Point load applied to roof diaphram

[UnneutralAxis]

A building I'm working on has had some changes per the architect. I now have a point load from a newly added wind girt that was never anticipated. I've looked and looked for a way to resist the girt's reaction of 4500 lbs from wind loading. Not that big, but something has to do it.

Load is applied at roof level. 3/4" plywood diaphragm. Would you feel comfortable just using a long piece of glulam blocking with a couple rows of 16d nails through the plywood into the top of the blocking to resist the load? I have up to 10' available for the length of the blocking. I have mono trusses framing perpendicular to the blocking... trusses are parallel to girt.

Any better ideas?

 

[UnneutralAxis]

I know this just sounds like a collector of sorts, wish I could show you the plans...

 

[a2mfk]

some kind of sketch would definitely help

 

[Lion06]

4.5 kips is fairly large for a wood diaphragm, depending on the length is distributed over. You'll need a lot of nails to develop 4.5 k.

 

[BAretired]

If you can't show a plan of the roof, show a crude sketch. Your problem is not clear at the moment.

BA

 

[msquared48]

A couple of MSTI60 straps could do that if properly positioned.

Again, a sketch would help.

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

 

[ToadJones]

Please DO NOT post the picture of that block wall again.

I was laughing so hard last night I couldn't sleep.

 

[UnneutralAxis]

Here is a quick, dirty sketch.

I am just concerned about putting that much of a point load into the wood diaphragm. There are openings in it for dormers about every 16' too to complicate things. Distance to wood shear wall from point load is about 16' horizontal.

 

[a2mfk]

If I understand the wind girt is for framing the end gable wall opening? Can you do a sketch of that elevation?

If I understand what you are trying to do, I don't think I like it.

I need more info to give you any helpful advice. For wood framing the architect is really trying to do a lot here... You may need some steel.

 

[ToadJones]

NOW THAT HAS ME LAUGHING
HAHAHAHAHAHAHAHAHAHAHAHA

Unneutral ...Thank you. That was funny.

 

[ToadJones]

Unneutral-
Can you put sway bracing in the lower mono trusses (in the plane perpendicular to your sketch)?
You should be able to transfer your load into the sway braing and back into the diaphragm.

 

[a2mfk]

Tear down that wall, Mr Gorbachev!

 

[ToadJones]

you may also be able to put sheathing on the backside of the lower monotrusses and make it a shear wall of sorts.

 

[UnneutralAxis]

ToadJones-
That was my original idea. It is a total pain because the state I'm in does expedited foundation/site plans for construction while the framing is being approved. Footings are already in. I don't have anything substantial enough below the truss to create a shear wall at the mono truss. I am hoping to get through this without a big change order.

Keeping it in the roof diaphragm is ideal. Your bracing idea in the monotrusses is something else I have considered and will likely include that too along with the strut.

a2mfk-
This is a gable end wall. There is no opening, just a half-@$$ed sketch. What isn't drawn is underneath the wind girt is a tall wood framed wall. An open stairwell is to the left side of the ridge. I posted about another tall wall a couple days ago, but this is a different situation. I haven't convinced myself that I like it either, that's why I'm questioning it.

 

[a2mfk]

What about using light gage studs or LVLs to full-height frame the gable rather than using the wind girt? Then you have a standard roof shear diaph. situation. That connection will be nasty to design at the end of the girt for 4500lb into wood, and I assume you will have to design for forces in either direction depending on the wind direction... Good chance your average framer would botch this no matter how nice and fancy your detail may be..

 

[ToadJones]

good idea- balloon frame the end wall to the top of the truss....or -3 1/2" from the top to allow for you rake ladder for the overhang as in a drop-gable truss.
I'd say 100% that is the way to go.
Set your last truss inside the balloon framed wall.

 

[UnneutralAxis]

a2mfk - I think you are right. I've spent several hours on details and it is just too detailed. A very critical component of the building and due to other items of the building (that I won't get into) would be very difficult to "observe" that it was installed correctly.

I appreciate the help. Usually the simplest approach is the best, I've found.

 

[ToadJones]

balloon framing will give you a nice flat wall too.

 

[ToadJones]

if balloon framing, be sure you install fire blocking, whether required by code or not.

 

[msquared48]

Yea...

You'll need the fireblocking to prevent the fire from igniting the helium-filled ballons. The results could be catastrophic!

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