The dreaded Span question

[groberts4444]

Hello Forum-ers. I am new here but did not know something like this forum existed and now that I do... I will be using and contributing a lot! I have built multiple smaller garages and even a large metal building, but I am trying to take on a new challenge and was hoping to get some help.

As a disclaimer..... I know that none of the information I receive should be taken as gospel and everything should be run by an architect. I am simply looking for ideas.

The building is going to be 32x48 with a garage/workshop on the first floor as well as a small kitchen interior space, with a bathroom. On the second floor is going to be a theatre room, pool table and full wet bar.

The biggest issue I am having right now is the height needed for the lift I will be placing in the bay on the left, picture below. Floor to ceiling will be roughly (at this point in my plan) 151" to clear the necessary space for the lift.

The picture below with labels A and B are showing the sides of the floor joists that are stumping me. I can not get them shorter than 18 feet with this current setup and that is going to be with 2 I beams running from front to back to support one end of those joists. I have read that a 2x12 can support that span with no problem but I am just having trouble believing that.

So, looking for some ideas/recommendations on what to do in the situation. The pool table is planning on being on the middle portion of the upstairs, so I am not concerned with the weight there. On side A will be the theatre room and side B will be the full wet bar. I am looking for no movement when walking through the upstairs.

Thanks everyone ahead of time!!

 

[firebirdparts]

Doesn't sound too bad to me already. Is this a two story building or a one-and-a-half story? If that's an upper half story, I would be already thinking about how the roof ties into that floor.

Floor trusses would be the next step up above a 2 by 12 for me. Some people use I-joists to go longer,. I don't like them. They're fragile and you can't run anything through them, where floor trusses are a joy to work "in". You be the judge.

 

[groberts4444]

Doesn't sound too bad to me already. Is this a two story building or a one-and-a-half story? If that's an upper half story, I would be already thinking about how the roof ties into that floor.

Floor trusses would be the next step up above a 2 by 12 for me. Some people use I-joists to go longer,. I don't like them. They're fragile and you can't run anything through them, where floor trusses are a joy to work "in". You be the judge.

It's a whole second story, that would be a pretty goofy roof if not! ha

Thanks for the reply. Understanding that floor trusses would be a superior option, would 2x12's not work in your opinion? Should I go down that road, should I consider 12OC instead of 16?

 

[Bigblockyeti]

The considerations are live load, dead load and acceptable beam deflection. Without running the math, guesstimating only I would call 2x12 @ 18' span acceptable but I would place them 12" O.C., even at that it could feel a bit bouncy in the middle.

 

[Jlbc212]

Boise Cascade has an on-line beam calculator that is easy to use if you understand building construction - live loads, dead loads, concentrated loads, deflection, bearing, etc.

 

[firebirdparts]

2 by 12's at 18 foot will work. The exact rating at 12 or 16 centers is going to depend on the wood, and you'll never load that floor to the exact design rating. There are many grades. Design work is very exact and of course your life in that building is not exact at all.

In fact, you can do that with 2 x 10's on 12 inch centers in the very best grade of SYP. FWIW.

 

[socoj2]

https://www.socomp.com/wp-content/uploads/2014/02/FloorSpan.pdf

Floor Trusses man with the cost of 2x12s. when i went to scissor trusses it saved me money over 2x8s and a Ridge beam.

you can run 2x12s up to 18' - 5" for a 60 psi live load 16" oc

https://www.engineeringtoolbox.com/floor-joists-span-d_1479.html

 

[wssix99]

Floor to ceiling will be roughly (at this point in my plan) 151" to clear the necessary space for the lift.

You need to go higher. If you build to 151", you'll get that measurement at your door. Your garage floor will have a slope to it, which will shorten the floor-to-ceiling height in the middle of the bay. (Right where you want to put the lift.)

So, you'll want to have a concrete discussion now, figure out your slab slope, and then add a few inches to that. You will need space for flooring variations and also a little extra space to allow you to stand the posts from horizontal to vertical.

I think I only have 2 inches between my posts and ceiling and it wasn't enough to stand the lift up in place. I had to stand them up at the door (where my floor-to-ceiling is larger due to the slope) and then slide/walk them into place standing up.


+1 on Floor trusses. The company will calculate them for you, you can build in utility chases and also choose your deflection and other characteristics.

 

[ddawg16]

Have you considered engineered I-Joists?

A bit more expensive, but I believe their stiffness will be better than sawn lumber.

 

[ksgar]

Our detached garage is a 2 story 44 x 44. We used engineered I joists as pictured by the previous reply. They rest upon a steel i beam that spans 2/3 of the width of the garage. There is an RV bay that accounts for the other 1/3 of the width of the garage. Our joists run from the garage doors on the front of the garage to the back of the garage, which is the opposite of what you plan to do. Our walls in the non-rv bay are 12 feet high, with concrete foundation walls 3' above the floor...so the studs are 9' on top of the foundation. We also plan to build a wet bar with a pool table and shuffleboard on the second floor, and at this point in time the second floor is insulated but not sheet rocked. We have a small bathroom on the first floor, and we have a second bathroom on the second floor. There is an unfinished attic storage area over the RV bay. Oh, our first floor joist span in the non-rv bay area is 22 feet. Our detailed framing plans were developed by our lumber supplier and double checked by their in-house engineer.

Good luck on your project!

 

[groberts4444]

The considerations are live load, dead load and acceptable beam deflection. Without running the math, guesstimating only I would call 2x12 @ 18' span acceptable but I would place them 12" O.C., even at that it could feel a bit bouncy in the middle.

Acceptable beam deflection for me is pretty minimal (my OCD does not adhere to real life circumstances most often). The live load on the "theatre" side of the 2nd story is going to be minimal. Couches, recliners.... that's really it.

2 by 12's at 18 foot will work. The exact rating at 12 or 16 centers is going to depend on the wood, and you'll never load that floor to the exact design rating. There are many grades. Design work is very exact and of course your life in that building is not exact at all.

In fact, you can do that with 2 x 10's on 12 inch centers in the very best grade of SYP. FWIW.

100% agree.

Floor Trusses man with the cost of 2x12s. when i went to scissor trusses it saved me money over 2x8s and a Ridge beam.

you can run 2x12s up to 18' - 5" for a 60 psi live load 16" oc

This is great input, thank you!

You need to go higher. If you build to 151", you'll get that measurement at your door. Your garage floor will have a slope to it, which will shorten the floor-to-ceiling height in the middle of the bay. (Right where you want to put the lift.)

So, you'll want to have a concrete discussion now, figure out your slab slope, and then add a few inches to that. You will need space for flooring variations and also a little extra space to allow you to stand the posts from horizontal to vertical.

I think I only have 2 inches between my posts and ceiling and it wasn't enough to stand the lift up in place. I had to stand them up at the door (where my floor-to-ceiling is larger due to the slope) and then slide/walk them into place standing up.


+1 on Floor trusses. The company will calculate them for you, you can build in utility chases and also choose your deflection and other characteristics.

I only need (according to the lift manufacturer) 144 1/2 inches from floor to ceiling. The concrete work is already factored into my heights shown in the drawing, as all of the concrete work is not shown, but is under the top of the slab that is shown in the drawing

Have you considered engineered I-Joists?

A bit more expensive, but I believe their stiffness will be better than sawn lumber.

I have considered them, but have never used them. Not to say that I wont go with them, just looking to learn more about them

Our detached garage is a 2 story 44 x 44. We used engineered I joists as pictured by the previous reply. They rest upon a steel i beam that spans 2/3 of the width of the garage. There is an RV bay that accounts for the other 1/3 of the width of the garage. Our joists run from the garage doors on the front of the garage to the back of the garage, which is the opposite of what you plan to do. Our walls in the non-rv bay are 12 feet high, with concrete foundation walls 3' above the floor...so the studs are 9' on top of the foundation. We also plan to build a wet bar with a pool table and shuffleboard on the second floor, and at this point in time the second floor is insulated but not sheet rocked. We have a small bathroom on the first floor, and we have a second bathroom on the second floor. There is an unfinished attic storage area over the RV bay. Oh, our first floor joist span in the non-rv bay area is 22 feet. Our detailed framing plans were developed by our lumber supplier and double checked by their in-house engineer.

Good luck on your project!

So I will be looking to do something similar to this. The floor trusses, joists, Ibeams...or whatever I land on, from the left to the right side of the first garage bay will sit on a steel beam running from front to back.... same with the right side of the building and the left most side of the right garage bay (hopefully that was not too confusing).

 

[groberts4444]

I should probably also add in that there will be foundation block coming up from footers and concrete. It is not illustrated in the drawing attached....

 

[Toolfool]

I don't think I have built a floor system with sawn lumber in over 10 years. As lumber quality continues to drop, engineered lumber products have become more accepted. I-joists are FLAT , can span greater lengths, and allow for more electrical and plumbing penetrations. A no-brainer.

 

[dcg9381]

Having done a house with traditional table spans and 2x12, I wouldn't do it again. Floor loading is correct, but add a toddler or a large dog and it's pretty bouncy.
Trusses are the way to go.

 

[theoldwizard1]

2x12 would probably be my last choice !

Floor truss - lightweight and incredibly strong

Wooden I-joist (like ddwag16 said).