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Roof truss weight rating

BubTheBuilder | Posted in General Questions on

I bought a house with room in trusses. My concern is about the structure of using this space as a bedroom or 2 as I have no idea what the trusses were designed for. The house is 24’ wide and 56’ long. Trusses are on 2’ centers and have a 2×8 bottom chord and 2×6 top chord. 10’ wide room in the middle. There are no diagonal struts, just vertical 2x4s for the 10’ wide room and one horizontal for the ceiling. Anyone know if this is sturdy enough for bedrooms, or can point me in the direction of someone who could help?

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  1. Zdesign | | #1

    Given its only a 24' wide truss it is probably fine for bedroom space which is rated at 30# live load 12# dead load. Best to check with a structural engineer or truss manufacturer though and have them run the calculations.

    1. BubTheBuilder | | #4

      I talked to a truss manufacturer and they don’t want to take responsibility one way or the other which I can understand. Just trying to prevent 3 steps forward and 1 step backward. Thanks for the response!

  2. Yupster | | #2

    Around here those are called "attic trusses", they are usually designed to provide a living space within the truss, so the truss designer would have planned for the appropriate live and dead loads. Also, the construction sounds pretty typical for that kind of truss (assuming it isn't a homemade truss. It has steel connectors binding the whole thing together right?). Doesn't sound like you need to worry about it.

    1. BubTheBuilder | | #3

      It does have the typical steel mending plates at all joints and the lumber used is tight grained and free of knots. Talked to a truss manufacturer and they don’t want to take responsibility one way or the other which I can understand. Thanks for the response!

      1. Expert Member
        MALCOLM TAYLOR | | #5


        There are a couple of ways you may be able to get an answer.

        Check with either the truss manufacturer or your municipality and find out who the designer was, or pull the permit set from the municipality. If the plans were sent to the truss manufacturer with the room drawn on them, or the municipality approved them with the room shown, they will say whether that space was designed to accommodate living spaces or just storage.

        I don't really understand where the truss guys are coming from. Their engineering must show what loading they used.

  3. walta100 | | #6

    From your question it is not clear to me. I am assuming you are looking at an attic space and considering making it into a living space. If that is correct I doubt the builder would have put the extra money into the structure. Budgets are always tight if they can save a few hundred and put it in their pocket they will every time.

    Will the ceiling collapse if you finish the room? Probably not.

    Is there an egress size window in the space? If not you could not call it a bedroom legally as it would be unsafe to sleep there.

    If you want a real answer you need to find the original truss manufacturer specifications. If that is not possible you would need to pay an engineer to look measure and do the math.

    Malcolm I can understand why a random truss manufacture would never comment over the phone on a safety question about a truss they may or may not have made given only the numbers from the first post.


    1. Expert Member
      MALCOLM TAYLOR | | #7


      I was assuming he was talking to the manufacturer that supplied the trusses. I can see how a general enquiry to a random truss plant wouldn't get a definitive answer.

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