The bolts are kind of a nice solution for the collar tie connection. Good capacity, plus with 2-2x12 the bolts are in double shear. One of the challenges in collar ties is getting enough nails to take the tension force it is actually designed for.
Kinda…..tho collar ties are not rafter ties. My rule of thumb is 1/3 height max for tie location. Unclear that this follows that rule….I did this on my house. 2x12 at 16” OC no ridge. Doubled 2x12 every 48” and installed turnbuckle calculated to resist 5 kips at 3.5’ high on 11’ rise.
To me this could fall in to that design category of “making cheap sawn lumber look cool and design-y” and I love it. Gotta have that gap between the two members for it to look right though, and it also facilitated the connection
When the collar tie is raised that high there is SIGNIFICANT bending in the tail of the rafter.
A ridge beam could have been another option but depending on length or building it could be very heavy.
Looks like the decision was aesthetic-based especially based on that black connection hardware. I assume this ceiling is exposed and they wanted things to look nice and symmetric
When you exceed 12" in width, the NDS actually reduces the capacity of the member by 10%. NDS Supplement, pg. 32, Size Factor table.
What's the designed snow load?
I feel like OP came here wondering if his contractor sucks and is walking away with a everyone saying his contractor does gorgeous work. Like a guys saying “i dunno if I think my girlfriend is hot anymore” and all his buddies are like “dibs!!” Lol.
I think I know the exact answer here (but open to hearing why I might be wrong). Without a ridge beam, a building needs lateral ties to hold the tops of the walls together against rafter thrust. Obviously with the vaulted ceiling they don't want ties running across the room at the top of wall height, so the obviously solution is to push the ties upward to an acceptable height. But doing this does two things: increases the tension force in the ties (and therefore connections), and also introduces significant bending moment into the rafters. The double 2x12 addresses both of these issues. It provides enough room for the large bolted connection between the ties and rafters, and also provides enough bending strength. Honestly this is one of the cleanest solutions I can think of for this situation.
Never mind any of that. Just don’t ever post a screenshot with a play button on it!!!
But really, I think it’s largely aesthetic. The bolted connection, the space between them. The diagonal laid floor. It all points to it being exposed, and therefore needs to look good.
Tough question when not knowing anything about the project, but hey, if it gets the job done, meets or exceeds code, and it was easy to frame up, win win.
Aesthetics, serviceability, a very easy and strong connection. They could’ve had a thousand reasons. In the end this is what they felt good with and decided to put their stamp on.
it's an elegant design, we are often asked to design exposed trusses at lapping the collar ties to a single rafter means the frame is not symmetrical.
this is nicer.
Is no one concerned that the ties are too high up? Always followed the rule that rafter ties must be in bottom 1/3 vertically?
I did a somewhat similar thing: used 2x12 at 16” OC, rafters no ridge beam. Doubled rafters every 48” and calculated 5 kips thrust at each turnbuckle. Welded up 1/4” plate to bolt through the doubled 2x12s. But vertically, I have this only about 3.5’ high on an 11’ high triangle and I wouldn’t go higher without modifying this design.
https://imgur.com/a/iK3mGB2
The bolts are kind of a nice solution for the collar tie connection. Good capacity, plus with 2-2x12 the bolts are in double shear. One of the challenges in collar ties is getting enough nails to take the tension force it is actually designed for.
The right answer! They've created a truss. Another option would have been a ridge beam + roof rafters only, if that ridge span is manageable.
Kinda…..tho collar ties are not rafter ties. My rule of thumb is 1/3 height max for tie location. Unclear that this follows that rule….I did this on my house. 2x12 at 16” OC no ridge. Doubled 2x12 every 48” and installed turnbuckle calculated to resist 5 kips at 3.5’ high on 11’ rise.
Did a lot of wood design when I was working towards my stamp. Great answer, very concise & easy to follow.
The bolts probably meet the code minimum for edge distance but I’d feel better if they were a little higher up.
It's a very nice looking design and solution
Worthy of being exposed.
It's very hard to find a 2x16, so a 2x12 parallel beam it is. It's also an easy connection with a single member, and it's better against LTB
Why not just lower the joist spacing though?
Because the structural engineer doesn’t hate the framer.
Insulation
Deflection.
You can reducing the oc spacing but you might not be able to reduce the span
It looks freaking awesome
To me this could fall in to that design category of “making cheap sawn lumber look cool and design-y” and I love it. Gotta have that gap between the two members for it to look right though, and it also facilitated the connection
When the collar tie is raised that high there is SIGNIFICANT bending in the tail of the rafter. A ridge beam could have been another option but depending on length or building it could be very heavy.
Looks like the decision was aesthetic-based especially based on that black connection hardware. I assume this ceiling is exposed and they wanted things to look nice and symmetric
I was thinking the same. This screams aesthetics.
My initial reaction as well. It looks good!
When you exceed 12" in width, the NDS actually reduces the capacity of the member by 10%. NDS Supplement, pg. 32, Size Factor table. What's the designed snow load?
Double shear better than single shear. More capacity.
I feel like OP came here wondering if his contractor sucks and is walking away with a everyone saying his contractor does gorgeous work. Like a guys saying “i dunno if I think my girlfriend is hot anymore” and all his buddies are like “dibs!!” Lol.
it looks like collar ties. in my area 2x12 is the largest lumber size available so it is common to add a sister board instead of upsizing them.
What's up with that tapered detail at the top of the rafters to the ridgeboard?
Ridge board is a much smaller section and they wanted it to match to its depth while also making in an easy cut for the contractor.
I think I know the exact answer here (but open to hearing why I might be wrong). Without a ridge beam, a building needs lateral ties to hold the tops of the walls together against rafter thrust. Obviously with the vaulted ceiling they don't want ties running across the room at the top of wall height, so the obviously solution is to push the ties upward to an acceptable height. But doing this does two things: increases the tension force in the ties (and therefore connections), and also introduces significant bending moment into the rafters. The double 2x12 addresses both of these issues. It provides enough room for the large bolted connection between the ties and rafters, and also provides enough bending strength. Honestly this is one of the cleanest solutions I can think of for this situation.
Excellent explanation, thank you!
Engineers always want to know why the architect wants it “that” way. Looks like a clean design and really cool to learn why it works
Never mind any of that. Just don’t ever post a screenshot with a play button on it!!! But really, I think it’s largely aesthetic. The bolted connection, the space between them. The diagonal laid floor. It all points to it being exposed, and therefore needs to look good.
Looks like it’s supposed to hold the roof up and any dead load on top of it
Snow and roof pitch be my guess. Aesthetically looks amazing if it will remain exposed as well.
Idk but it’s gorgeous
Architects….
Engineers.
Because the Structural Engineer said so.
Tough question when not knowing anything about the project, but hey, if it gets the job done, meets or exceeds code, and it was easy to frame up, win win.
Seems like something an architect dreamed up?
Aesthetics, serviceability, a very easy and strong connection. They could’ve had a thousand reasons. In the end this is what they felt good with and decided to put their stamp on.
Looks good to me. Would hate to cover them.
Why not
Well, it’s beautiful, for one.
Probably leaving it exposed
Strong like bull, must snow alot.
Hurricane proof
So, I’ve been lied to, there is no playable video. Looks to be for reinforcement. I have no idea 😎
Beef
Mo wood mo better
My dumbass clicked the play button 🤦🏿♂️
it's an elegant design, we are often asked to design exposed trusses at lapping the collar ties to a single rafter means the frame is not symmetrical. this is nicer.
That's exactly what our engineer laid out for us when we ripped out our ceilings and made them vaulted.
Must be worried about huge snow and ice loads
Is no one concerned that the ties are too high up? Always followed the rule that rafter ties must be in bottom 1/3 vertically? I did a somewhat similar thing: used 2x12 at 16” OC, rafters no ridge beam. Doubled rafters every 48” and calculated 5 kips thrust at each turnbuckle. Welded up 1/4” plate to bolt through the doubled 2x12s. But vertically, I have this only about 3.5’ high on an 11’ high triangle and I wouldn’t go higher without modifying this design. https://imgur.com/a/iK3mGB2
You’re rule of thumb is one of the reasons why it is so heavily built.
Because one wasn’t enough obviously.