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offgridengineer
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# Posted: 4 May 2025 01:00pm
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Need advice.
About to start the walls and roof. See picture. The ridgeboard 2x12 comes in 16' max. So it is not long enough to go end to end over the porch. Infact even without the porch, 16' plus overhangs is 18'. A friend told me to put the joins over the porch side wall. I feel there is no non sketchy way to do it.
How do you recommend I extend it.
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offgridengineer
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# Posted: 4 May 2025 01:01pm
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and that leaves me with a join at the back too, 1'.
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Brettny
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# Posted: 4 May 2025 03:18pm
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They come in longer lengths..just not typicaly at big box stores.
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offgridengineer
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# Posted: 4 May 2025 03:21pm
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Yeah, its from the sawmill. Everthing is rough cut. I struggled to move 16' lol.
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DRP
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# Posted: 4 May 2025 09:25pm - Edited by: DRP
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What you have drawn and describe is indeed a ridgeboard. I've bitten my tongue as what you technically need and what you are sensing you need, is a ridgebeam.
On the right side of your sketch the roof framing consists of pairs of rafters that have the heels tied together by the loft floor joists. That triangle is the simplest truss. As long as the connections hold a triangle cannot change shape. The ridgeboard is a convenience for framing but has no structural purpose, it is not required in that scenario.
The left side of the sketch is a whole different animal. The rafters, walls, floor forms a 5 sided assembly that is unstable. Push down on the roof and the walls blow out.
The correct way to frame a roof that has no rafter ties is to hang the rafters from a ridge beam. The beam is sized to carry half the weight of that section of roof and is supported at each end. In this case the rigid triangular truss at one end could be designed to support one end of the beam. Each side wall carries 1/4 of the roof load and the ridge carries 1/2, of that left half of your sketch.
Edit, here's the citation;
"R802.3 Ridge.
A ridge board used to connect opposing rafters shall be not less than 1 inch (25 mm) nominal thickness and not less in depth than the cut end of the rafter. Where ceiling joist or rafter ties do not provide continuous ties across the structure as required by Section R802.5.2, the ridge shall be supported by a wall or ridge beam designed in accordance with accepted engineering practice and supported on each end by a wall or column."
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MtnDon
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# Posted: 4 May 2025 11:39pm - Edited by: MtnDon
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Quoting: DRP The ridgeboard is a convenience for framing but has no structural purpose, it is not required in that scenario.
Further to that... just think of how a factory manufactured truss roof is assembled. There is no actual ridge board. Just a series of rigid triangles that are part of the structure. ... A ridgeBOARD can be a series of shorter pieces. The most important thing is the depth of the ridgeboard; ot must fully cover the cut pointy upward rnd of the rafters.
Re: the porch roof. As drawn it appears the outer left rnd of yhe porch roof is magically suspended. Perhaps the supports are just not included in that drawing.
Quoting: DRP The correct way to frame a roof that has no rafter ties is to hang the rafters from a ridge beam.
Yes. When we see old buildings with a sagging roof, that is often a result of the wall tops being pushed outwards because of insufficient or missing rafter tied and not because the ridgeboard was faulty.
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Brettny
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# Posted: 5 May 2025 09:27am
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I would try to re structure that framing to not use a ridge beam or board. Ridge beams at 16' tall above the deck are really hard to put up. Ridge boards are really just there for install ease. Build your sell trusses to tip into place. Doing this you will need something to tie the walls with no loft together.
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Grizzlyman
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# Posted: 5 May 2025 07:18pm - Edited by: Grizzlyman
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As mentioned the ridge board serves no structural purpose. You can just butt two of them together. You can put the butt joint wherever you want. I put mine right in the middle of the cabin above the loft.
Mine was 24’ long- so two 12’ joined in the middle.
I supported both ridge boards temporarily with a center post that was not structural. I put that on the edge of the loft. Then rested the ridge board butt on the post. You will want to make sure the joint is not between a pair of rafters.
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DRP
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# Posted: 5 May 2025 09:44pm - Edited by: DRP
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The pic below is just a sketch I had but it shows another way, a purlined roof. That could run from an exterior wall across to a several layer built up simple triangle truss.
Lifting the ridge... we don't know how big it is yet and I doubt a beam would be that large... need more info, but a pair of braced poles with pulleys up top and hand crank boat winches near the base is good for more than this will weigh. I've also built a temporary floor, tall sawhorses or even a big "box" we slid around just to get us safely where we wanted to be.
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