Thin stud wall construction - ideas?

[Feltwell]

Here at Feltwell Towers, whilst it's a reasonable size house, the family bathroom is tiny - just too small, it's long and thin, with quite a narrow bath with a loo squeezed into the gap next to it. Narrow, short baths are not a natural match for me - I am neither!

Apart from an external extension to the house, the only possible way to create more room is to borrow some space from our en-suite bathroom to create an L shaped family bathroom - it still won't be huge but it will be much better than it is now, and whilst the en-suite will be a little tight as a result it will still be OK.

However - to do this the wall between them needs taking out and a new stud wall building further over. It has to be a stud wall - it's suspended over the stairs - but it needs to be as thin as possible, as every inch of space in that direction will count in both rooms.

I tend to over-engineer most things, and usually for a stud wall I'd be looking at a frame probably made of 4"x2", so with plasterboard each side a wall of around 5" thick - but this time I want go thinner.

Both sides of this wall will be tiled with a shower on them, so the wall surface will be aquapanel rather than plasterboard. The wall will be about 10' tall x 5' wide - one side fixed to the solid outside brick wall of the house, the other side fixed to an existing stud wall that runs parallel to the outside wall.

Turning studwork round to be thinner side on just doesn't seem right, but I could double up the number of studs - or the other thought I had is to make a steel frame in-situ, I can make an outer frame and weld uprights and noggins into it. I'm just worried about "bounce" in the wall - whatever is done needs to flex as little as possible, whilst also being thin, two opposing priorities! It also has to accommodate pipes and a cable. It won't be load bearing.

Any bright ideas?

 

[a twig]

Steel framework partition?

 

[Feltwell]

I've never been that impressed with the commercial U-channel steel systems that are crimped together, commonly used for office partitions - they do visibly move if pushed. If I was to do steel I was thinking more of using heavier gauge angle or tube and welding it into place.

 

[Me!]

Like you, my default for a stud wall is 4"x2", but due to space restrictions, I have just recently made my thinnest ever stud wall using 63mm x38mm cls timber, and it is absolutely fine. My wall is about 8' high and 6' wide, and even has a doorway through the middle of it which I had major concerns would weaken the structure so much that it would bounce and move, but it isn't a problem.
When choosing the CLS I was very careful to select the best bits, and I tested each in the shop for the amount of flex before buying it. Some lengths are made from much more dense timber than others, and the heaviest will weigh almost double the amount of the lightest ones and it makes a very noticeable difference to the amount they will flex.
I have cables running in my wall, and I was very careful to drill the holes through the centre neutral axis of each timber, and I then stuck the 9.5mm plasterboard on each side using no-nails as well as screwing it on, all to provide extra rigidity.
For your wall which is so much taller than it is wide, I would make the frame with the main timbers running the full width horizontally to get the maximum strength from them, and then with vertical noggins where required.
Mine really has come out much better than I ever thought it would

 

[MikeG]

3x2s should be suitable, which will save you an inch, but do add in lots of noggins. These really do stiffen up a wall. I would also suggest screwing the framing rather than nailing it, because again, this pulls joints up tighter and adds to the stiffness. Don't even think about 4x2s the wrong way around. Too thin, too floppy, and you'll never get a wall that is anything like straight.

 

[88v8]

Two skins of 12mm external-grade ply on a frame of 2x1" oak. That's 2x1" sideways.
Stagger the ply joints each side. Start with an 8ft one side, a 4ft the other. Fasten it well around the perimeter. It will be nice and stiff.
No, it may not be completely flat but as the French say, pffft.

Our bathroom is also too small to accommodate a decent length bath. The sad contrast with the 12 x 15ft room we built onto our previous house grieves me, the large rolltop, the open fire. I love a good soak, but now I don't use the piddly little bath and just have a shower. I hate showers. Alas, I have nowhere feasible to expand. Hehyo.

Ivor

 

[Feltwell]

Thanks everyone for your ideas, some good ones there. Another one I had whilst doing some gardening this morning - always good for thinking - was to go for a combination approach, a timber stud frame but with some steel bar screwed to the side of the centre studs to help stiffen them up.

Ironically Ivor, our last house had a narrow and small bathroom, so when moving we wanted a house with a bigger bathroom. So of course we bought a house with an even smaller and narrower bathroom! It's on the back corner of the house with windows on 2 aspects, with a stairwell on one side and a hallway on the other - so options for change are limited. The only room I can go into is our en-suite (originally a box room) which flys above the stairwell and butts onto the end of the bathroom.

Fortunately the changes can be done without taking any character of the house out. The only pain is the wall to be taken out is structural, I think it supports the joists for the floor above, so I should really be good and get Building Regs approval, which is a pain as then they'll want certificates for electrics and various other things that I'm perfectly capable of doing to the required standard myself!

 

[livias]

The thinnest wall that I ever built was 27mm thick between a bathroom and a loo
12mm ply, 3mm sound insulating sheet, 12mm ply. Thin angle iron to hold it in place around the edge.
It worked just fine both structurally and from a sound insulating point of view
It is true that it was not a large wall - about 8ft by 4ft and it had a shower unit butted up to one side which gave it extra stability

 

[Abi Cott]

My internal walls on the top floor are made of tongue and groove planks nailed to a 1x1 frame at ceiling, floor and the sides with a central horizontal support. They appear to have lasted over 100 years. The 9.5mm plasterboard nailed over them more recently doesn't appear to have altered their structural stability. The largest is about 10' x 8'.

 

[Flyfisher]

I can’t think of better ideas than the previous posts but would just throw in a couple of things to think about - noise and regs.

Stud walls are not very sound-deadening at the best of times and the thinner they are the ‘noisier’ they are likely to be, which may be even more of an issue in a bathroom/en-suite situation.

I quite like Ivor’s suggestion of ply on a thin frame as it has good inherent stiffness, especially if you could stretch to 18mm rather than 12mm. However, I wonder how building regs treat a pure wooden partition wall? Would they still insist on a plasterboard covering? I mention this because we have lots of exposed beams in our new kitchen extension and the BCO initially wanted them covered before he would complete the project sign-off! Being listed, he was persuaded to relent but it could be an issue otherwise.

 

[paulc]

Another vote for 3x2 screwed together. As the walls are going to be tiled, OSB would be a suitable covering - Would give the tile adhesive something to stick to. Filling the voids between the studs with rockwool/fibreglass batts would reduce the amount of noise being transmitted through the wall.

 

[MikeG]

The thinnest wall that I ever built was 27mm thick between a bathroom and a loo
12mm ply, 3mm sound insulating sheet, 12mm ply. Thin angle iron to hold it in place around the edge.
It worked just fine both structurally and from a sound insulating point of view
It is true that it was not a large wall - about 8ft by 4ft and it had a shower unit butted up to one side which gave it extra stability

I'm struggling to think of something 27mm thick as a wall. It feels more like a piece of furniture.