Supporting Roof Without a Center Post?

[sr77]

Hello, I have a 23x22 foot garage that I have a work area while also parking 2 cars in it, one being a classic car so i am trying to make sure the garage is safe. It is 22 ' wide and has 2 2x12(or 10 I'll have to check) beams running the width of the garage. I had a neighbor over the other day who is a contractor questioning why I don't have a center post in the middle of the garage under the beams. My questions for you guys are:

1) for my 22' wide garage should I have a center post support under the 2 beams or do you think I am ok with the setup I have? I really, really like the openness of the garage without a center post especially with 2 cars in there and being able to have plenty of space to get around while I am working on them.

2) If you think that my roof is not supported enough without a center post, is there another alternative to supporting the upper section without using a center post so i can leave my garage open? There is nothing above the garage other then the roof, I put a few sheets of wood on one side for a little extra storage but that it.

thanks for the help! I am not in the business so you might have to explain things in laymens terms.

 

[nadogail]

Trusses? Lots of wide open spaces are spanned with trusses without centerposts. They seem to hold up well, the Pedro Domeq bodega in Jerez de la Frontera, Cadiz Province, Spain has trusses designed by Henri Eiffel (he did the tower in Paris)

 

[Torque1st]

If you are worried have a structural engineer come in and take a look.

 

[kwb]

Not enough information for anyone to make an informed response.

If they are trusses- then you shouldn't need a post.

Other framing (which is my guess given mention of 2x10 or 2x12) then pictures are needed.

 

[rsanter]

if the center of the garage need support then you either need a post or you can install a beam to carry the load and the beam will be supported at each end with a post

bob

 

[GN4WHLN]

+1 on the trusses. That and load bearing walls or posts. In my own garage I doubled up the 2X10's on the lower chords and ran bolts through everything. I am in the process of building some additional braces from steel rod. For the most part, my concern was that an earthquake with a good sideways thrust would shift the roof off the wall enough for it to fail.

 

[KCarGuy]

My Garage is 30 feet wide and the Joists run from Left to right. We put a Steel I-beam that runs front to back (closer to the 2 car door) and overlapped the 2X10 Joists by 3 feet.
I did not want a center post (for extra room also) and I did not want Trusses (because my second floor is for storage and an extra "Play Room", so I wanted it Wide open)
It worked out great and the I-Beam was not that expensive.
The Second floor will hold a Machine Shop if I wanted to...

 

[krooser]

two 2X12's should be able to handle the loads quite well... but I'm not an engineer.

Mu old 20X20 lasted over 50 years with 2X6 joists connecting the walls on 32' centers... it was stick built without trusses. Does your garage have a "hip roof" or "gable roof" design? Not sure if THAT would make a difference.

 

[buening]

Definitely need more info on what is above. Are the two 2x12's sandwiched together, equally spaced (at 1/3 points of the joist span), or?

If you look down the bottom of the beam, can you visually see it deflecting?

 

[KCarGuy]

One of the things that helps when Sandwiching a couple of 2x's together is using a 3/4" piece of plywood in between the 2x's and installing the 2x's "Crown Up" this will help from long term Sagging.
A good friend is a Home Builder for the last 30 years and when we built my Garage, he made sure that everything was installed "Crown up" by checking the grain and doing a "line of sight" check, but looking straight down the board and checking for a Crown.
He then marked everything with an arrow, so it all went in correctly.
If you do choose to use 2x10 or 2x12's, glue and nail them together with 3/4" plywood between them, this helps even more with strength.
You would be surprised on the weight that will carry.
We also layed a 2x4 atop of the beam (for nailing into). You would not need to do that.

 

[sr77]

thanks for all the replies

My camara is broke so if I can get access to another one I will post up some pics. Its basically a stick built garage with 2 2x10s running the width of the garage. The joists are definitely not to code as they are randomly spaced out, some 2-3 feet! And between the beam and the top of the roof are a few 2x4s holding it up. It was built about 30 years ago and definitely wouldn't past code today. While the trusses would be a great way to go, I don't have the budget to redo the whole upper half with new trusses, etc. thanks again

 

[tcianci]

Please, explain more...Are the things you are calling beams really just acting as collar ties? Are they tying the 2 walls together? Is it a gable roof garage annd is the ridge running 90 degrees to these "beams". From your breif description I envision a typical frame building, with the 2x's running at 90 to the ridge. In this case, notice that the weight of the roof is bearing on the outside walls and the 2x'x are keeping the walls from spreading. The ties are then in tension and the only reason for them bneing beefy is to keep them from sagging of their own weight. That may be the reason for your 2x4's they are actually hanging your ties to keep them from sagging. If the building is 30 years old and the ridge isn't sagging, just leave everything alone. When you say the joists are randomly spaced out, which joists are you refering to? The 2x10's or12's or are the rafters spaced out? Pictures would be great. I am a licensed construction supervisor and residential contractor, from the information you have provided, your building is probably fine since your building has no ceiling.Lots of folks and possibly your contractor friend too cant seem to comprehend that the weight of the roof rests on the outside walls and the ridge is supported by the opossing forces of the rafters against each other. In the case of a completely open span, with no framing tying the walls to each other across the building, you would need what is refered to as a "structural" ridge where the ridge is supported by supports under it at each end of the building. The fact that the ridge is then able to have a load path to the foundation of the building allows it to actually let the rafters "hang" from it. This cancells the spreading force that the rafters usually apply to the outside walls

 

[Torque1st]

Please... We can play around with pictures and posts here but it will not mean anything until he has a licensed professional engineer or architect inspect the structure personally.