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jessica562

wood i-beams for roof?

jessica562
10 years ago

My contractor wants to use wood i-beams for our roof but the architect's engineer is not a fan. He says that too many contractors install them wrong and need to get field updates on the engineering. Our contractor says that this is a good place for us to save money since we have a simple roof line with long spans. Does anyone have an opinion on this? Should we go ahead with the ibeams and have the manufacturer provide engineering stamp?

Thanks for your input...

Comments (8)

  • millworkman
    10 years ago

    As long as the roof is properly engineered there is nothing wrong about using Wood I's for rafters. It works very well for as you described long spans but it becomes even more critical that the installation guidelines are followed to a tee and that the builder has a firm handle on this type of installation.

  • GreenDesigns
    10 years ago

    There's nothing wrong with I beams if they're done correctly. We used them in our recent sunroom to living space conversion. They spanned the 30' distance and opened the space up well. Now, we did have to plan for the support at either end, and your architect and contractor will as well. Perhaps it's time to lock them both into a room in a cage fight and let them work on the plans together. Having you be in the middle of things probably isn't contributing to good communication between them. Let them get on the same page and then communicate the solutions to you.

  • PRO
    Epiarch Designs
    10 years ago

    I Joists are just fine. I used them in my vaulted space due to the span vs solid lumber. Plus I wanted them 14" deep for insulation reasons. Now typically you will need a ridge beam vs a trussed roof. There are bearing details that need to be followed that include limits on how the foot can be cut, and if web stiffiners need to be installed. I assume since they are suggesting it, he is familiar with the installation requirements. However depending on the span, I can not see how they would be cheaper than solid lumber, assuming that is the alternative. (they are straighter, lighter, and stronger than solid wood which could be their reasoning as well)

  • virgilcarter
    10 years ago

    Is your roof pitched or flat?

  • renovator8
    10 years ago

    The relevant issue is the bearing and bracing details which are more complex for sloping i-joists. Carpenters who don't read the detail drawings carefully often make mistakes which is why the engineer is not a fan.

    Apparently, neither he nor the manufacturer is in a position to observe and, if necessary, reject the work so you should respect his concerns and find a way to deal with them.

  • jessica562
    Original Author
    10 years ago

    Thanks for the input...The roof has a very low pitch,(1-12 I think) and will have a metal roof. We are going to have the final plans drawn with conventional lumber and let the contractor price it both ways. Personally I want to use the i-beams but final decision is pending.

  • virgilcarter
    10 years ago

    If you have a 1:12 pitch and propose to use metal roofing, you are heading for big leakage troubles. A pitch of 4:12 is about the lowest for dependable performance for metal roofing (or shingles of any material)

    Less than 3:12 pitch generally means a continuous membrane or built-up roofing system.

    Big difference.

    Good luck with your project.

  • dadereni
    10 years ago

    There are some commercial metal roof systems or soldered seams for very low slopes but that's probably not the appearance you have in mind.

    This post was edited by dadereni on Thu, Jul 25, 13 at 17:22

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