I've spent the last several years working on residential projects (wood framing), but am now helping out on another project in the office that's using metal studs...
Other than the difference in size, when/where do you use 3-1/2" metal studs vs. 3-5/8" metal studs?
I should know the answer to this, but it' s slipped my mind...
Fred Scharmen
Mar 10, 09 1:39 pm
I'm tagging this to check back later for an answer - I've always wondered the same thing.
AJ&M
May 23, 21 3:26 pm
It has nothing to do with gauge. The difference is 3 5/8 is for commercial use to fit commercial doors such as welded or knockdown bucks where as 3 1/2 inch is used in residential to fit residential door bucks. if u use 3 5/8 in a residential project u either have to use 3/8 gypsum or rip sum 1by lumber to make the residential door jamb flush.
b3tadine[sutures]
May 23, 21 6:49 pm
Imagine dragging a thread, 12 years old, nearly a high school student, and still being wrong.
natematt
May 23, 21 7:15 pm
While clearly not required for frames, wouldn't the basic principle he's pointing out make sense though? You'd use them if you needed them in wood frame construction to simplify integration with 2x4 studs.
Every once and a while it's helpful to throw some metal studs around type 5 construction...
AJ&M
May 23, 21 7:32 pm
So first of all I didn't realize this thread was this old and I apologize, but b3tadline
obviously never worked with these materials or doesn't know how to read the chart he posted 2x4 wood studs plus 1/2 inch gypsum on each side gives you a 4 1/2 wall. the 1/8 difference leaves an ugly gap between the jamb & trim. 3 5/8 studs are designed for commercial door bucks
natematt
May 23, 21 7:52 pm
Commercial frames are designed to fit standard metal framing would probably be more accurate.... Regardless...
He's pointed to an example that you can get frames to fit either one. Is the reference for this diagram a residential door? I don't know. But why would you bother using metal framing in a wood frame structure for door bucks only? And if it's the entire structure, you're probably going to be using commercial door frames anyway, or at least should be?
natematt
May 23, 21 7:58 pm
Also, 1/8" gap with HM frames is pretty typical for construction tolerance. The gyp is overlapped by the frame, so it dosn't make an unsightly gap...
AJ&M
May 23, 21 8:14 pm
you can't get frames to fit either one. the samples in that diagram dont show a residential wood door buck which gives the gypsum a 1/8 reveal & is not acceptable if you are working in luxury homes or condos. that gap has to either be filled with caulk a def no no or you have to rip lumber to fill it still an unsightly alternative. now I would use metal in most rehabs however an example is I am currently working on a basement rehab where I prefer to use metal and building two new closets in the first floor. I will use 3 1/2 metal to frame those closets & line the bucks with 2x4. it will take me 2/3 less time and no mess.
b3tadine[sutures]
May 23, 21 8:25 pm
Actually, I can read. There's specifically detailed information for 5/8" gyp on a 2x4 wall and 5/8" on 3-5/8". It's not an 1/8" it's a 1/16" on either, and if anyone here can tell me that a decent contractor can't make up a 1/16" then get a new gig.
b3tadine[sutures]
May 23, 21 8:29 pm
Besides, if I'm doing a luxury condo, or home, so you really think I'm going to use anything but a fry reglet, trimless door frame? Wood, or metal bucks in those cases is amateurish.
natematt
May 24, 21 12:56 am
I'm going to assume AJ&M is doing more traditional wood door frames with casing. In which case, Yeah it makes sense that you wouldn't do 3 5/8" framing... and if you're using 2x4 framing, 3 5/8" won't be compatible anyway. And yes, 1/8" gap wouldn't make sense, because that's now how that kind of frame is installed.
As I said in the first place, the obvious purpose is to use it when you need/want metal framing to go with standard 2x4 wood framing, which is technically what you are suggesting, but I disagree that that is the specific purpose (door bucks) that they were made for, or that this is something people are primarily using it for. Glad it works well for you!
natematt
May 24, 21 1:10 am
@b3tadline... Had a recent experience doing this on a project where the drywaller could not figure out how to do this for their life. Blew my mind. Had to go on site and physically orient the trim for them....
AJ&M
May 24, 21 1:28 am
my original reasoning was only answering the original question, I didn't mean for this to be a debate one of your responses seemed condescending I apologize for any misunderstanding
A W
Mar 10, 09 2:00 pm
3 1/2" metal studs?
Their availability is limited. I have never seen them.
The usual ones:
1 5/8
2 1/2
3 5/8
4
6
A W
Mar 10, 09 2:02 pm
Dietrich UltraSTEEL®Metal Studs are available in 1-5/8",
2-1/2", 3-1/2"*, 3-5/8", 4", 5-1/2"* and 6" widths or web
depths. Studs are manufactured using the UltraSTEEL®
process. Studs may be spaced at 12", 16" or 24" on-center
based on wall height. Wall height, stud spacing, framing
condition, deflection limitations and lateral load are all fac-
tors that must be considered in determining the correct
size and gauge of the applicable product.
* Available in limited markets Interior
3-5/8" is so you can put a 3-1/2" 2x4 in the steel stud to nail or fasten to. I didnt know there was a 3-1/2" steel stud - that will get confusing. Are they for the home interior market?
AJ&M
May 23, 21 3:21 pm
true you can fit a 2x4 in it but that is not the purpose
binary
Mar 10, 09 2:19 pm
ALSO CHECK THE GAUGE THICKNESSES ON BOTH...
AJ&M
May 23, 21 3:25 pm
It has nothing to do with gauge. The difference is 3 5/8 is for commercial use to fit commercial doors such as welded or knockdown bucks where as 3 1/2 inch is used in residential to fit residential door bucks. if u use 3 5/8 in a residential project u either have to use 3/8 gypsum or rip sum 1by lumber to make the residential door jamb flush.
A W
Mar 10, 09 2:29 pm
Gauge makes all of the difference. That depends on what you're using it for.
3 5/8" is standard. I would stick with it.
evilplatypus
Mar 10, 09 2:41 pm
Maybe it's a heavier ga. exterior framing size - I dont know, Im just depressed its so shitty out, so slow and so quiet in here
sharkswithlasers
Mar 10, 09 3:11 pm
I like to use the 3-1/2 when I need 1/8 less, and vice versa. :-)
pickfirst
Jul 19, 10 5:32 pm
I hope evilplatypus is right, that makes the most sense (blocking etc)...
LOOP!
Jul 19, 10 5:46 pm
I agree w/ Make on this. Just use 3-5/8" unless you have a really good reason. 3-1/2" is uncommon.
If you're using both interchangably on a set of drawings without much justification or consistency, you'll really annoy your contractor and confuse your subs. Then you get to respond to another RFI.
curt clay
Jul 19, 10 6:05 pm
Off the top of my head, this may be due to a few different factors:
- are you attaching drywall to both sides or just one side of the stud? Perhaps the wider stud size coupled with a lower gauge would give you a greater rigidity and allow you to do taller walls?
-US Gypsum board gives stud size / gauge requirements relative to the height you are trying to achieve. If you are doing 12 foot ceilings or higher, perhaps the wider stud width is required?
- Perhaps it is a demising wall where you are trying to reach a specific fire rating and certain types of insulation will fit better within one stud size than the other. Are you insulating the wall?
just a few questions for you to explore when making the determination....
LOOP!
Jul 19, 10 6:30 pm
hmmm, I'd be really surprised if that extra sliver of width gives you much more rigidity but it's possible. You're usually just stuffing batt insulation into the walls, so I doubt it has to do with being able to fit the insulation into the cavity.
I have seen random details here and there w/ the 3-1/2" but it's rare. I'm pretty sure they still meet code. Would be interested to hear if the slight difference in width won't let you get a fire rating. I'd be surprised if that was the case.
snook_dude
Jul 19, 10 6:58 pm
Dudes it is for wood blocking be it framing blocking or fire treated wood blocking. Casing for windows and doors. Makes it a heck of alot easier for attachment of door jambs and window frames. Typical is 25 ga. unless your getting into some unreasonable height or if it is a bearing wall then you might need to kick it up to 18 Ga.
Remember to always have a slip header track and hold the gypsum board back to allow for deflection in the wall or you will end up with one big arshe head ache!
shaner
Jul 19, 10 11:07 pm
whats with the 4" ive never use that either
holz.box
Jul 19, 10 11:44 pm
just be sure to keep them far away from any kind of thermal envelope...
aquapura
Jul 20, 10 9:06 am
Yep, it's for blocking. Wood 2x4 will fit right in there. Haven't any of you worked commercial construction before?
pickfirst
Jul 20, 10 10:42 am
Aquapura, I hate to say it, but this thread certainly has a "stumbling/bumbling" feeling to it! But it also doesn't seem far off from the typical answers I would expect from designers! :)
Don't you know? We're architects, not builders. We simply tell other people how to put something together - without actually knowing how it goes together.
Ah the great irony - telling someone how to swing a hammer without us ever swinging one ourselves...
binary
Jul 20, 10 1:10 pm
and i like when this shit comes up.... because then you really see who has done construction and built, rather than making lines.... just saying...
don't forget to wear gloves when using metal studs, they will slice you right open....
Barry Lehrman
Jul 20, 10 2:14 pm
Only time I've spec'd 3 1/2ers was when creating a UL-rated partition with multiple layers of drywall. but then, we were normally using even smaller studs to keep the wall thickness consistent.
b3tadine[sutures]
Jul 20, 10 3:17 pm
forgive me for asking but, is there a problem with not knowing something?
LOOP!
Jul 20, 10 3:18 pm
platypus addressed the blocking issue near the beginning. No one is debating w/ him.
My question is actually about the fire rating. I almost always see 3-5/8" and just never really questioned it that much. Obviously, the fire rating generally comes down to the layers of DW or if you use alternate materials for insulation, but I haven't had to assemble my own sheet of wall assembly details before and don't know all the details of the code. I imagine a lot of people use office templates and haven't given it the thought it deserves (myself included).
On another note, I think you guys are confusing building w/ designing. You can build and only have a hazy idea of why you're doing something.
b3tadine[sutures]
Jul 20, 10 3:19 pm
i like the idea of using plywood in lieu of blocking, then the whole wall can work for hanging shit.
do2
Jul 20, 10 3:35 pm
3-1/2 metal studs are used for projects that incorporate 2x4 wood framing as well... so it aaall lines up. For blocking with metal studs sometimes its best to use 16 ga sheet metal strapping... thats if you want to use the same trade.
ReflexiveSpace
Jul 20, 10 11:51 pm
What do2 said, but they aren't as easy to find = more expensive. So just pretend like they don't exist for most purposes.
snook_dude
Jul 21, 10 8:48 am
The UL label assemblies are all over the place as far as stud thickness and guage and hourly rating. You can access the UL site online and take a look.
If you dig, you'll find some of the assemblies will not allow you to go lower than 3-5/8" studs, so width does have a bearing on your rating.
If you used a 3-1/2" stud for a couple of the assemblies, I don't think you'd be up the UL standard. That's not to say the 3-1/2 vs. 3-5/8 would have an actual bearing on fire resistance, just sayin' it wouldn't meet the rating cert.
But then all you master builders already knew that, right? By all means, if I'm wrong about this, correct me.
DisplacedArchitect
Jul 21, 10 5:40 pm
good job intotheloop,
i kind of got tired of teaching others, because people just don't appreciate it and they fire you keeping all those people you trained.
LOOP!
Jul 21, 10 6:11 pm
fair enough.
babo
Apr 22, 16 10:02 am
So, then when do you use 2 1/2" vs. 1 5/8"? Would 2 1/2" allow for electrical devices, etc. to be placed on furred wall?
Non Sequitur
Apr 22, 16 10:08 am
Only during a full moon is 1-5/8" studs acceptable.
curtkram
Apr 22, 16 10:12 am
i like 7/8" hat channels.
Non Sequitur
Apr 22, 16 10:18 am
7/8" are the fedoras of the hat family.
curtkram
Apr 22, 16 10:41 am
that's true. they even look good in millimeters.
Non Sequitur
Apr 22, 16 10:45 am
well played.
gruen
Apr 24, 16 9:06 am
I use 7/8 for furring. Can't really get utilities behind them, except light electrical with shallow boxes. Not very useful. 1-5/8" - same thing but now you can have a normal depth electrical box and maybe water lines. 2-1/2" allows small drain lines (up to 2") so you could put a sink in this wall. 3-1/2" are useful if butting up to a wood wall, but not sure when else.
BulgarBlogger
Apr 24, 16 3:55 pm
3 5/8 mtl studs are usually steel; 3 1/2 are usually wood. There are different r values for each material
BulgarBlogger
Apr 24, 16 11:45 pm
Forgot to mention type of construction... Type 5 vs type 2... Combustible vs non-combustible
Peter Normand
May 25, 21 10:03 am
In commercial construction in Chicago we often use the 2-1/2" Studs, especially in partitions between offices with no recessed items like TV screens. Sometimes 3-1/2" are used the 1/8" can add up when you have 50-100 identical offices lined up on a floor plan. The reason is to save a little space while still getting the sound attenuation insulation in and the recessed receptacles. Most door frames in higher end offices that I detailed are not the hollow metal type but aluminum extrusions with a concealed closer in the head and the clients like to have the frames flush with the wall so they can have a wider clear width in the corridor. The little bits of square inches do add up in larger offices and most commercial leases are for 10 years so efficiency does make sense in some cases. Clients don't want to pay rent on the hollow voids in the walls that they can't use. and making those dead spaces as small as possible can get you space that you might be able to allocate for a little bonus like a file area or copy print station.
If you are in a tough spot and the corridors at the end of a row of rooms is not working out start reducing the stud size if the floor to ceiling is not too high and the walls between spaces don't have doors or windows you can reduce the stud size a little and still get the STC rating you need, but try not to have a lot of different studs that are almost the same size on a job as they can end up in the wrong place.
I've spent the last several years working on residential projects (wood framing), but am now helping out on another project in the office that's using metal studs...
Other than the difference in size, when/where do you use 3-1/2" metal studs vs. 3-5/8" metal studs?
I should know the answer to this, but it' s slipped my mind...
I'm tagging this to check back later for an answer - I've always wondered the same thing.
It has nothing to do with gauge. The difference is 3 5/8 is for commercial use to fit commercial doors such as welded or knockdown bucks where as 3 1/2 inch is used in residential to fit residential door bucks. if u use 3 5/8 in a residential project u either have to use 3/8 gypsum or rip sum 1by lumber to make the residential door jamb flush.
Imagine dragging a thread, 12 years old, nearly a high school student, and still being wrong.
While clearly not required for frames, wouldn't the basic principle he's pointing out make sense though? You'd use them if you needed them in wood frame construction to simplify integration with 2x4 studs.
Every once and a while it's helpful to throw some metal studs around type 5 construction...
So first of all I didn't realize this thread was this old and I apologize, but b3tadline
obviously never worked with these materials or doesn't know how to read the chart he posted 2x4 wood studs plus 1/2 inch gypsum on each side gives you a 4 1/2 wall. the 1/8 difference leaves an ugly gap between the jamb & trim. 3 5/8 studs are designed for commercial door bucks
Commercial frames are designed to fit standard metal framing would probably be more accurate.... Regardless...
He's pointed to an example that you can get frames to fit either one. Is the reference for this diagram a residential door? I don't know. But why would you bother using metal framing in a wood frame structure for door bucks only? And if it's the entire structure, you're probably going to be using commercial door frames anyway, or at least should be?
Also, 1/8" gap with HM frames is pretty typical for construction tolerance. The gyp is overlapped by the frame, so it dosn't make an unsightly gap...
you can't get frames to fit either one. the samples in that diagram dont show a residential wood door buck which gives the gypsum a 1/8 reveal & is not acceptable if you are working in luxury homes or condos. that gap has to either be filled with caulk a def no no or you have to rip lumber to fill it still an unsightly alternative. now I would use metal in most rehabs however an example is I am currently working on a basement rehab where I prefer to use metal and building two new closets in the first floor. I will use 3 1/2 metal to frame those closets & line the bucks with 2x4. it will take me 2/3 less time and no mess.
Actually, I can read. There's specifically detailed information for 5/8" gyp on a 2x4 wall and 5/8" on 3-5/8". It's not an 1/8" it's a 1/16" on either, and if anyone here can tell me that a decent contractor can't make up a 1/16" then get a new gig.
Besides, if I'm doing a luxury condo, or home, so you really think I'm going to use anything but a fry reglet, trimless door frame? Wood, or metal bucks in those cases is amateurish.
I'm going to assume AJ&M is doing more traditional wood door frames with casing. In which case, Yeah it makes sense that you wouldn't do 3 5/8" framing... and if you're using 2x4 framing, 3 5/8" won't be compatible anyway. And yes, 1/8" gap wouldn't make sense, because that's now how that kind of frame is installed.
As I said in the first place, the obvious purpose is to use it when you need/want metal framing to go with standard 2x4 wood framing, which is technically what you are suggesting, but I disagree that that is the specific purpose (door bucks) that they were made for, or that this is something people are primarily using it for. Glad it works well for you!
@b3tadline... Had a recent experience doing this on a project where the drywaller could not figure out how to do this for their life. Blew my mind. Had to go on site and physically orient the trim for them....
my original reasoning was only answering the original question, I didn't mean for this to be a debate one of your responses seemed condescending I apologize for any misunderstanding
3 1/2" metal studs?
Their availability is limited. I have never seen them.
The usual ones:
1 5/8
2 1/2
3 5/8
4
6
2-1/2", 3-1/2"*, 3-5/8", 4", 5-1/2"* and 6" widths or web
depths. Studs are manufactured using the UltraSTEEL®
process. Studs may be spaced at 12", 16" or 24" on-center
based on wall height. Wall height, stud spacing, framing
condition, deflection limitations and lateral load are all fac-
tors that must be considered in determining the correct
size and gauge of the applicable product.
* Available in limited markets Interior
http://www.dietrichindustries.com/library/pdf/catalog/Interior_Framing.pdf
3-5/8" is so you can put a 3-1/2" 2x4 in the steel stud to nail or fasten to. I didnt know there was a 3-1/2" steel stud - that will get confusing. Are they for the home interior market?
true you can fit a 2x4 in it but that is not the purpose
ALSO CHECK THE GAUGE THICKNESSES ON BOTH...
It has nothing to do with gauge. The difference is 3 5/8 is for commercial use to fit commercial doors such as welded or knockdown bucks where as 3 1/2 inch is used in residential to fit residential door bucks. if u use 3 5/8 in a residential project u either have to use 3/8 gypsum or rip sum 1by lumber to make the residential door jamb flush.
Gauge makes all of the difference. That depends on what you're using it for.
3 5/8" is standard. I would stick with it.
Maybe it's a heavier ga. exterior framing size - I dont know, Im just depressed its so shitty out, so slow and so quiet in here
I like to use the 3-1/2 when I need 1/8 less, and vice versa. :-)
I hope evilplatypus is right, that makes the most sense (blocking etc)...
I agree w/ Make on this. Just use 3-5/8" unless you have a really good reason. 3-1/2" is uncommon.
If you're using both interchangably on a set of drawings without much justification or consistency, you'll really annoy your contractor and confuse your subs. Then you get to respond to another RFI.
Off the top of my head, this may be due to a few different factors:
- are you attaching drywall to both sides or just one side of the stud? Perhaps the wider stud size coupled with a lower gauge would give you a greater rigidity and allow you to do taller walls?
-US Gypsum board gives stud size / gauge requirements relative to the height you are trying to achieve. If you are doing 12 foot ceilings or higher, perhaps the wider stud width is required?
- Perhaps it is a demising wall where you are trying to reach a specific fire rating and certain types of insulation will fit better within one stud size than the other. Are you insulating the wall?
just a few questions for you to explore when making the determination....
hmmm, I'd be really surprised if that extra sliver of width gives you much more rigidity but it's possible. You're usually just stuffing batt insulation into the walls, so I doubt it has to do with being able to fit the insulation into the cavity.
I have seen random details here and there w/ the 3-1/2" but it's rare. I'm pretty sure they still meet code. Would be interested to hear if the slight difference in width won't let you get a fire rating. I'd be surprised if that was the case.
Dudes it is for wood blocking be it framing blocking or fire treated wood blocking. Casing for windows and doors. Makes it a heck of alot easier for attachment of door jambs and window frames. Typical is 25 ga. unless your getting into some unreasonable height or if it is a bearing wall then you might need to kick it up to 18 Ga.
Remember to always have a slip header track and hold the gypsum board back to allow for deflection in the wall or you will end up with one big arshe head ache!
whats with the 4" ive never use that either
just be sure to keep them far away from any kind of thermal envelope...
Yep, it's for blocking. Wood 2x4 will fit right in there. Haven't any of you worked commercial construction before?
Aquapura, I hate to say it, but this thread certainly has a "stumbling/bumbling" feeling to it! But it also doesn't seem far off from the typical answers I would expect from designers! :)
Don't you know? We're architects, not builders. We simply tell other people how to put something together - without actually knowing how it goes together.
Ah the great irony - telling someone how to swing a hammer without us ever swinging one ourselves...
and i like when this shit comes up.... because then you really see who has done construction and built, rather than making lines.... just saying...
don't forget to wear gloves when using metal studs, they will slice you right open....
Only time I've spec'd 3 1/2ers was when creating a UL-rated partition with multiple layers of drywall. but then, we were normally using even smaller studs to keep the wall thickness consistent.
forgive me for asking but, is there a problem with not knowing something?
platypus addressed the blocking issue near the beginning. No one is debating w/ him.
My question is actually about the fire rating. I almost always see 3-5/8" and just never really questioned it that much. Obviously, the fire rating generally comes down to the layers of DW or if you use alternate materials for insulation, but I haven't had to assemble my own sheet of wall assembly details before and don't know all the details of the code. I imagine a lot of people use office templates and haven't given it the thought it deserves (myself included).
On another note, I think you guys are confusing building w/ designing. You can build and only have a hazy idea of why you're doing something.
i like the idea of using plywood in lieu of blocking, then the whole wall can work for hanging shit.
3-1/2 metal studs are used for projects that incorporate 2x4 wood framing as well... so it aaall lines up. For blocking with metal studs sometimes its best to use 16 ga sheet metal strapping... thats if you want to use the same trade.
What do2 said, but they aren't as easy to find = more expensive. So just pretend like they don't exist for most purposes.
The UL label assemblies are all over the place as far as stud thickness and guage and hourly rating. You can access the UL site online and take a look.
Here's the link for the UL directory: http://tinyurl.com/2959lgk
Here's the UL main fire resistance page: http://tinyurl.com/29jcmd5
Here's a more explicit how-to: http://tinyurl.com/23vwczg
Overview of rated systems: http://tinyurl.com/dgnjd
And finally, actual rated designs for stud walls:
http://tinyurl.com/2fauoo9
If you dig, you'll find some of the assemblies will not allow you to go lower than 3-5/8" studs, so width does have a bearing on your rating.
If you used a 3-1/2" stud for a couple of the assemblies, I don't think you'd be up the UL standard. That's not to say the 3-1/2 vs. 3-5/8 would have an actual bearing on fire resistance, just sayin' it wouldn't meet the rating cert.
But then all you master builders already knew that, right? By all means, if I'm wrong about this, correct me.
good job intotheloop,
i kind of got tired of teaching others, because people just don't appreciate it and they fire you keeping all those people you trained.
fair enough.
So, then when do you use 2 1/2" vs. 1 5/8"? Would 2 1/2" allow for electrical devices, etc. to be placed on furred wall?
Only during a full moon is 1-5/8" studs acceptable.
i like 7/8" hat channels.
7/8" are the fedoras of the hat family.
that's true. they even look good in millimeters.
well played.
I use 7/8 for furring. Can't really get utilities behind them, except light electrical with shallow boxes. Not very useful. 1-5/8" - same thing but now you can have a normal depth electrical box and maybe water lines. 2-1/2" allows small drain lines (up to 2") so you could put a sink in this wall. 3-1/2" are useful if butting up to a wood wall, but not sure when else.
3 5/8 mtl studs are usually steel; 3 1/2 are usually wood. There are different r values for each material
Forgot to mention type of construction... Type 5 vs type 2... Combustible vs non-combustible
In commercial construction in Chicago we often use the 2-1/2" Studs, especially in partitions between offices with no recessed items like TV screens. Sometimes 3-1/2" are used the 1/8" can add up when you have 50-100 identical offices lined up on a floor plan. The reason is to save a little space while still getting the sound attenuation insulation in and the recessed receptacles. Most door frames in higher end offices that I detailed are not the hollow metal type but aluminum extrusions with a concealed closer in the head and the clients like to have the frames flush with the wall so they can have a wider clear width in the corridor. The little bits of square inches do add up in larger offices and most commercial leases are for 10 years so efficiency does make sense in some cases. Clients don't want to pay rent on the hollow voids in the walls that they can't use. and making those dead spaces as small as possible can get you space that you might be able to allocate for a little bonus like a file area or copy print station.
If you are in a tough spot and the corridors at the end of a row of rooms is not working out start reducing the stud size if the floor to ceiling is not too high and the walls between spaces don't have doors or windows you can reduce the stud size a little and still get the STC rating you need, but try not to have a lot of different studs that are almost the same size on a job as they can end up in the wrong place.
Over and OUT
Peter N