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WILL1E
Moderator
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# Posted: 28 Jul 2021 08:41am
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Now that stick lumber is subsiding, i'm back to designing and pricing a stick frame design. The attached image is basically what we are shooting for (for sure a porch on the long side, not sure about wrapping around the short end yet...TBD). 16x30 is still our target size.
Anyways, since i'm 6'5" and my 14yr old son is already 6'2" i want to get as much useable headroom out of the loft. Planning on ~10' lofts on either end with a catwalk between the two. So i'm leaning towards 10' balloon framed walls with a let-in ledger around 8' high to support the loft joist. My question is how to frame the gable ends (is it called Gambrel ends if it's a Gambrel roof??) and how to do the gambrel rafters?
Since there will be a 1-2' high knee wall, i can't build gambrel trusses on the loft floor and stand them up like you would with platform framing. So i'm leaning towards getting a single LVL to span the 30' and then i can build half gambrel trusses and set them on the top plate and ridge board like you would a rafter.
The other question is framing up the gable/gambrel ends. Again, if i've got knee walls all around, and i frame the gable/gambrel ends on the loft floor, i would have to lift up the assembled frame on top of the knee wall and then stand up the wall without letting it slide off the top plate of the knee wall. So would i be better of making a temp structure to support the ridge board, set the half gambrel trusses on the end and then build the gable ends upright so there's no wall to lift?
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Steve_S
Member
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# Posted: 28 Jul 2021 09:02am
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Use this to work out building the gambrel framing, take your time.
https://www.blocklayer.com/roof/gambreleng.aspx
Balloon frame with Ledger is the simplest way to go, Nailing Rules apply, some inspectors would require "Structural Screws" and TBH that is wise.
The ends can be either stick built on the spot (pita) or if you run a plate across the framing you can do a pre-built filler..
I have seen several with 10' high wall frames, double Top Plate, Gambrel Roof installed on top of that. Remember that Gussets are quite important for rigidity. You can also built it with Running Ridge Board & Running Purlins(not common)
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snobdds
Member
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# Posted: 28 Jul 2021 10:42am
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We can tell you a million ways how to to it, but like all building, it will be determined on the fly. You can't plan for every little thing, you have to adapt and most importantly...you have to be willing to.
From all your posts, one can conclude you like to have everything planned out. That's fine, but never get bogged down trying to following a plan to the "T".
My gable end walls above the top plate was pretty straight forward, but trying to envision framing it all up in one piece was silly. We just measured and cut each stud to fit. It was faster in the long run. One person to measure and nail while the other cut the length and the angle.
If you don't do this a lot, you don't need to think like a production framer.
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WILL1E
Moderator
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# Posted: 28 Jul 2021 12:20pm
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Quoting: snobdds From all your posts, one can conclude you like to have everything planned out
That obvious eh?!  A 20+ year career in designing and fabricating parts with 3-4 decimals places of accuracy tends to do that to a person. That plus the fact that i refuse to hire anyone to do work for me is the reason my kitchen remodel took almost 2 years!
Sounds like i just need to frame all 4 walls up to 10'. Cut the let-in ledger for the lofts and then set the loft joist. Then build the gambrel frames on the 1st floor, use a temporary bottom chord and hoist them up in place and then build my gable ends in place.
I'll get some stuff drawn up and i'll come back for more feedback.
Thanks everyone!
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Brettny
Member
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# Posted: 28 Jul 2021 02:53pm
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Why cant you do platform framing with a knee wall? Why even put a knee wall on a gambrel roof? Or are you lowering the loft floor to below the top plate?
I have used the blocklayer.com gambrel calculator on a 19'wide gambrel roof on my shed and it worked well. How wide of a building is this?
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WILL1E
Moderator
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# Posted: 28 Jul 2021 03:03pm
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So the lofts will only be around 10' on either end. In my mind, given the gambrel roof will be exerting all it's forces outwardly on those walls, i saw balloon framing as the stronger alternative. If i platform framed on the loft floors, the knee walls would create a hinge point.
So yes, the loft floor will be 1-2' below the doubled up top plate. The distance is TBD yet as i'm trying to figure out what size joist i'm going to use for that 16' span. Also trying to figure out if i could use a gluelam at the edge of each loft, and then hang my loft joist perpendicular to that. This would cut the span down from 16' to 10' for those joists.
Building will be 16' wide.
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Brettny
Member
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# Posted: 28 Jul 2021 03:38pm
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So at best you will have a 6ft tall loft in the middle with a gambrel roof if you platform framed. Have you thought about making your building wider? Putting a wall in the center (or close to it) parallel to the ridge board would remove nearly any span issues even with a 20' wide building.
I dont think it's very strong or advised to put a loft below the top plate.
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Steve_S
Member
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# Posted: 28 Jul 2021 06:10pm
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Assuming 2x6 24oc Adv Framing with 10' walls, double top-plates. Rather than a Cut let-in, it likely would be more prudent to sister 8' 2x6 and set your loft floor joists that way sitting on top of the sistered 2x6. This would make it more rigid and tie the walls together. This not that uncommon for a building that is commonly referred to as a Storey & a Half. Maybe it's a regional thing.
A Gambrel Frame with gussets & a Birds Mouth for the top plates can work just fine and hurricane ties will lock it all in place. Gambrel by default is close to building, so little to no eaves & soffits. But if you play around with the blocklayer planner you can work it into the design and get the templates to make them. I spent 6 months deciding between Gambrel or Gable.
A Grambrel with Ridge Board can be built with the ridge board slot in place. Set the truss assemblies in place use 1x6 cross battens to line them up, drop the ridge board in place and nail it in. Use 3, 2x8's and Simpson plates to join them together.
REF: https://www.strongtie.com/trussplates_platedtrussconnectors/as20_tplate/p/as-20
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travellerw
Member
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# Posted: 28 Jul 2021 06:44pm
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I posted this in my roof thread, but thought I would bring it up here with a picture. It too am building a 16ft wide building. I played around with a gambrel roof and different sweeps and angles, but the one below seems like the best.
Sheathing seems to be tough without a lot of waste with those dimensions. No matter how you lay the sheets (verticle or horizontal) you are left with a 21"(ish) piece of panel. Which is not wide enough to fully cover the next section (would need an extra 5" piece). I'm not keen on using a small piece like that on a roof. That means %21 waste. You could use some of that waste for gussets, but that won't use all of it. Ordinarily, I wouldn't really care, but at $70 for a 7/16 sheet of OSB (1/2" ply is less at $65) its like flushing $30 every 2 sheets.
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Brettny
Member
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# Posted: 28 Jul 2021 08:30pm
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If it's just the roof we are talking about your also actualy throwing out almost 2ft of roof rafter too. Roof rafter you really cant use on the next course. If you do decide to use the 21in piece on the next course the piece left over after that is almost 4ftx4ft.
At 20' wide your rafters become quite a bit closer to 8' along with 12in more head room at the top roof, the top roof is also wider. I havent figured out the plywood spacing for 20' wide yet as I dont plan on building anything with even $40 plywood. Our roof will be metal with perlins. Shingles just dont stay good on the steep part of a gambrel roof and I see no reason to use plywood if I'm not going to use shingles.
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WILL1E
Moderator
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# Posted: 29 Jul 2021 08:27am
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Quoting: Steve_S Assuming 2x6 24oc Adv Framing with 10' walls, double top-plates. Rather than a Cut let-in, it likely would be more prudent to sister 8' 2x6 and set your loft floor joists that way sitting on top of the sistered 2x6. This would make it more rigid and tie the walls together.
I planned 16"oc for walls and 24"oc for the roof. Can you share a visual example of the sistered 2x6 with joist on top method?
Quoting: Steve_S A Gambrel Frame with gussets & a Birds Mouth for the top plates can work just fine and hurricane ties will lock it all in place. Gambrel by default is close to building, so little to no eaves & soffits. But if you play around with the blocklayer planner you can work it into the design and get the templates to make them. I spent 6 months deciding between Gambrel or Gable.
I was going to have the gambrel rafters be flush with the outside. Figured this would be cleanest for one side that will have the porch and for the other side i figured i'd cut separate rafter tails.
Quoting: Steve_S A Grambrel with Ridge Board can be built with the ridge board slot in place. Set the truss assemblies in place use 1x6 cross battens to line them up, drop the ridge board in place and nail it in. Use 3, 2x8's and Simpson plates to join them together.
I don't follow.
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Steve_S
Member
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# Posted: 29 Jul 2021 03:27pm
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Two pics;
Sistered studs with 2nd floor joist on top of sister stud.
Gambrel Roof highlighting ridgeboard (not ridgebeam).
Once these are spaced & attached to wall Top Plates and held stable with strapiing 1x6 or 1x4 (temporary on the outside, mid upper section) to keep alignment, then you can slip the 2x8 Ridgeboard into teh slot and nail it in place. Once all aligned and secured, remove temp strapping.
Not I show this with 24" gussets.
You can build the Gambrel "trusses" on teh ground or upper floor. If having to move them to lift & place, use a 1x4 or 1x6 attached 6" above the bottom edge to prevent that assembly from splaying out.
sistered_studs..png
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gambrel.png
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WILL1E
Moderator
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# Posted: 30 Jul 2021 08:18am
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Thanks for the illustrations Steve_S
I thought about doing the wall studs in that manner, but that's alot more studs. My other delima is i have ALOT of windows to put in, so my walls are going to be full of headers. I don't plan on their being much besides a bed and maybe a nightstand on each loft end, so not much weight will be up there.
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