Extension starting soon and I have a question about stud wal

[markblue777]

Hi All,
Starting our house extension soon and although builders are coming in to build it to water tight I will be doing everything else.

I was looking through our drawings and noticed a note that stud walls are to be 4x2 with 400 centres with 12.5mm plasterboard. However, I was going to use 3x2 and 600 centers as I was using 12.5mm plasterboard(from what I have read 600 is fine with 12.5mm plasterboard)

The stud walls are just dividers for space and non-load baring. Is there a specific building reg for the timbers to use or are 3x2's ok (the smaller size timbers give us just that little bit more space and are cheaper by a quid or so for each length).

Looking about online and I cannot find anything that states I need to use 4x2's

Insight would be handy.
Thanks
Mark

 

[Rob Platt]

Governed by height as well. Seem to remember if its 2.400 high it needs 100x50. But I've been out too long to confirm current regs.
HTH
all the best
rob

 

[RobinBHM]

3x2 at 600 centres is a bit mean!

 

[markblue777]

Had a dig about on my councils website and found a pdf that had some info

https://drive.google.com/file/d/0B6NQZpUoehq6Vkl2QWM2amJOSGM/view?usp=drivesdk

Basically I think 3x2 are fine as long as 450 centers but I will go 400 as insulation etc is easier at the size.

I was originally going for 400 but read somewhere 600 is fine for 12mm plasterboard. However, maybe that was for 4x2. Thinking about it 400 would be better on the thinner material.

Cheers
Mark

 

[Doug71]

I would use 4x2 on 400 centres, I did in my house, you only do it once so might as well make a solid job.

I think it's also worth stuffing the cavity with plenty of sound insulation, depending on what the rooms are used for.

Doug

 

[RobinBHM]

Isnt it great that plasterboard is 1200mm sheet size and plywood 1220mm!

-Ive been caught out a few times!

I think 400 centres is better for 3x2

I wouldnt use CLS as thats only about 38mm thick!

 

[markblue777]

Hmm I was going to use CLS as it seems that is what is available everywhere. I will give a couple of local timber yards a call and see what they are have. I thought CLS was the norm now.
Cheers
Mark

 

[Phil Pascoe]

I'd use 4" x 2" on 400 centres. You're only doing it once - better to regret something you have done than something you haven't.

 

[RobinBHM]

Any good timber yards should stock 3x2 studwork which finishes at 70 x 45

CLS sizes are:

3x2 = 63mm x 38mm
4 x 2 =89mm x 38mm

CLS is Canadian Lumber Stock originally made for the Canadian market and becoming popular over here, I guess because it is cheap, but its undersized in reality.

If it was me, Id use 4 x 2 section, 90 x 45 at 400mm centres as Phil suggests. In the scheme of things the difference in cost cant be much at all.

 

[Lons]

As a retired builder who built a lot of stud walls over the years I would always recommend using 4 x 2 ( 100 x 50 ) although unless rough, the timber will come regularised and about 5mm thinner anyway. a 3 x 2 stud wall is just not solid enough imho and far more likely to distort, remember it's carrying a fair load even though vertical. 12mm plasterboard plus a skim on both sides is pretty heavy stuff.

400 centres is also what I'd size at though with 4 x 2 you would get away with 600 if putting in plenty of noggins but in reality it's no more expensive to put in the extra verticals anyway as it is to cut extra noggins. The suggestion given to soundproof is always worth the extra few quid as well as cost is very small at this stage.

Although just partitions at the minute needs might change as they often do and thin walls in future might be a disadvantage.

cheers
Bob

 

[Phil Pascoe]

Don't forget to run all your wiring including any speaker and computer wiring in before you close up.

 

[n0legs]

I do mine with CLS at 400 centres.
Overboard with half inch shuttering ply, screwed on with the boards horizontal.
Rammed full of insulation, then boarded with half inch taper edge plasterboard, then skimmed.
Aquapanel instead of plasterboard in bathrooms/wet areas.

I do it this way as the wall is so much tougher against impact damage, very useful if there's kids about. Its quieter and best of all, except for the heaviest of shelves, you can fix stuff like pictures, mirrors and TV's pretty much anywhere.

 

[markblue777]

Looked at prices and for 75mm x 47mm carcussing timber 3m length it works out about £1 more expensive per length and the is C24 graded as well. So I think I will go with that.

With sound insulation do you just put in 50mm thickness. as the density of the material is what limits the sound so over packing can have an adverse effect, correct?

with regards to aqua panel board. do you use that all around the bathroom or just where water can contact?

I was going to put normal plasterboard around the walls but around where shower is I was going to use moisture resistant plaster board and tile over top (or use a colour perspex over it not sure yet)

Another question, With ceilings does the plaster board need to be fire resistant (pink one) or is normal ok) The ceiling is an outside ceiling as it were.

Cheers
Mark

 

[RobinBHM]

fire resistant plasterboard is usually only needed where protection is needed around steel beams.

Do you mean you are plastering a ceiling that is open to the outside, for example under an overhang or large soffit? I dont if plasterboard would be suitable for that. Maybe it needs a cement board.

 

[markblue777]

I just meant I am plastering on to flat roof joists that's all

 

[Doug71]

As far as I know you can pack in plenty of soundproofing, the denser the better, it's not like thermal insulation that shouldn't be compressed.

People often use moisture resistant plasterboard in bathrooms but something like Hardiebacker around the showers where it will be tiled on.

Ceilings are generally okay with just normal plasterboard.

You are always best having a good chat with the building inspector before you start, regs change all the time and he will tell you exactly what he wants to see.

Doug

 

[markblue777]

Yeah i think that's best. Just trying to get an idea on costs really

Cheers
for all the help guys

 

[RobinBHM]

I just meant I am plastering on to flat roof joists that's all

Ah ok, an internal ceiling but under a flat roof!

normal plasterboard is fine.

Dont go buying the fireproof board unless you need it around steels -1/2" pink plasterboard is really heavy! (and expensive).



soundproofing: packing the void in between the studs will make the wall sound more dead and help cut out any ringing.

I would think any of the roll insulation suitable for lofts would be ideal.

I know you can buy dense rockwall batts for soundproofing so maybe the normal rockwall cavity batss could be used. Im sure though that the cheap fibreglass or equivalent loft rolls are used for filling boxing in soil pipes to deaden sound, so Im sure it would be fine in a studwork wall.

 

[markblue777]

Thanks robin

 

[slate1234]

Are you sure your stud work isn't carrying any weight that's one reason you could have 4x2 stud work on the drawing's, then it does need to at 400 center's, dont forget to double up on the joist's under your stud (some drawings say treble), we alway's use rockwool for sound proofing,
Paul