Roof Peak Connection

[JRay852]

I am working on a project that was stopped by the building department mid-construction. The owner is building a barn supported by posts/beams and cargo containers, without permit. I've been tasked with retrofitting the construction with additional supports to allow for the removal of all bearing on the cargo containers, but to keep as much of the existing structure as possible. The trouble I'm running into is particularly with the roof peak. The roof system is made up of I-Joists at 24" on center sloped at 2:12. The joists overhang a beam roughly 7'6" to the peak on each side. This creates essentially two structures that are connected through nails in the lapped flanges of the I-joist at the peak. What will it take to control the deflection and uplift in the overhanging roof members? I am thinking a tie at the top of the beams, at least for lateral displacement between the two sides of the structure but I'm not sure how to detail that connection to the I-joists. I would typically also look at a ridge board and collar tie for this type of connection, but with I-joist and such a low slope, I'm not sure how feasible that is. I've attached a detail to try and help explain the situation a little better. Any advice is appreciated!

 

[jayrod12]

Why are you sticking your neck out for an owner that didn't care to hire an engineer to begin with?

That being said, what about if at the peak you stuffed the gap between the I-joist webs with lumber and made it a real connection as opposed to one nail through each flange (which to me is questionable anyway).

Then, every other or every third joist you could consider putting a tension tie member between the top of the beams to control the outward thrust generated by this rafter configuration. You'll need to make sure that the I-joist connection to beam has enough capacity to transfer the horizontal load into the beam, then check that the beam can span under bi-axial bending between tension ties.

 

[JAE]

Can you add solid web blocking on each side of the ridge - and on each side of the I-joists - say about half-way to the beams - or to the beams.
Then add horizontal wood collar ties, lapping the blocking.

Also add a bent metal strap over the top of each I-joist, nailed into the top of the flange. Perhaps 24" lap on each joist on each side of the ridge?

I'd consider solid blocking between the I-joists over the supporting beams.
And perhaps a continuous board between the I-joists (a ridge board so to speak) at the ridge.

 

[JRay852]

I have looked at putting a ridge board, with metal straps over the top of the joists and a face-mount joist hanger to laterally support the joist through its depth. As the joists are lapped, should it be considered to use a wide metal strap with half the nailing in each joist, assuming I can reach the required capacity? I'd ideally line the joists up but as they've been installed, removing and reinstalling may cause unnecessary damage to the flanges. Along the same lines, a horizontal collar tie will not be parallel with the lapped joists. Maybe additional blocking on one side and a bolted connection?

Thanks for your input so far.

 

[jayrod12]

A ridge board is not required if you can ensure that the rafters are adequately connected. The original reason for a ridge board was just to facilitate construction, once rafters were up on both sides, it doesn't do anything. Like I said, pack the space between the two joist webs with wood. And then fasten them together robustly. This will do the exact same thing as a strap for the uplift forces, and will also ensure that the rafters can push against each other.

 

[JAE]

jayrod
I like the idea of a ridge board because it creates a longitudinal tie along the ridge line and also provides a continuous edge to allow edge nailing if the roof sheathing along the ridge.

Without it you have unsupported sheathing (diaphragm) edges at an area that has higher wind uplift forces.

I agree that for the I joist behavior the ridge board has only secondary purpose and value.

 

[oldinspector]

The I joist is an engineered product. (Maybe this no permit guy built them himself out of old phonebooks.) Make sure you get a copy of the I joist spec (companies have their differences) and see that it's acceptable for this use and design.

 

[JRay852]

Thanks oldinspector, I have manufacturer's specification and have verified the member capacity for this use.