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How to hang trusses below top plate of bearing wall

Moko21's picture

I'm working of a set of concept drawings for a new house in Phoenix before I hire a designer to polish and finalize them for review with the city.  I'm stumped on an element of the design regarding hanging trusses and can't find a solution.  I hope someone can help.

The house will have flat roofs and the area in question has two ceiling heights (11' and 13') and two corresponding roof heights (13' and 15') on either side of a 13  foot 2x6 bearing wall.  The 2'x25' trusses for the higher ceiling/roof will sit on the top plate and how they are attached and braced seems pretty clear.

What's not clear is how to hang the 2'x25' trusses 2 ft down on the bearing wall to result in a ceiling height of 11ft and a roof height of 13' on the other side of the wall.  I could use slightly taller trusses with a load point on the top chord but I'm concerned the drywall joint between the ceiling hanging on the bottom of the trusses and the wall will have problems over time as the trusses shrink and expand.

Can I simply attach a couple 2x8 plates to the wall and hang the trusses from them with standard truss hangers?  I've not seen a description in the IRC how this plate attachment to the load bearing wall is to be spec'd nor have I found a hanger to reinforce the attachment of the plates to the wall.  Just nailing them doesn't sound like it would be adequate.  What's the best solution?

Thanks,

Tres

Lower the bearing wall? (post #207369, reply #1 of 9)

Is there a reason you can't have a shorter bearing wall under the lower trusses?

 

If the design mandates a taller  bearing wall, the truss company will specify how to attach them - possibly with a top chord bearing truss.

 

Terry

Lower the bearing wall? (post #207369, reply #2 of 9)

I was hoping to avoid the cost of the second bearing wall.  The top chord truss option seems to beg for problems with the joint between the ceiling drywall and the drywall on the wall.

moko (post #207369, reply #3 of 9)

If you can figure out the connection-lower the wall, install the lower trusses, stack and secure the higher trusses on top.

If it's street legal, I don't suppose it'll alleve your concern of movement and cracking of drywall. 

Instead of worrying about it-utilize it in the design stage and dream up a suitable cover.

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You know, you could always (post #207369, reply #4 of 9)

You know, you could always use a different treatment of the ceiling joints, and alleviate your worry.


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I did a building that had a (post #207369, reply #5 of 9)

I did a building that had a similar situation. As I recall, I let-in some 2x material into the higher stud wall, sheathed (this was an internal wall but also a shear wall), then used Simpson hangers to hold the (bottom chord bearing) flat trusses. 

You can use ledgers, but you (post #207369, reply #6 of 9)

You can use ledgers, but you have to engineer the connections. If bolting is not practical due to the load you could also look at partially letting in the ledger. This is not a connection you should design yourself.

A few thoughts, shooting from (post #207369, reply #7 of 9)

A few thoughts, shooting from the hip.

The higher truses could be TC bearing, as you mentioned. If they're only 2' deep they won't change enough in depth to cause any drywall problems.

A ledger could work O.K. if it was engineered. The connection to the wall would have to be specified.

You could build a shorter wall and see the lower trusses on it.  Put a 2x plate on top of those trusses and set the upper trusses on top of the plate.

The end vertical on the upper trusses could extend down 2' and sit on a shorter wall.

 

You might also consider sending the preliminary design to a truss manufacturer for suggestions. We deal with stuff like this all the time, and most places are happy to help. I prefer to head off a problem in the planning stages rather than deal with it when there's concrete in the ground.

how to hang trusses (post #207369, reply #8 of 9)

Sounds to me like you'd want to attach the trusses to the bearing wall with a ledger and hangers. I'd hire an engineer to design the connections if I were doing it.

Engineering (post #207369, reply #9 of 9)

I think your best avenue is to have the truss engineer look at how the truss will be installed.  He/She will either design a connection, or have you take it to a structural engineer.  Either way I'm pretty sure the City will want the connection engineered.