Intersecting Double Ridge & Valley Beam Connections

[UnthoughtKnown]

I've been tackling this issue for a while now and have had some discussions with builders regarding these connections.

Best way to start this discussion is to view the following video:

http://www.askthebuilder.com/Valley_Rafter_Video.shtml

I'm set on using Simpson Hangers for this application, but most framers refuse to believe that the sloped and skewed hangers are really necessary and if they can be installed properly. Truth is they are difficult to install, it's tough getting all the nails in properly, etc. This is due to framers wanting every cut tight and believing that the sloped roofs are leaning against each other and that they act like a wedge. I agree it's good to do this, but as engineers we have little to hang our hat on to determine safe capacities based on the wedge action and toe nails only.

I know Simpson also makes the Multiple Seat Connector, but try and sell that to a residential framer, and they have limitations.

I wanted to get thoughts on how you believe this is truly behaving and if it is too conservative to try and deliver the reactions as if it was a flat roof.

Thanks......

 

[ToadJones]

I dont know what you are asking, but I'm gonna put down my engineering hat and pick up a hammer here....
this type of framing time tested.

 

[woodman88]

To determine the safe capacity you would have to consider the roof sheathing nailing with the wedge action and toe-nails.
The biggest problem, IMO, is that when the hip rafters are just nailed they are less safe than hangers until the roof sheathing is applied. (Unless they are all supported during construction properly.) And without the roof sheathing the ridge beam would not be laterally supported to resist the wedge action.
Once the sheathing is applied, than for normal spans, I am okay with the nailing. I would note on any detail the maximum span and that the ridge and rafters be supported (vertically and horizontally) until the roof sheathing is applied in bold, enlarged or underlined letters.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[UnthoughtKnown]

Toad Jones - that's what I'm talking about and the type of response from framers.

Up to what size roof do you think it's OK to do it traditionally?

What if the main ridge is 30' long and the intersecting ridge is 16' long and the snow load is 40 PSF?

 

[ToadJones]

I dont see the wedge action unless the rafter is held laterally in place at the connection.
I guess you'll have to run numbers to see what capacity the connection has sans the plate connectors.
I have never used a sloped skewed connector for hip & valley framing.
As Garth alludes, the sheathing overtop the rafter onto the hip/valley/ridge also adds capacity.
Nailing hip & valley rafters is actually easier than a normal ridge, IMO.

 

[idecharlotte]

We brace all hip/valley/ridge intersections with a double 2x6 'T' down to a beam or bearing wall. On top of the brace is a flat 2x10 or 2x12 piece that catches all the members. In the event that you cannot brace, the"wedge" action creates a thrust on the walls that you would need to design for. You are really relying on the frictional force created by the compression and the shear force from the toenails to hold it together in that case. That can be a pretty good connection on a small, light frame. However when we need something more substantial Simpson connectors, Timberlok screws or plates and bolts are required to hold the connection together. We would only require that for large vaulted ceilings framing into a bent beam or truss. Otherwise we brace it.

http://www.idecharlotte.com

 

[UnthoughtKnown]

Thanks IdeCharlotte for your response. It seems like you are in agreement that something needs to be specified for larger spans.

Anybody else have any input or experience with the Simpson skewed and sloped hangers?

 

[msquared48]

I specify skewed hangers all the time, but seldom sloped, preferring flat bearing and notching of the rafters/beams for flat bearing in the seats.

More work for the framer, but it makes the connection more stable until the sheathing is applied.

Mike McCann
MMC Engineering