Stud Walls

[Judith Birkett]

Hello

I am having an extension built and am having a stud wall placed in part of it to segregate a room.

I have a few questions if I may. (see attached drawings)

1. The architect has specified 75mm by 50mm stud wall with 75mm rockwool sound insulation. One of the rooms is to be a bathroom, is this stud wall thick enough to deaden the sound of someone in the bathroom?

2. The horizontal noggins in the stud wall are at 450 centres, seems like a lot to me ‘overkill’ do I need noggins that closely spaced. My architect said you could split them into thirds, but its better to be ‘safe than sorry’.

3. The stud wall sole plate sits directly on the screed of the solid floor as oppose to the concrete slab under it, is that ok?

4. As you can see from the attached image, the head plate of the stud wall is attached directly to the underside of the rafter (or noggin) and has been cut to fit. (is it ok to cut head plate?) Is this an acceptable way to do this? My builder has said that I don’t need to connect the head plate directly to the rafter or noggin and that I can leave the dry lined insulation board between them and just connect to that and screw through to the joist/ noggin. My architect said this would lead to instability and is not recommended as you want a solid structure as possible. Any thoughts?

5. The top of the stud wall (head plate) is not parallel with any rafters, it lies fairly evenly between where the rafters would be in the parallel direction. Can I have a stud wall between rafters in the parallel direction? My architect said that’s fine as long a I place a number of noggins between the rafters so that I have something to fix the head plate of the stud wall to.

 

[oldbutnotdead]

1 Won't silence it entirely but should reduce levels acceptably. It'll help if the toilet isn't fixed to that wall
2 In 3 x 2, nogging at 450 centres does sound a tad over the top (what centres are the verticals on?)- but it will give you a very stiff wall, which is handy if you're going to tile it. (NB If you are tiling, consider cement based backing board rather than plasterboard, it is denser so will reduce noise transmission more effectively )
3 Yes as long as the fixings go through the screed and far enough into the concrete to get a solid purchase
4 (Not seen image- not opening a random PDF. Upload it as a jpeg). Architect is correct- you'll get a more solid fix timber to timber than with some insulation in the way (which will compress as you screw the timber to it/over time and potentially give you some movement in the wall)
5 Same question as 4- nog between the joists/rafters then fix directly to noggins.

 

[Judith Birkett]

Thanks oldbutnotdead

really helpful, have uploaded picture as JPEG as well.

Many thanks

 

[noseall]

1. The architect has specified 75mm by 50mm stud wall with 75mm rockwool sound insulation. One of the rooms is to be a bathroom, is this stud wall thick enough to deaden the sound of someone in the bathroom?

If sound deadening was your priority, you could always add the next width size door casing up (swap from 4 1/4" up to 5 1/4") and double up the plasterboards for super duper sound deadening.

There rest of your queries - ask the architect if he is speccing a stud wall or a bomb shelter. Fix to the screed and a few noggs betwixt rafters is fine. Perhaps he thinks you are going to glue it together with Pritt rather than screw it.

 

[Judith Birkett]

Haha, thanks noseall,

 

[flameport]

With regards to the sound, the weakest point (as in where most sound will be transferred between the rooms) is the door - it will be much thinner and lighter than the wall and any gap around/below it when closed will transfer far more sound than the wall ever will.

 

[JohnD]

A fire door is thick and heavy, and very good at muffling noise. You aren't obliged to have one on a bathroom, but compared to a modern hardboard door, it will make a big difference.