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Rafter to Ridge Beam Connection

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68K views 100 replies 24 participants last post by  XJCraver  
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#1 ·
We are building a screen porch for a client that has been designed by the architect with a double LVL ridge beam for the purpose of having a vaulted ceiling. I asked him how to connect the rafters and he said he's not an engineer and to look online for a prescriptive method.

Having never had to connect rafters to a ridge beam before, always done it in a ridge board scenario with collar ties, I'm trying to find a prescriptive way of attaching the rafters to the beam with no results I feel great about. Roof pitch is about a 5/12 and the porch is about 15' wide.

I don't know if nailing them the same way we do for a ridge board works or do I notch the top with a birds mouth for it to sit on the beam, etc...?

Any advice would be great. Trying to get this framed tomorrow.
 
#2 ·
You almost don't have to fasten rafters to a ridge at all, other than to keep them from shifting position before you get the sheathing on, when there are joists or collar ties to keep them from pushing the walls out.

Since you have a structural ridge beam that won't be pushing downward on the rafters, basically they are just serving as a bridge between the wall plate and the ridge. Just nail 'em like you're used to, and you should be fine.

Insert usual legal disclaimer here. :whistling:
 
#3 ·
Normally on a single ridge end nail the first rafter thought the ridge, toe nail opposing rafter, at least 3 on one side and 2 on the other with the proper degree. On that double lvl for nailing properly would pass inspection all day here. The ridge carries the burden.
 
X
#7 ·
As you described is our normal nailing pattern. With the double, as you said, we will have to do the 3 and 2 on both sides of the ridge.

Maybe I'm over worrying about how all these members affect each other and I'm not educated enough to understand it all yet. I would have thought that more than nails would be needed for there to not be outward forces on the top of the lower beams the rafters are sitting on.

Triple 2x6 on top of 6x6 posts for the "walls" since it's a screen porch.
 
G
#6 ·
I've seen a shaped plywood gusset and a bolt thru shaped steel plate to connect opposing rafters above a ridge.

Also seen a solid shaped plate to on top of the ridge to fill the space between the eafters and beam to provide nailing.

Pretty chitty answer from the architect to leave you hanging like that.

Submit a formal RFI describing the problem and state there is no detail for a connection and please advise how to proceed. Include the owners in the RFI....

They paid the SOB for plans he should provide them....
 
X
#11 ·
Yeah but you live in California so I can't take answers from you. :laughing:

All jokes aside, I'm assuming the code is worse for you guys out there because of seismic issues right?

Architect is a mutual friend of mine and the client. I was surprised at the answer I got but it sounded outside his scope to provide that info I guess. We don't have much experience working with architects and engineers.
 
#10 · (Edited)
The rafters should properly sized for the load, taking into account
That no collar ties will be used. What would a Simpson tie or the like do in the event of a sagging ridge? The walls would kick out first.

I've used steel, steel/wood hybrid ect , scissor trusses, a lot of options depending on details.
 
#13 · (Edited)
I'm actually certain most inspectors would want to see some kind of connectors in this case thinking about it. Part of the reason for collar ties is to keep the roof from seperating in the event of a very strong storm.

Every circumstance is different. As far as structure the nailing works fine. Has forever and ever
 
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#22 ·
I have done them with and without hardware. We have had a few where nothing was called out, and we just nailed them like we would any other rafter. A ridge beam is sized so that no collar ties are needed, and as long as the rafter is properly sized, you are good to go. Probably a good idea to provide some kind of straps to the post/ridge connection, as well as the post/slab connection.
 
G
#25 ·
I'd like to respectfully disagree with everyone. There are not gravity forces holding them to the ridge that happen when you have rafter ties or CJs.

In a vaulted ceiling, rafters are essentially the same as a floor joist. You wouldn't just toe nail those to the face of a beam. You would bear those on a beam, a plate, or a joist hanger, wouldn't you?
 
#35 ·
Just look at TABLE R602.3(1) FASTENING SCHEDULE Item #7

Toe Nail
Roof rafters to ridge, valley or hip rafters or roof, rafter
to minimum 2″ ridge beam: 4-16d (3 1/2″ × 0.135″ ); or
3-10d common (3 1/2″ × 0.148″
); or
4-10d box (3″ × 0.128″ ); or
4-3″ × 0.131″ nails
----------------------------------------
End Nail

3-16d box 3 1/2″ × 0.135″ ); or
2-16d common (3 1/2″ × 0.162″
); or 3-10d box (3″ × 0.128″ ); or 3-3″ × 0.131″ nails
 
X
#36 ·
Well we got everything up today. Toe nailed 3 nails one side, 2 the other, and 1 through the top of the rafter into the ridge. The inspectors here are very lax usually and I'm not expecting an issue. If there is one, I'll be reporting back I guess.

Thanks for all the answers guys. I appreciate the feedback and the dialogue on the issue.

Image
 
G
#46 ·
Here a PE talks about everything in this thread, including wind uplift, how CJs on a ridge beam don't have outward thrust and are designed as a simple bearing beam, and a lot more:

http://www.structural101.com/Structural-Ridge-Beam.html

I'll repeat, toenailing in this case is like toenailing floor joists. Probably fine, but we all know it's not quite right especially with bigger loads.
 
#55 ·
Golden view said:
I'll repeat, toenailing in this case is like toenailing floor joists. Probably fine, but we all know it's not quite right especially with bigger loads.
Click to expand...
I think the exact comparison would be toe nailing shed roof rafters to the side of an existing structure, except the ridge beam gives you a lot more to nail to than a 1" board. The big issue is either a wind event or, if the foundation moves and the wall starts kicking out at the top, it can pull the nails over time.

IMO, making sure you have a good foundation and putting the straps in place are at the top of the list, from there you're talking safety factors beyond code requirements, which have accepted safety factors built in.
 
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