Gauge for metal studs (Construction of a darkroom)

[Shinnya]

Hi,

I was wondering if anyone has a knowledge of construction, and could answer my question.

I am about to start building somewhat larger darkroom in my new building. This is a shared darkroom where we offer classes/workshops and rent out.

Temporarily, I have about 6-700 sq ft. space, and I am building about 13x20 ft room in the space. It is essentially a box in the space. It has its own ceiling at about 9ft high (ceiling height of the building is 14ft). This room is going to be divided into two separate darkrooms with 5 enlargers in each room.

My question is about the materials for framing. I have been using 2x4 metal studs for the outer walls so far (the building is built with bricks). They are light gauge like 25. I want to find out if I need to use a higher gauge studs for the room since it is going to be load-bearing with its own ceiling. I do not think there will be anything on top of the ceiling, but I would assume it has to carry itw own ceiling drywalls.

Does anyone do building for living and can answer my question? Let me know. Thanks in advance.

Warmly,
Tsuyoshi

 

[Konical]

Good Afternoon, Tsuyoshi,

I don't have any particular expertise in this area, but I wonder if you might ever be wall-mounting any of the enlargers. In that case, I'd certainly want to be sure that the walls are beyond-the-normal sturdy.

Konical

 

[Shinnya]

Hi Konical,

Thank you for your suggestion.

Since this is a temporary space, I will not probably wall-mount the enlargers. This space will eventually come down...

My building is rather big (5500 sq ft), but I cannot finance all the construction right now. When I build the permanent darkroom spaces, I may consider wall-mounting though.

Warmly,
Tsuyoshi

 

[resummerfield]

26 ga steel studs, placed vertically, will support a ceiling of drywall. The wall behind my enlarger is 12 feet, so I used the heavier 20 ga steel studs and placed 2 levels of cross bracing between those studs, for those concerns Konical mentioned. Still, there was too much vibration to wall mount the enlarger. The cost difference of 20 vs. 26 ga steel studs will not be that great, and the heavier studs will make a much nicer wall.

 

[donbga]

Hi,

I was wondering if anyone has a knowledge of construction, and could answer my question.

I am about to start building somewhat larger darkroom in my new building. This is a shared darkroom where we offer classes/workshops and rent out.

Temporarily, I have about 6-700 sq ft. space, and I am building about 13x20 ft room in the space. It is essentially a box in the space. It has its own ceiling at about 9ft high (ceiling height of the building is 14ft). This room is going to be divided into two separate darkrooms with 5 enlargers in each room.

My question is about the materials for framing. I have been using 2x4 metal studs for the outer walls so far (the building is built with bricks). They are light gauge like 25. I want to find out if I need to use a higher gauge studs for the room since it is going to be load-bearing with its own ceiling. I do not think there will be anything on top of the ceiling, but I would assume it has to carry itw own ceiling drywalls.

Does anyone do building for living and can answer my question? Let me know. Thanks in advance.

Warmly,
Tsuyoshi

Tsuyoshi,

Standard guage steel studs will work just fine. If I understand your description the ceiling studs are really not going to be load bearing, rather they will serve as ceiling joists on which you need to hang sheetrock, not bear the load on the building structure from above. If you can get 16 ft. steel 2x4s then you should have no concerns. You may need to attach stiffeners to the joist perpendicular to the direction of the joists. I would do this whether I was using steel or wood. For this, wood 1x4s will work fine.

OTOH, if you need to join shorter studs in the center of the ceiling span to reach the needed joist length you may want to use wood 2x6s instead. In any case I would build the walls and ceiling frame on 16 inch centers rather than 24 inch centers. Your structure should be plenty robust with good lateral support for sheet rocking. Using 24 inch centers tends to make the sheet rock wavy.

 

[Shinnya]

Thanks, everyone.

That is correct that the ceiling of the room is there to carry sheetrock.

So as long as I frame 16" OC, I can use those light gauge metal studs provided that there is nothing on top of the room? Then, looks like I do not have to buy any more studs to build this room. That is great!

I will check if the cost of 20 ga is not that different or not. My assumption was that it will be somewhat different since I cannot buy them at HomeDepot readily. I will look into that regardless.

When people say a wall is load-bearing, it means that it assumes to carry the weight of structure above? What if I put a HVAC unit on top of the room? Now I have to use the higher gauge to support the weight, I suppose?

I have been a contractor by necessity for the last two years...

Warmly,
Tsuyoshi

 

[donbga]

Thanks, everyone.

That is correct that the ceiling of the room is there to carry sheetrock.

So as long as I frame 16" OC, I can use those light gauge metal studs provided that there is nothing on top of the room? Then, looks like I do not have to buy any more studs to build this room. That is great!

I will check if the cost of 20 ga is not that different or not. My assumption was that it will be somewhat different since I cannot buy them at HomeDepot readily. I will look into that regardless.

When people say a wall is load-bearing, it means that it assumes to carry the weight of structure above? What if I put a HVAC unit on top of the room? Now I have to use the higher gauge to support the weight, I suppose?

I have been a contractor by necessity for the last two years...

Warmly,
Tsuyoshi

I would avoid placing an HVAC unit on the ceiling. This will induce vibrations into the structure which at the very least may cause enlargers to vibrate. You may want to suspend the unit from steel roof joists above or mount the unit on the floor. Whether or not the metal studs could reliably carry the load is unknown to me.

To bear the weight of a HVAC unit may require the use of 18 guage steel. Also I would suggest the use of pressure treated wood on the concrete flooring for the plate of the steel partitions to sit on. This will reduce the possibility of rust damage to the steel bootom plate that would normally be touching the floor.

There is information online that covers good/approved construction practices with steel.

 

[Shinnya]

Don,

I thought of the vibration issue. I may have to hang the unit form the ceiling of the building. I am just trying to come up with the best possible solution to this right now.

I was going to place tarpaper underneath the bottom plate. I would think the moisture will rust the metal plate as the building has a concrete floor like you mention.

I still need to figure out the exhaust system and placement of lighting fixtures and switches... I will try to post the drawing of the space soon. Any suggestion is welcome.

Thank you again.

Warmly,
Tsuyoshi

I would avoid placing an HVAC unit on the ceiling. This will induce vibrations into the structure which at the very least may cause enlargers to vibrate. You may want to suspend the unit from steel roof joists above or mount the unit on the floor.

 

[RGyori]

Hello Tsuyoshi,

I am an architect during days (many nights as well!) and thus cannot resist the temptation to make a few suggestions. First of all, since your walls will not have unbraced height* of more than 9 feet, the use of 3 5/8" x 25 gauge steel studs @ 16" o.c. is more than enough. Using 24" centers would also work IF you use 5/8" sheet rock.

*Assumes that the studs are continuous to the underside of the structure above and braced by the horizontal ceiling framing.

I agree that going to 20 gauge is better as it will give you a stiffer, flatter wall. Adding a layer of 3/4" plywood between the studs and sheet rock on the wall supporting the enlargers will go a long way towards eliminating flex and vibration. The lack of mass in normal steel stud construction is also a contributor to sound transmission problems so I suggest adding an additional layer of sheet rock to each side of the dividing wall and make certain to caulk the entire perimeter of the wall/floor junction as well. Sound behaves much like light, so if you can see a gap, sound will travel though it.

Assuming that the ceiling spans the 10 foot dimension of each of the two rooms you must use deeper horizontal members than in the walls. I'd say at least 6" deep. A way around this is to use the wall studs as horizontally framing that is spaced in exact alignment with the wall studs, and support them at mid-span with #10 wire attached to the underside of the structure above. This would give you very stiff and flat ceiling that also would easily support the weight of sheet rock, lights, exhaust fans, electrcial conduits and boxes, etc.. Alternatively the ceiling framing could be attached to the underside of the structure above using spare wall studs cut to length and used as "hangers". Not knowing the material of the floor underside above I can't say which would work best.

Some of the hanging work requires special tools so it might be best to use an experienced tradesman for the overhead work.

Good luck with your project!

Bob

 

[Shinnya]

Bob,

Thanks for your expertise on this.

My concern right now is really to get it done in two months. Since this is a temporary darkroom as I move into the new building, it just needs to be functional for now. So, adding plywood or using higher gauge is not a quite option unless that is the only way I have to do it. Plus, I have loads of lighter gauge studs already...

And I have to say that this room will have to come down eventually as the permanent space is getting built. My question is always how eventual this is going to be...

Anyhow, I am trying to understand what you are saying here but it is a rather difficult language for me. The ceiling of the room spans the 10 ft dimension as you say (or at least that was what I was envisioning) as the divided room is 13'x10'. I would assume you are talking about how the ceiling should be framed. Is there any image I can take a look at of what you are describing?

By the way, floor joists of this building is 3x12 at 12" OC! (2 story building, and span is about 19') It was meant to carry some machinery, I suppose.

If you are interested, you can see 3D rendering by a link below. It is a heavy file by the way (15mb):

http://www.projectbasho.org/1305G/3dmodel_01.mov

Thanks again.

Warmly,
Tsuyoshi

Assuming that the ceiling spans the 10 foot dimension of each of the two rooms you must use deeper horizontal members than in the walls. I'd say at least 6" deep. A way around this is to use the wall studs as horizontally framing that is spaced in exact alignment with the wall studs, and support them at mid-span with #10 wire attached to the underside of the structure above. This would give you very stiff and flat ceiling that also would easily support the weight of sheet rock, lights, exhaust fans, electrcial conduits and boxes, etc..

 

[Dave Parker]

Have your consulted with your local building dept, they often times will have engineers on staff that help with this type of question on how to engineer correctly for several different uses, also it sounds like a project of this size would require a building permit and possibly an on site inspection...I know none of us like government intervention, but in this case is sounds like it could be a good thing.

Dave

 

[Shinnya]

Dave,

I do have a building permit and all those paper work done already. I spent 8 months with the city on that a year before.

In fact, I did have an architect for this project as well. Though I am not quite happy with the service after all... That is a part of the problem. I also had a contractor but had to let him go... That is why I became a contractor by necessity for the last two years.

Right now, I am running the construction site with a couple of crews and some sub-contractors. My carpenter cannot join us for another week or so. That is why I am about to start it by myself.

Thanks for your suggestion though.

Warmly,
Tsuyoshi

Have your consulted with your local building dept, they often times will have engineers on staff that help with this type of question on how to engineer correctly for several different uses, also it sounds like a project of this size would require a building permit and possibly an on site inspection...I know none of us like government intervention, but in this case is sounds like it could be a good thing.

Dave

 

[noseoil]

Tsuyoshi, sounds like quite a project. There is a plastic foam material we provide for our framers, which comes in rolls cut into 3 1/2" or 5 1/2" strips. It lays between the bottom plate and the floor surface (in your case, the existing deck). It would help to make a good seal, reduce sound transmission and vibrations. The advice about hanging the AC unit and ceiling by wires is a good one. This would certainly help to stiffen the lid on the room. Wherever possible, put in enough wires to distribute the loads over more than one member. This will spread out the load and give things a more even strain in general.

Just by way of information, a bearing wall is a wall which supports the structure of a building. It is designed to carry a load from one part of the building down into the foundation. Since you are just putting in partition walls, there really isn't much of a load which you would need to be concerned with, other than the cosmetic, light and mechanical items which will hang directly from the ceiling (as has been mentioned, lights, fans, ducts, sheet rock, insulation, etc.)

At work we build roof trusses. One important consideration we have to watch in the design process is the direction and amount of load which travels through our roof system to walls and into the foundation. A job I looked at today has a 40' long girder truss which carries a 7,400 pound concentrated load (another girder truss) at its center, sits on top of a framed wall, and pushes down on the floor (and I hope not through, the floor). This is a case where we hope the foundation was designed properly, steel was placed properly and walls are framed in the correct manner. A building is a system, in which all parts work in harmony. Best, tim

 

[Shinnya]

Tim,

Thank you for your encouragement.

I got into this project precisely because I did not know what a project like this actually entails. I just simply wanted to have a space where people who are interested in photography can learn and practice. I had no practical consideration other than paying the mortgage!

But I have finished the 2nd floor which is an apartment part so far. I literally did not know anything about the construction when I started this project. I did not speak the language of builders at all, not to mention that English is not my language. With help of others, I have managed to come this far though admittedly it took a much longer time. We will see how the rest will go.

So a member means a "joist"? My floor is concrete slab of 4-5". The building is only 20' wide but 150' deep. It is still massive for me.

Warmly,
Tsuyoshi

 

[RGyori]

Hello Tsuyoshi,

Attached is a quick representation of a simple ceiling framing solution. The view is from above. The wall studs are gray, the ceiling framing members are red and the bracing/suspension system are in yellow. I hope the illustration is clear.

Bob

 

[Shinnya]

Bob,

This is great! Thanks for the clarification though.

I am not sure if you have seen 3d model or not, but I would like to leave to space between ceiling of the floor and room rather open. It is a way to make the space bigger that what it is.

I am going to simply frame the ceiling on top of the wall studs. Anyhow, this is the drawing that I came up with so far. I am doing it on computer now... All the doors are missing from is as of now.

http://www.projectbasho.org/1305G/drawing01_ap06.gif

Thanks for your time and expertise. I really appreciate it.

Warmly,
Tsuyoshi

Hello Tsuyoshi,

Attached is a quick representation of a simple ceiling framing solution. The view is from above. The wall studs are gray, the ceiling framing members are red and the bracing/suspension system are in yellow. I hope the illustration is clear.

Bob

 

[resummerfield]

Hello Tsuyoshi,

If I understand your drawing correctly, you are planning to span the ceiling across the sinks (left to right) with 26 ga 2x4 studs, which would be an unsupported span (between the sink and counter top) of about 10 feet (on each side). I understood Bob to say that a 2x4 “C” stud will not carry a ceiling load (drywall, lights, etc) and span a 10 foot horizontal space without a support in mid-span, either from below (a post, which you do not want), or from above (a wire or hanger as Bob suggested). I agree with Bob, but in reading your subsequent posts I fear that you may not have fully understood him.

 

[Shinnya]

Eric,

Now since you spelled it out that I did not understand what Bob said in the first place, I think I understand what Bob was saying about the framing of ceiling.

He is saying that I need at least 2x6" to frame the ceiling if unsupported ceiling span is 10' from over sink to countertop in each room. Am I understanding it right now?

I suppose I could hang the ceiling since this is a temporary space anyhow. Then, I do not have to order 2x6 studs now... Never thought of that.

I just do not use the language of builders/architects, so "depth" that Bob was referring did not quite register with what is in my head...

I will try to take pictures of the space soon. Thanks again.

Warmly,
Tsuyoshi

Hello Tsuyoshi,

If I understand your drawing correctly, you are planning to span the ceiling across the sinks (left to right) with 26 ga 2x4 studs, which would be an unsupported span (between the sink and counter top) of about 10 feet (on each side). I understood Bob to say that a 2x4 “C” stud will not carry a ceiling load (drywall, lights, etc) and span a 10 foot horizontal space without a support in mid-span, either from below (a post, which you do not want), or from above (a wire or hanger as Bob suggested). I agree with Bob, but in reading your subsequent posts I fear that you may not have fully understood him.

 

[noseoil]

"So a member means a "joist"... yes, but it could be any part of the building. A lot of its meaning is due to the context in which it is used. tim

P.S. Your command of language is very good. It is difficult to communicate in a "foreign language" that being construction.

 

[Shinnya]

Bob,

Now I think understand your original post, I can think though your suggestion.

The suspension is great since I can use the 2x4 that I already have. The only problem is that I have to frame the entire ceiling of the floor to create a firewall. Since upstairs is residential unit while downstairs is commercial, this is what I have to do.

So, I would assume that I have to use 2x6 studs to frame the ceiling of the darkroom. What gauge can I use for 2x6 if the span is 10'?

Thanks again everyone.

Warmly,
Tsuyoshi

Hello Tsuyoshi,

Attached is a quick representation of a simple ceiling framing solution. The view is from above. The wall studs are gray, the ceiling framing members are red and the bracing/suspension system are in yellow. I hope the illustration is clear.

Bob

 

[resummerfield]

......The only problem is that I have to frame the entire ceiling of the floor to create a firewall. Since upstairs is residential unit while downstairs is commercial, this is what I have to do.......

It would be wise to check the specifics of that firewall. In my limited building experience, we needed 5/8 drywall for fire ratings.

 

[Shinnya]

Eric,

Yes, 5/8 is required for the ceiling. That is according to the plan. It is going to be fun job...

Warmly,
Tsuyoshi

It would be wise to check the specifics of that firewall. In my limited building experience, we needed 5/8 drywall for fire ratings.

 

[RGyori]

Tsyoshi,

First of all let me apologize for using industry terminology so freely, it's an occupational habit. I'll try and keep it in mind as I continue...

To make sure I understand your most recent statements correctly, let me ask the following questions:

1. Is the fire separation you refer to is for the floor overhead? (you referred to it earlier as exposed 3x12's @ 12" oc).

2. Do you know what fire rating this separation has to be? It is usually referred to as a "1-hour" or "2-hour" rating.

If the building is a stucture with masonary side walls and wood floor framing and 3 stories or less then a 1-hr horizontal fire separation can be achieved by applying a single layer of 5/8" Type-X gypsum board to the underside of the existing floor joists. A 2-hour separation would require 2 layers. Your wonderful movie showed a stair between the first and second floors. Any such stair would have to be enclosed with 1-hour or 2-hour walls. Any door in such rated walls would have to be fire-rated as well (1-hour wall requires a 45 minute door/frame and a 2-hour wall requires a 90 minute door/frame assembly).

Now with all this aside, the idea of framing the darkroom walls with studs that do not extend all the way up to the previously mentioned upper floor (ceiling) above does make it all the more important that these walls be 20 gauge (ceiling framing too) and be properly braced. By "braced" I mean that the design must resisit the tendancy of partial height walls to sway from side to side.

I saw your preliminary floor plan and it would be helpful to know how it relates to the existing side walls of the building. Some dimensions would be helpful as well.

I'm happy to help but I do need more information. ;-).

Bob

 

[Shinnya]

Bob,

No need for an apology. I certainly understand it. Regardless, I sincerely thank you for your help. I mean I really appreciate it.

I wish I could show you the drawing. Maybe I can try to get it in PDF from my architects.

I do understand about the staircase to be firewalled and any doors in-between to be firerated. I am pretty sure that it needs to be 2-hr rated. A layer of 5/8 sheetrock on the ceiling of 1st FL is indicated on the drawing. Does the combination of a layer of 5/8 sheetrock on on the ceiling of 1st FL and a layer of 3/4 subfloor on 2nd FL create a 2-hr firewall? Anyhow that is how it is indicated on the drawing form the architects.

Just to give you an idea, the building is 20' wide and 150' deep on the first floor. On the second floor, 75' from the front is where the apartment is located. Also, we built an addition on the back part of the second floor (50' from the back of the building) which is going to be a part of business. This is the part where you saw the staircase going up in the 3D rendering. The front 2nd floor is supported by those massive 3x12 @ 12" OC.

So, you are saying that if the walls of the darkroom does not go all the up to the ceiling of 1st FL, it needs to be 20GA as well as the ceiling of the darkroom (which needs to be at least 2x6 as you mentioned earlier).

The only think I can add to the situation which may not be so clear from my drawing is that the room is attached to the perimeter wall which goes all the way to the ceiling. Does it make any difference? Do I still need to go with 20GA?

Also, in relation to this, what I was thinking while I was going through all of these was that why not use wood studs? I just thought that was much simpler answer. Can I do that?

I will try to get some measurements tomorrow with more complete version of drawing and some pictures of the space.

The complication of the project here is that this is temporary space which is going to come down later. But I do want to make sure whatever I do now makes a sense for the later part of the project such as use of space, cost and recyclablity of the materials that I use.

I am meeting my carpenter tomorrow at the site...

Warmly,
Tsuyoshi

 

[RGyori]

Tsuyoshi,

Just a quick note. I was unaware that you have architects already involved in the building. Are they also working on the darkroom project with you? I am compelled to be careful in such matters... professional courtesy and potential legal implications!

Please clarify your contractual relationship with the architects.

Thanks,

Bob