Wood Framing - Ridge Beam Supports

[Eldorado]

I am trying to figure out how much load I should design ridge beam supports for. Actually, I'm more concerned with the reaction of the ridge beam support on the next framing level below. For wood framed structures with standard rafters, ceiling joists and a ridge beam, our office supports the ridge beams at approximately 11' to 12' spacings. We run the ridge beam support to a wall, float beam or ceiling beam. If you believe that the ridge supports are needed, does anyone have a rule of thumb as to how much load the supports should take.

 

[msquared48]

Sorry, but a generalized question gets a generalized answer.

The supports for the ridge beam need to support the ridge beam loads, so whatever the ridge beam reactions are are what the column(s) support. It's that simple.

It sounds like you might be insinuating a collar tie condition, though it's hard to tell here. A diagram might help.



Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[csd72]

Whatever design assumptions you make for the design of the roof need to be consistent throughout the building.

If it is a load bearing ridge beam then the full loads need to be transferred down to the foundation.

If it is not designed as load bearing then it is purely a serviceability and strain compatability issue that needs to be considered.

 

[Eldorado]

Thanks csd72, the ridge beam is not a load bearing ridge condition, so your comment regarding strain compatibility is the more appropriate condition I'm interested in. We do a high volume of residential structures. I know this is a generic question, but what kind of review/analysis would you consider reasonable for the ridge support discussed. I don't want my ridge support causing excessive deflection at the ceiling beam I use to pick it up, but on the other hand, I don't want to keep design the ceiling beam as if it were picking up load from a structural ridge beam either. Thanks in advance for any guidance you can provide.

 

[msquared48]

If it is not a load bearing ridge beam, then this must be a collar tie or truss condition?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[csd72]

msquared48,

Agreed.

Eldorado,

Are the ends of your joists tied in against lateral spread?

 

[Eldorado]

Yes, the ceiling joists go from one end to the other (plate to plate) at each pair of rafters and keep the rafters from lateral spreading. Additionally, collar ties are installed in the top third of the framing at 48" centers, but I only rely on these to address rafter separation from the ridge beam due to wind uplift. I interchange my collar ties with Simpson straps centered over the ridge, but mostly with vaulted ceilings.

Generally, I refer to a "structural" ridge beam as one that supports roughly half the load between supporting wall lines (simply stated), such as a vaulted ceiling with no lateral spreading restraints at the plate lines.

 

[csd72]

Eldorado,

Yes, we are thinking along the same lines then. I would just make sure that there are no stiff walls under the ridge beam that may accidentally act as a support.