Re: 16' Garage Door Headers
incognito said:
Well it sure is re-assuring to see that todays building officials are no longer capable of determing if a 16' garage door header will provide adequate support. We have passed enough code requirements to regulate ourselves right out of a job.
Just about anything can span 16-ft. The biggest thing is determining the size of beam to make sure it doesn't deflect too much. Deflection can be critical so that the header beam does NOT jam up the door.
The point is, who is a person that is NOT licensed or qualified to prepare the calcs in the first place qualified to question the decision of a registered design professional and say it is wrong. Do you even know how to even perform the math?
The work around to that is have the calcs checked over by someone who would be equally qualified as the RDP to check the calcs if there is a question. If I was a B.O., I could not lawfully question the calcs of an RDP regarding work on a non-exempt building without literally engaging in the activity and risk of claiming oneself to be duly licensed and registered. In other words, to claim that you know better then a licensed architect or engineer (regarding anything that is not part of the prescriptive path of the codes) is to claim yourself to be duly qualified and therefore licensed and registered. Since you don't want to do that, you can hire/contract or use in-house Engineers (the Engineering Department) to evaluate the calcs and give a professional report of findings and from that findings can make a decision.
You are not out of the job, you just have the calcs that you are not qualified to be able to competently perform because you are not qualified to prepare the plans in the first place - to be evaluated by a qualified professional (expert witness) and give a report. After findings are made, then you can make a decision. This is what a prudent B.O. or Plan Reviewer should do.
Of course, some are duly qualified because of being licensed. If it were me, I would take the due diligence.
Because the OP's original post pertains to a structure that would be exempt in Oregon - I would give a simple suggestion on beam sizing.
I would suggest that the beam size would be a solid timber beam of 12" x 14" (or equivalent Built-Up Beam or Glu-Lam or similarly dimensioned steel beam). I would size the front wall studs to be 2x8 (instead of conventional 2x4 or 2x6. The corners would be a 12x12 built-up is equal size solid timber, laminated column, steel column I-Beam (W12), Steel Tube column (12 x 12 square) with conc./grout fill with reinforcement bars, or reinforced concrete columns.
Connection details, connection systems, anchorage systems and shear wall paneling would have to be spec'd by you to your local codes and load systems. I can not spec any more without detail knowledge. Also, reducing the size any further would need more info. With as little information as it stands, I'm specing a little on the over-built side.
However, a hefty 12x14 beam would be pretty good even on simple beam calculators. It would of course be Douglas Fir - Select Structural grade. If conditions are unusually extreme, I would be going to about 12x18 (built-up made of 2x12s in stack style similar to glu-lam). This would be a reasonably stout header. However, there are a number of detail nuances that exceeds the scope of the general suggestion of sizing but you as the designer will have to decide what is needed and weigh it with the economics and other factors. These specs, I am pushing 900 to 1000 lbs. / ft. of unsupported beam span.
That would be quite a bit on the extreme side.