Gable end support
Gable end support
(OP)
I have read the posts in Thread #507-240778 ----Which was “Gable End wall support.” It is now closed. There is one post in there that reads in part as follows”
“I have been asked by a contractor to engineer a wood garage. The plan dimensions of the garage are 40'-0" x 60'-0" (clear span) with a required clear height of 16' and a 8:12 roof.
The only problem I can't resolve is how to transfer the loads from the gable ends into the wood roof diaphragms.
I could sheathe the underside of the trusses with plywood (gypsum board is not strong enough) but I don't think the contractor would like that. I could provide kickers at 2'-0" o.c. but I am not sure if this is the best way to go.
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I have used a variety of systems to achieve support for the gable ends of such buildings and I’m not exactly happy with them. I have sometimes strapped the ceiling for light gage metal covering in shops. The strapps but into the gable plate. And sometimes I sheeted the ceiling (when the owner would agree)
I like the strut idea described in several of the posts which uses the Simpson GBC connectors at the double plate of the wall. I am wondering how the top of the strut might be attached to ensure load transfer into roof diaphragm (7/16” OSB). Would it be attached to the upper chord of a single truss? Or may to blocking between several upper chords.
“I have been asked by a contractor to engineer a wood garage. The plan dimensions of the garage are 40'-0" x 60'-0" (clear span) with a required clear height of 16' and a 8:12 roof.
The only problem I can't resolve is how to transfer the loads from the gable ends into the wood roof diaphragms.
I could sheathe the underside of the trusses with plywood (gypsum board is not strong enough) but I don't think the contractor would like that. I could provide kickers at 2'-0" o.c. but I am not sure if this is the best way to go.
***********************************************
I have used a variety of systems to achieve support for the gable ends of such buildings and I’m not exactly happy with them. I have sometimes strapped the ceiling for light gage metal covering in shops. The strapps but into the gable plate. And sometimes I sheeted the ceiling (when the owner would agree)
I like the strut idea described in several of the posts which uses the Simpson GBC connectors at the double plate of the wall. I am wondering how the top of the strut might be attached to ensure load transfer into roof diaphragm (7/16” OSB). Would it be attached to the upper chord of a single truss? Or may to blocking between several upper chords.






RE: Gable end support
DaveAtkins
RE: Gable end support
RE: Gable end support
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Gable end support
The problem with balloon framing was that the studs were too large and everyone who I run into want to use a gable truss on the end. The stud at the ridge wold have been over 25 feet tall in this instance. I have asked others about the problem and they seem to use some form of bracing in the gable end.
There garage is still there after a few hurricanes, blizzards and a snowy winter.... that's all I really care about.
RE: Gable end support
I know what you mean. I have insisted on sheathing the ceiling a couple of times. And all I hear was how "they have never done this before" and how I was "being too conservative” etc. Contractors all want to use a gable studs on the end. And of course they need to use some form of bracing at the intersection between the gable studs and the regular wall studs below. The roof trusses need to take care of the brace reactions.
I think I will use full length LVL . If we do it the other way it is possible they may have a problem before they get the ceiling sheeted … or maybe even not bother sheeting the ceiling at all.
RE: Gable end support
These types of building are always a problem. Trying to get the numbers to work out on adding braces at the ceiling line is tough and expecting it to be built correctly is wishful thinking. Ironically, the buildings, even designed and built poorly, seem to hold up well.
RE: Gable end support
RE: Gable end support
Here is a link to information on structural finger-jointed lumber: http://www2.wwpa.org/TECHGUIDE/FingerJointed/tabid....
RE: Gable end support
RE: Gable end support
Excel - you seem (maybe not) to be against the use of bracing at the ceiling (kickers up to rafters/roof deck) - have you seen cases where this has caused problems? I feel like I have seen this constructed a few times but don't remember hearing/seeing any issues (disclaimer - I could be wrong here and I don't have a ton of experience). Also no apparent strengthening of the truss that I can recall either. Just curious, Thanks!
EIT
www.HowToEngineer.com
RE: Gable end support
If you run the numbers on the uplift loads on the truss it get pretty hard to design. Also, unless you run the kickers at a really steep angle to the first truss, there will always be a web in the way. If you try to run a really steep angle, the numbers get huge. I have never seen one built correctly, even though they seem to work.
No free lunch here. The best way to react these things is horizontal. Even trying to detail a horizontal truss to brace it is tough as the numbers get big and there is a bunch of detailing.
RE: Gable end support
EIT
www.HowToEngineer.com
RE: Gable end support
RE: Gable end support
As a side note, an agricultural barn I designed a couple years back I used sheathing 8 feet into the building on the bottom chord with blocking and diagonals. We had an extremely large wind load come up during construction. The neighboring farmer was having a similar structure being built but apparently wasn't engineered (not sure, I wasn't around to verify) and didn't have the bracing. The building I designed survived, the other guys ended up being a pile of tooth picks.
It seams it is a toss up whether doing all the bracing, or increasing the size of your studs, is the most cost effective option. I've done both.