Construction question: Studs on outside of outer leaf?

Hi there. Thanks for all the effort put into this site. I've been through the stickys, a fair share of the threads and I've read Gervais book (great book, saved me from the "making a floating wooden floor on a wooden deck"- trap, among other things) cover to to cover. But still I don't seem to find an answer to my question: I intend to build a two leaf room within a room, each leaf having its own set of studs. Is there anything the matter with placing one of the sets of studs on the outside of the outer leaf (other than taking up potential studio-space)? Placing the studs facing (but not attached to) the original wall would make the actual construction so much easier. I hope you can picture what I mean. Yours sincerely Jan

Since nobody has answered: is it unclear what I mean - doesn't anyone have the answer - is the answer to a similar question posted elsewhere? If so, could anyone show me the thread? Sincerely

When doing that the space between leaves will be smaller. Smaller size means less isolation. Making a 2 leaf construction within an existing construction will atleast create a 3-leaf construction. I'd consider on adding the same mass as the 2 leafs on just one leaf. It'll make your build easier too 8)

Thank you for the input. Yes, it would make it very much easier. Should I leave the existing wall as it is or mount fibergypsum and Rockwoll on it as well. Or is it more cost-effective to place all the fibergypsum on inner leaf? I intend to use Fermacell fibergypsum, 18mm, which has a weight of 21kg/sq.metre. Original plan was to have one layer on each leaf, which would, by weight, be equal to 2,3 sheets of 13mm standard gypsum sheet.

gadunk wrote:

Should I leave the existing wall as it is or mount fibergypsum and Rockwoll on it as well. Or is it more cost-effective to place all the fibergypsum on inner leaf?

yeah sure, also beef up your existing wall with MDF, GB or whatever you like (but don't create an extra leaf, mount it directly on the existing wall) The rock/glass-wool is for absorption in the cavity, filling the whole cavity is no problem. But it's easier to just fill the frame and leave an airspace.

I intend to use Fermacell fibergypsum, 18mm, which has a weight of 21kg/sq.metre. Original plan was to have one layer on each leaf, which would, by weight, be equal to 2,3 sheets of 13mm standard gypsum sheet.

That's some heavy stuff, about twice as heavy as general gypsum. BUT isnt that fermacell stuff 2 layers of gypsum with compressed wool sandwiched in between? (I've seen that stuff and indeed the panels are heavy) That would explain why they are twice as heavy as general GB. If so, then NOPE. It's expansive, will prolly create another leave and is shitty to construct. advise is to use proven stuff like normal GB.

Thanks again. Fermacell is not a sandwiched product. I is sort of gypsum and paperfibre compressed. It looks like GB, but is much heavier and stronger. Can be used as floor as well. Very impact-resistant. You can also hang shelves on it directly. Made in Germany. A similar product, Rigidur, is made in scandinavia. They cost aprox. twice as much as ordinary GB pr sq.meter. I'm told that studios in Denmark are using them now, because they take up less space and are very impact-resistant. This is beginning to sound like an ad, I'm not in any way affilliated etc... You can read about it on www.xella.de.