood laid into a bed of neat PVA ( 3mm notched spreader ) and screws in at 120mm centres on the X & Y axis. 

Customer says it's like the ground floor room now which is concrete.

 

@vivienz as you will be having aluminium spreader plates for 1stfloor UFH, a mechanical fix will be mandatory as you'll have little to zero timber > glue > deck surface area to allow that method .  

[Oz07]

@Nickfromwales ok when you're doing a bathroom with 10 boards in. 5 screws on each joist. 35 screws per board might slow the house build down a bit. 

 

I use the egger system with ringshank sparingly never had a squeak

[jack]

12 hours ago, Oz07 said:

@Nickfromwales ok when you're doing a bathroom with 10 boards in. 5 screws on each joist. 35 screws per board might slow the house build down a bit. 

 

I use the egger system with ringshank sparingly never had a squeak

 

Wish we'd heard about the Egger system before doing ours. Knowing how much I've hated the squeaking boards in various places we've lived (the rental place we lived while the build went on was the worst example), I did think about getting MBC to glue to boards down as well as nailing. Unfortunately, by the time I got around to thinking about asking, the flooring was already down!

 

I think we added around 20-25 screws per board, and that took long enough.

 

[PeterW]

17 minutes ago, jack said:

 

Wish we'd heard about the Egger system before doing ours. Knowing how much I've hated the squeaking boards in various places we've lived (the rental place we lived while the build went on was the worst example), I did think about getting MBC to glue to boards down as well as nailing. Unfortunately, by the time I got around to thinking about asking, the flooring was already down!

 

I think we added around 20-25 screws per board, and that took long enough.

 

 

Odd that they didn’t glue anyway as it’s how they create a stressed member using a full surface bond to the top of the joists. I put the odd nail in each board with the Paslode but other than that it’s all glued. I had to make a couple of openings slightly bigger and where it had bonded on it took chunks out of the joist surface as it was pulled up. We also cross boarded an existing floor and lifted it with 3x2 trimmer joists and glued that and I’m amazed how much stronger that feels to the old 22mm chipboard that was just nailed on

[jack]

3 minutes ago, PeterW said:

Odd that they didn’t glue anyway as it’s how they create a stressed member using a full surface bond to the top of the joists. 

I don't know either. My guess is that gluing is slower than just dropping each board in place and running the nailer along it.

 

I'm not at all surprised that glue gives a better result. 

[Mr Punter]

The only downside of gluing with D4 is if you ever need to replace a section of floor - perhaps it got wet and started to rot over time - and you have web style joists, you risk damaging the joist(s) so that it may no longer be structurally OK.

 

Also if you get any on your hands it turns them black and takes a couple of days to come off.

[Oz07]

10 hours ago, Mr Punter said:

The only downside of gluing with D4 is if you ever need to replace a section of floor - perhaps it got wet and started to rot over time - and you have web style joists, you risk damaging the joist(s) so that it may no longer be structurally OK.

 

Also if you get any on your hands it turns them black and takes a couple of days to come off.

multitool from below would sort that

[Fallingditch]

On 28/08/2018 at 10:53, Mr Punter said:

Most floors are designed to have a maximum 12mm or 0.003 x span (whichever is least) deflection limit.  If you specify that you require maximum 8mm or 0.002 x span (whichever is least) deflection there will be no issues with bouncy floors

 

I have similar issues to those mentioned by others.

 

Anyone have any suggestions as to how I can actually measure my deflections?  

 

(We actually used easijoists, with the design specified using the easijoist software. I have asked a rep from the joist suppliers to come out and let me have their opinion. First thing to ascertain is whether the construction has been carried to spec ?   )