Ceiling Joist Calculation

[jasonz]

This is related to my shop that I'm building http://www.garagejournal.com/forum/showthread.php?t=305729

In the wood shop, it's basically a 24 x 25 room with 10' walls. I do plan on using the area above for storage. Nothing too heavy but I will be walking around up there.

I'm using my current garage as a template but I want to make sure I'm not building something that is unsafe. So, if anyone has a good resources for figuring out max lengths and when to use a support beam and recommendations on wood species.


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[jack stand]

I'm guessing that this will be attached to your new shop? Looks nice by the way & congrats! I'm also asuming that you're wood framing it, so if time is an issue (like your wife said about your big shop) I'd just order trusses from who ever you might deal with, that is there are some truss co's that will deal directly with you and others that will work through a lumber supplier. Tell them your "wants" and they will have several options that will depend on your desired roof height (pitch).

 

[xyster101]

Are you going to have was above also our just a roof?
I did rafters because I wanted a wide open attic space but trusses are faster and easier. You can get attic trusses.
That said I used 14" tall engineered joists that were 24' long for an open span below. I can park my atv and my 60" Ferris mower that is 9 feet long in the attic with no fleecing. The joists were expensive.

Posted by my Galaxy S3. Sorry for typos

 

[schor]

Contact and engineered joist/truss company and ask them what you need.

For that span your probably looking at something in the 14-15" range and usually you require a flooring glued and screwed to make it all work.

Can you put a beam down the middle and 1 post, then you can probably get by with 2x8's.

 

[matt_i]

I would talk to your local lumberyard. My guess is they have a calculator for such. It looks like it might work out better to use I-joists than solid timber, for this particular length. A clear span is always nice. But, as stated, bracing is key so pay attention to how the manufacturer recommends or requires it to be braced.

 

[Justanoldguy]

Are you going to have was above also our just a roof?

You lost me.

 

[jasonz]

So I'm building a room inside the building. The idea is to isolate the woodshop so that I don't get saw dust all over everything else and I can double insulate it so I can work year round in the woodshop.

Thanks for the suggestions, oddly enough, I never thought about calling up a lumber yard.

 

[My Old Tools]

http://parkeronline.org/DocumentCenter/Home/View/732

 

[lawsco01]

Hi Jasonz,

I am looking to do some work to the ceiling in my garage also. My advice is to contact an engineer. A couple hundred dollars is worth the peace of mind. This is what I will be doing.

 

[Falcon67]

Span Tables is what you want.

http://www.awc.org/codes-standards/publications

For my shop, I believe it was Douglas Fir 2x10 that would span my 24' with no snow load. Nobody stocked 2x10 here, so I used 2x12x24 Doug Fur. I have some OSB decking in the attic and can pretty much throw anything up there that will fit in the 2'x4' hole.

 

[jasonz]

http://parkeronline.org/DocumentCenter/Home/View/732

This is good... but it only lists Douglas, Him and Southern Pine... #2 at that as well... this is good info but I think there are better species out there that can get you longer spans.

 

[jasonz]

Span Tables is what you want.

http://www.awc.org/codes-standards/publications

For my shop, I believe it was Douglas Fir 2x10 that would span my 24' with no snow load. Nobody stocked 2x10 here, so I used 2x12x24 Doug Fur. I have some OSB decking in the attic and can pretty much throw anything up there that will fit in the 2'x4' hole.

Perfect, this is exactly what I needed! Thank you! Just have to make sure that the material that available matches the load numbers.

 

[matt_i]

This is good but "no snow load" basically means "no additional load" other than the timber structure and sheathing itself...

 

[jasonz]

Good thing the frame is inside the building and not part of the overall structure. So I don't have to worry about snow load or sheering.


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[matt_i]

I was referencing this

I have some OSB decking in the attic and can pretty much throw anything up there that will fit in the 2'x4' hole.

 

[Falcon67]

This is good but "no snow load" basically means "no additional load" other than the timber structure and sheathing itself...

We don't do snow here. 2" is about 10 lbs sq/ft. If we do get it, it lasts maybe a day or so. Table C1 - depending on the modulus - shows a easy 2x10 span of 24' @ 24" OC with a 10 lb live load and 5 lb dead load. My OSB ceiling is 1.72 lbs sq/ft dead load. Spreading normal storage out with OSB sheets should be easy to keep under 10 lbs live load unless it's maybe pallets of engine blocks. There's no give on those 2x12s when my 200+ lbs is crawling around up there.

 

[jack stand]

So I'm building a room inside the building. The idea is to isolate the woodshop so that I don't get saw dust all over everything else and I can double insulate it so I can work year round in the woodshop.

Thanks for the suggestions, oddly enough, I never thought about calling up a lumber yard.

OK not an addition to your shop. We just used and "engineered" floor joist on a 24X24 garage with a full span and normal living space (load) above it. They were 12" depth and 12" oc. There is some noticeable deflection or bounce but not bad. This is on a $2 million+, 7049sf (finished space) house that has an engineers stamp on it. The floor system uses both the "TJI's" or Truss joist and the open web type.

 

[schor]

So I'm building a room inside the building. The idea is to isolate the woodshop so that I don't get saw dust all over everything else and I can double insulate it so I can work year round in the woodshop.

Thanks for the suggestions, oddly enough, I never thought about calling up a lumber yard.

Once I read your build thread I knew what you were doing. I'd find out what can span the 24' for a floor joist. Then you can put pretty much anything you want up there.

 

[jasonz]

OK not an addition to your shop. We just used and "engineered" floor joist on a 24X24 garage with a full span and normal living space (load) above it. They were 12" depth and 12" oc. There is some noticeable deflection or bounce but not bad. This is on a $2 million+, 7049sf (finished space) house that has an engineers stamp on it. The floor system uses both the "TJI's" or Truss joist and the open web type.

Once I read your build thread I knew what you were doing. I'd find out what can span the 24' for a floor joist. Then you can put pretty much anything you want up there.

Roger, Roger...


Dr, dr...