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Can you tell me more about the span and spacing of a hammer beam truss?

Asked by Stephen on September 19, 2013

I was admiring the hammer beam truss and wondered what the span and spacing would be ? How many trusses would be required in building a 50 ft. x 50 ft house? or please give me some dimensions it would be best for. Thank you so much! Stephen

Answered by Doug Friant

Hi Stephen –

Thanks for submitting your questions about hammer beam trusses.

Engineerin-Q&A-Hammer-Beam-Truss

A hammer beam truss is a more intricate and complex truss compared to others but it has a great look. At this point in time all of the hammer beam trusses that we have done have been a custom design. The reason for this is that the roof pitch, span, spacing, species of wood and the location of the building can really affect the size of the timbers and geometry of the truss. With a 50 foot truss this would definitely be the case. As for truss spacing, I would say that a typical spacing would be 12 feet on center. At that spacing you would need 4-6 trusses, depending on if you wanted trusses on the gable end walls.

I hope that answers your questions!

-Jessie

4 comments
  1. Stephen Giddings says:

    Thank You! For answering this question. I am wanting to build ! I like the timber frame construction and you have beautiful designs!
    Stephen

  2. Doug Friant says:

    Glad to be of help – let us know when you are ready to build and we will be happy to get you started with a great timber frame design.

    Best,

    Doug

  3. Scott says:

    I would like to use 4″x8″ eastern hemlock for rafters. They span a distance of 12′ at a 9/12 pitch. Metal roof in a high snow area that requires 90 psi. I can not find any tables for timbers. Can you help?

    • Doug Friant says:

      Unfortunately, there is no easy table to reference. We recommend using a local engineer to size the timbers. The engineer will look at all the variables including drifted snow, dormers, dead load, etc. There is a slippery slope reduction you can use for snow load on metal roofs, but we almost never use it because someday a future owner may put on a different type of roof that isn’t so slippery. For simple rafter sizing we use an engineering program called StruCalc. It will get you close. My gut feel is that 4×8 is probably very small for a 90# snow load unless the rafters are spaced very closely. Good luck with your project!

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