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Ladder rafters, fly rafter, look-outs

John Klingel | Posted in Mechanicals on

Whatever name you prefer, I have a question on how far they are allowed to extend out vs how far they extend back into the attic. I am of the understanding that the ratio is 1:1. A “normal” gable end stick-out is often 2′, so the first truss, to which said ladder rafters abutt, should be inset 2′ from the gable truss. It is my understanding that this “balance” will prevent lifting of the first truss if, say, the ladder rafters instead stuck out 4′ and back in only 2′. (Gable truss is the fulcrum.) If 1:1 is the recommended ratio, how far can you push that if you assume a 30-40 psf snow load? 1.5 out to 1 in? 2 out to 1 in? We will assume that the supporting member (fly/ladder rafter) is strong enough to hold the load. All I am concerned about is the ratio of stick-out to stick-in. Thanks.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    John,
    It's time to consult an engineer.

  2. John Klingel | | #2

    Thanks. I did, but wanted a second opinion. He said 3:2 was pushing it, and would probably work, but would not bet on it. That is probably reality.

  3. John Klingel | | #3

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