determining beam size

[John]

Hey everyone,

I'm pushing my carpentry skills a little by building a small porch onto a corner of my house.

I'm in the planning stage right now, and I'm trying to determine beam size. My porch will be 8 feet deep, but 16 feet wide. I was hoping to get a beam for the front 16 foot wide end of the roof that can be held up by just 2 posts, one in each corner. I've got a few tables from a deck building book that does not have anything to span 16 feet.

I've talked to a couple of builders, and they tell me they just ask the folks at the lumber yard. I'm looking to find a chart that will help me determine for myself.

any suggestions?

-Thanks,

jeff

[Colbyt]

My book did not have that table. You are wise to see it in writing before proceeding.

You do need to consider the load on the beam including snow load in the winter. I have a similar sized porch on a house that I own. Based on the finished size of the beam, it can't be more than 2 2x12's spiked together (more likely 2x10's) and covered with 1x stock. I have owned the house for

25 years and I would guess the porch has been there for 60 years. I replaced the posts 10 years ago with 6x6 PT lumber.

A porch on another house 6x12 supports the roof load with a single 2x8. That one I consider a little underbuilt but it has been there 20 years that I know of.

Here is a Google search that may lead you to something in writing:

Colbyt

[Doug Miller]

Visit your local library and look for texts on mechanical engineering. "Simplified Design of Structural Wood" and "Simplified Mechanics and Strength of Materials," both by Harry Parker, are particularly comprehensive _and_ comprehensible.