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I’m a pharmacist who’s trying to create more space in my stock room. I want to build an additional level about 8 feet above the existing concrete floor (I’ve got a pretty high ceiling). I can fasten one end of the joists to a block wall, but the other will need to be supported by a beam perpendicular to the joists. (Please pardon my terminology–there’s probably a name for such a beam.)
I’ve been able to find a reference that says I can use 2×8’s for the 10 foot joist span, but I can’t find anything that tells me how big the cross beam has to be. It will be spanning 10 feet 5 inches and will be resting on 4×4 or 4×6 posts. Will doubled 2×10’s work or should I go to doubled 2×14’s? Flooring will be 3/4 inch plywood and the joists will be 16 inches apart.
I’d really rather not have the whole contraption fall on me some day, so I don’t mind if it’s overengineered. I just can’t seem to find out how heavy the cross beam needs to be. Any thoughts from the pros?
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Dear Tom,
Pros call their engineers. We would discuss the expected worst case loading first then we would decide on beam requirements/as per code.
Don't use free advice from people you don't know if you don't want to test your liability insurance.
*I have to agree with Gabe on this one.It is very difficult to give an accurate answer to your question as there are many more variables than you have probably thought of such as how much does the stuff you are going to put up there weigh, how thick is the concrete floor and what's under it, is it capable of carrying the concentrated loads created by the posts, how were you planning to attach the joists to the block wall?The project doesn't sound to difficult, it's just hard say without actually seeing the site.
*"Rules of thumb" can be very imprecise, and there are a lot of variables that should be looked at, especially if you are going to use the room for commercial storage, which is the case here.A couple rules of old rules of thumb I've heard are:1. Floor joists at 16" on center. The depth in inches is equal to the span in feet, divided by two, plus two. 10 foot span divided by two = 5, plus two =7, therefore use 2x8's 16" on center.2. Locally, for residential bearing wall headers (no snow), the rule of thumb is the 4x's for single story or top story, 6x's or equivilent for ground floor of two story houses. The depth in inches is equal to the span in feet. Here, that rule of thumb would imply a 6x12 or better.There are 3 equations that are required to be looked at for beam design. Equations for deflection, bending, and horizontal shear, at least in the UBC. Each beam is an individual, especially in commercial applications. Residential live loads (not including structure) are usually 40 PSF, while commercial storage loads can be 100 PSF of higher. Someone needs to calculate the tributary load on that beam and do the calculations. It shouldn't be difficult. The charts for Truss Joist MacMillan minilams could be used. I have a program I wrote years ago that will do just that, but I'm licensed as an architect & G.C. only in California. Home page http://home.att.net/~g.wheelerI had a client who recommended I consider being a pharmacist like his kids. The hours and pay and education required are better than this field.
*The above (3.) assumes a good grade of douglas fir, say #1 or #2. Grade and species has a big effect on strength and deflection.A non-engineer or non-architect can do the calculations, but not absolutely safely. That's why rules of thumb, experience and intuition are important, they help us check the answers for reasonableness.
*If they know how, a non-engineer or non-architect can do calculations as safely as anyone. They just can't take any responsibility for them or the consequences of them. Nor can they ask any building official to accept them.The question only addresses gravity loads, but lateral loads are just as important if not more so. Rule of thumb: anyone who does not know enough to ask about lateral loads cannot calculate them safely.
*It depends on the State or locality. In America, a person can be held liable for just about anything, regardless if they are licensed, unlicensed, an owner or lay person.
*Storage floor loads can be as great as 200 psf. 10' x 10.5' = 105 sq.ft. x 200 = 21,000 pounds (assuming that this structure will not have to carry any addtional loads) the new beam will have to support 10,500 pounds (1000 plf (pounds per linear foot))and the columns at each end will have to support 5250 pounds. The columns will need footings and the whole structure will need to be braced to prevent racking (lateral load). The ledger at the CMU wall will need to support the same amount of weigh as the beam and typically the CMU will need to be grouted solid at the bolt locations. The CMU wall footing should also be looked at in order to insure that it can support the addtional weight.Hire an engineer
*To Rd - Actually, the center support would have more than half the load on it. A beam with center bearing will have roughly 5/8 of the total load in the center, and 3/16 of the load at each end. I was a truss designer for many years. It always aggravated me that even though I knew what I was doing, I had no degree, so what I said meant nothing. I had years of experience in designing trusses and beams, but no peice of paper to back it up with. My suggestion to Tom Connelly would be to have the beam specified by whomever you buy it from. That way, they're liable for it, and they know it. There's no way a legitimate business is going to specify something inadequate.
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Ron:
I doubt that Tom Connelly can buy a beam from someone who will be "liable" for its actual use.
As an engineer, I reiterate comments made by the other respondents, hire an engineer or a competent designer to size the member. Rd's mention of storage loads is correct, and in some cases not conservative enough. What are you storing?, how high?, what seismic zone do you reside in? what about railings (codes are very specific as to height and lateral loading on these elements)? what about connections?
Its not rocket science, but does require a specific design. I would not rely on any "rules of thumb", nor would I use (or provide myself) any beam sizes/grades offered in this forum.
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I agree with the above, from an abundance of caution.
How much would y'all expect him to pay the engineer? Do you feel he can assemble the structure himself, once it is specified?
*Fred - Glad to have a real engineer around. I used to tell people I was a P.E. - a "Pretend Engineer". (-:Maybe I didn't say what I meant well enough about buying/designing the beam. I never sold a beam unless I knew where it was going and where it was going. For instance - I got a call from a local homeowner last year. He wanted to remove a load bearing wall in his house, and wanted a beam for it. He told me the 2nd floor joist ran parallel to it, and there was no roof load on the wall. I wouldn't sell him the beam until I actually visited the house, and found out for myself. Turns out he was wrong on both counts. I measured the tie-in spans for myself, and sold the guy a beam. My point was that this gentlman should do something similar - buy the beam from whomever specifies it. Only a fool would design and sell the beam without knowing for sure how it would be used.
*Maybe we shouldn't get too distracted by size of the beam. If we back up and look at this, is this something that's going to be built without a permit or inspections? I assume this is a new storage mezzanine in an existing building, perhaps leased or rented. And a real need to cut costs. Is there going to be a proper stairway with legal slope, handrails, landings, guardrails, lighting? Will the foundation be done properly or will it cause the floor to crack. Will the whole thing be properly cross-braced? Will it be insulated, wired, and air conditioned properly? Will this interefere with exits, fire sprinklers, fire walls, fire rated ceiling, or handicapped access? Could this open an ADA suit because a worker can't get up and down the stairs because of a bum leg? Will the next tenent be storing heavier materials up there, like car parts or bulk paper? Will the added square footage affect something as remote as restroom quantity, exits, fire resistance, taxes or parking requirements?We could be opening a can of worms trying to encourage him by answering a seemingly simple question. Oops.
*Gary, you ought to be a lawyer. Excellent.
*How about just building shelving to the ceiling and get a rolling ladder a la the "big boxes".Rich Beckman
*... and I bet you could just buy commercial heavy-duty steel shelving "off the shelf."
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I don't get on the internet too often so just checked back for responses. Info is great for background, but y'all have convinced me to check with an engineer.
(Please keep this exchange in mind the next time you stop by a pharmacy to pick up that cold remedy your brother-in-law, the non-pharmacist, recommended.)
I've checked into commercial shelving like in the warehouse stores--almost got some from a bankrupt Best, but was beaten by a guy with a faster truck--but it would be cheaper to build a whole new structure.
And the liability issue is huge. My pharmacy is currently involved in a slip-and-fall suit where our only connection is that we're the property NEXT to the property where the "victim" fell. I think anyone who's been on the receiving end of this kind of suit is real reluctant to go after someone else unless the negligence is particularly obvious.
Thanks again for setting me straight.
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Speaking of handrail codes...Went into the downtown engineers building, not easy to find but right on the main drag and sidewalk...So I find the door and enter, all looks so nice in this renovated city building with the new wide steel staircase and all..Then I grab onto the oversize oak board handrail to zip up the low rise, larger tread comercial code stairs and wait a minute...
b Oversize beautiful oak railings aren't code~!@@!!
So what do codes do and what do their enforcers do except live with the comfort that they get paid vacations now, have less stress and yes that big one, a retirement fund!
Near the stream building the way I want to(O)!
J
*They also may have a job for life if they don't do anything too stupid. It used to be that Public Employees got paid less, but they had more security. With the legalization of unions in pulic service jobs, they now have good pay, good benefits, security, and an attitude.The bizarre modern looking projects published in the slick architectural magazines often have illegal or dangerous handrails or guardrails. The problem is not just with the traditional looking handrails.
*Don't those "slick" architect's palaces ever get inspected? That is, by an inspector who actually has read the Code? :)
*I wonder if those "Alternative Building Codes" they now have in some states (at least CA) apply to safety features like that? - wasn't that FHB that I read about them awhile back? - yb
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I'm a pharmacist who's trying to create more space in my stock room. I want to build an additional level about 8 feet above the existing concrete floor (I've got a pretty high ceiling). I can fasten one end of the joists to a block wall, but the other will need to be supported by a beam perpendicular to the joists. (Please pardon my terminology--there's probably a name for such a beam.)
I've been able to find a reference that says I can use 2x8's for the 10 foot joist span, but I can't find anything that tells me how big the cross beam has to be. It will be spanning 10 feet 5 inches and will be resting on 4x4 or 4x6 posts. Will doubled 2x10's work or should I go to doubled 2x14's? Flooring will be 3/4 inch plywood and the joists will be 16 inches apart.
I'd really rather not have the whole contraption fall on me some day, so I don't mind if it's overengineered. I just can't seem to find out how heavy the cross beam needs to be. Any thoughts from the pros?