[JYL]

I have a "Old Barn" looking Bean 12 x 11 1/2. Not sure of the exact species but it look like a Douglas Fir. The Beam is already installed and is 38 feet long. Beside the end columns, their is (1) additional columns at about 14 feet of one of the end. So, likely a clear span of 13 Feet and 24 feet respectively. (all the columns are also 12x11 1/2)

At this time, it support the front of a mezzanine. The mezzanine itself is 12 feet deep. The floor is not really bouncy -- but their is almost no weight beside the floor structure.

Now, I want to convert the mezzanine to a full second floor. Therefore, the beam will become a mid-point for a 12 Foot wide floor (one side) and a 16 foot wide floor on the others side. Total 28'.

I am planning to demolish the existing mezzanine and use 28 feet I-Joist (suitable for a 16' span). But still using the 12x12 beam as a load bearing for the floor. (it is a very nice looking beam -- nice patina and all).
Design Criteria: I use Live load 40 death load 10. (This is a pole building 38x28... so, the beam does not support anything beside the second level floor)


I am trying to estimate the maximum potential "Clear Span" of this somewhat unknown beam (Said, maybe Douglas Fir). In fact, this is to make a budget because I am convince I will have to replace the concrete floor by a suitable Footing. $$$ Furthermore, if I need to move the existing mid-span column, this will be complicated and expensive.

I did not find on Internet how to calculate for such a large beam.:crying:

 

[Nealtw]

will it be finished space below? How thick is the floor? any chance of a partial wall?

 

[JYL]

Bellow: This is a woodworking shop. I think the wall will be finish with some plywood. I am not sure if the ceiling will be finish. If it is, this will be 5/8 X-rated Drywall. I will not go with anything else since the "stair case" is pretty far away from any doors. (Well, I am insisting to move the stair closer to an exist door... or install a door closer to the stair)

At the same time, one of the objective of this project is to reduce the "Dust" on the second floor. So, it is likely the drywall will be installed (maybe with some plastic sheeting).

Load Bearing Wall idea: This will be evaluated as an options. But, she handle a lot of 4x8 sheet of plywood. Without some clear span, this might be slightly more difficult. For example, she might have to change the orientation of the "table saw". You can see on the picture that she sometime hit the beam when she feed the saw.

Regarding the concrete: I was trying to reach the company that build the Pole Building. But, they are out of business. The only information I have is that this is a standard pole building, 12 feet between the post. Clearly, a "Plan" have been followed and the craftsmanship of the main structure seem PRO level.

Regarding the concrete floor, this building initial goal was parking a large RV (The garage door -- that will be removed -- is 14 feet high). Therefore, for the moment I am assuming the slab is likely 6" thick with #4 rebar every 16". But, this will have to be verified.


Looking at the picture, I realize that the beam is not 38'. This is likely one of the reason they installed the column. So, the largest beam is likely 24 or 25 feet long. (The beam is strait and does not bow at all)