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Gable end wall
2

Gable end wall

Gable end wall

(OP)
I have three questions concerning gable end walls:
1. What's the advantages and disadvantages of (a)framing gable end walls with gable end trusses on top of flat masonry walls and (b)with triangle masonry gable end wall with concrete rake beam on the top?
2. Of (a) and (b) in question 1,which is more commonly used in practice?
3. If gable end wall is framed with (b),how is roof sheathing connected to the rake beam?Where can I find a detail of this connection?

RE: Gable end wall

The attachment of sheathing to a cmu wall is usually accomplished by fastening a ledger beam or treated wood plate to the wall.

Donald Breyer's "Design of Wood Structures" has examples of this detail.

RE: Gable end wall

1.  Its probably cheaper and quicker to use a gable truss.  

2.  Ususally the gable truss - but I have seen both

3.  I concur with RARSWC and the book is GREAT!!

RE: Gable end wall

2
1.a. Gable end truss is simpler.  However, gable end trusses are not designed for the out-of-plane loads they receive.  In addition, your masonry wall is not braced at the top by the truss or the ceiling so you have to add bracing or design the masonry wall to cantilever.  That gets messy.

1.b. The wall is well supported at the top by the direct connection to the roof diaphragm.  You eliminate the hinge you put in the wall where the gable truss meets the top of the masonry wall and therefore don't need a bunch of bracing.  This is more expensive however.

2. I see 1.a. used most often, but the bracing still doesn't address the out-of-plane loads on the members of the truss.  The other option is to eliminate the gable truss and design a stud wall.  That takes care of the wind but you'll still need to brace the top of the masonry or design it to cantilever.

3.  You can leave the top of the raked concrete beam down 1.5" so you can put a continuous wood plate or a ledger to provide nailing.  A ledger may not require the raked beam to be left down.



RE: Gable end wall

A lot depends on the ceiling height.  If a flat ceiling, then you will see the gable truss and associated bracing.  If vaulted ceiling, then you see the raked wall.

RE: Gable end wall

SSTD-10 has a nice detail of masonry rake beam

RE: Gable end wall

Fact a lot of people may not know: Gable roofs use more material than a hip roof when manufacturing trusses. Only savings comes from labor by reducing the number of truss configurations.

On top of this, with the addtional plywood needed on the gable face, and the amount of "X"-bracing, hips are cheaper in the long run. May reason for gables that I see are vaulted ceilings that cannot be hipped over, or the demand for attics. As a truss designer, I would not want gables on my house.

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