Expert: Dan Griffin - 9/29/2010

Question
i had a contractor do a porch and roof just a few months ago . the building inspector approved the plans . after the job was complete the inspector came back for the final inspection . the contractor used doubled syp no1 2x12 glued and nailed sitting back in the house and 3inches on a notched out 6x6 pt and carriage bolted too. after the inspector signed the final inspection it passed . 2 weeks later i recieved a phone call that the project was no good he said it had to be a doubled LVL 11 and a quarter microlam said the span was to long the span is 11ft 7inches he said you are only allowed 9ft 9 and a half is this right ? its kind of funny i have been in the building feild for 27 yrs but had to quit for health reasons . and everytime this inspector needed to know anything he had to refer back to his BOCA book now the job is complete but we are not allowed to use it unless we put 2 more 6x6 post in the center of the 11ft 7 span going out from the house .

Answer
Dave, now is time for all the standard disclaimers about consulting and working with a structural engineer in all such matters.

I'm not real sure I know what the problem is.  I'm guessing you have built a porch roof.  The rafters rest on the house at one end and extend over or to a new outside beam that is resting on notched 6x6 columns.  The columns are 11'-7" apart.  I don't know how long the rafters are to help determine the load on the beam.

I'm not sure if you are dealing with a beam/girder or with a header.  Girders are used to carry heavier loads like the center beam in a house and usually 3 or more layers of dimension lumber
An old "seat of the pants" method of working out header sizes using dimension lumber to carry building loads in an outside wall was to use an inch of header for each foot of span.  A doubled 2x6 could span a 6 foot opening, doubled 2x12 could span a 12 foot opening.  This would typically carry the roof load, in fact it would normally carry a second floor and roof load.  I am guessing that is how your contractor arrived at his use.  I'm still not sure what loads you are carrying.  

Arguing with inspectors is a bit like wrestling in the mud with pigs, sooner or later you realize they kinda like it.  Ask him for a clarification on his calculations and a cite from the current code section.  You might ask him what load per foot he is using.  Consult with your contractor on his figures.  A good builder's lumber yard should be able to give you the load bearing capacity of the microlams he is asking for and the capacity of a doubled SYP beam.  I would expect the deflection requirement would be L/360, though L/240 is often used for ridge beams.  Here is a short course in loads and make sure to note the table available at the bottom of the page:
http://bct.eco.umass.edu/publications/by-title/sizing-engineered-beams-and-heade...

I wish I understood better how this beam is functioning.  I don't know how to address the issue of being finaled and an after-the-fact rejection.  It would seem to be a thin ice issue for the inspector.  If you have a certificate of occupancy, I'm not sure that he has a solid leg to stand on.  There should be some middle ground to work out with the inspector.  You might ask him about a flitch plate installed on the existing  beam, adding a third 2x12 to the beam, adding knee bracing from the columns to the beam.  Your contractor may have some other ideas.

I wish I had an instant reference to help you.  If I understood what this beam was doing, I might be able to help more.  Remember these words when dealing with an inspector:  yes sir, no sir, I'm sorry I don't understand sir, can you show me in the code book where this is addressed sir, etc.