Messages and Online Forum Q&A

Re: Beam Spans

From: info@builderswebsource.com
Category: Structural
Remote Name: 63.198.181.43
Date: 14 Jun 2001
Time: 09:41 PM

Comments

To determine the maximum spacing between supports, we use the following design parameters you provided in your messages:

Total Car Port Width = 28 feet

Overhang = 2 feet each side

Snow Load (Anchorage Alaska) = 40 PSF (please verify this with your local building department)

Dead Load (Metal Roof, trusses, etc.) = 15 PSF

Wood Species: Douglas Fir or Western Larch #1 or #2

5:12 roof pitch

Desired Header size: 4x12

Tributary length of the roof = 17.3 ft. accounting for the overhang and 5:12 pitch. This is computed by talking half the the width (14 feet) and adding the overhang (2ft) = 16 ft. The actual length of the roof slope is 17.3 feet accounting for the pitch. Therefore, the total load in PLF is 17.3 * (40 PSF + 15 PSF) = 952 PLF.

BeamChek computes the maximum distance between supports to be approximately 6-7 feet. Since your carport is 40 feet long, you may wish to go to 5' between posts, which is evenly divisible into 40 feet. This will be a super strong structure and should not collapse if properly built and secured.

Be sure to provide metal column brackets to anchor the header to the posts with bolts.

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