There are many styles of homes that are built with
gable roofs. It is the simplest roof of all to frame. It is also the
most common roof built for that reason alone.
All the rafters cut for a gable roof are all cut to the same length. The
birds mouth, which is the cutout that sits on the top plate, is located
in the same place on all rafters. The overhang, if there is one, is also
the same.
The ridge board, which is usually a 2x, runs the full length of the
house. This can be cut ahead of time and have the rafter layout marked
on it. The rafter layout usually matches the wall stud layout. This
transfers the roof load down to the foundation.
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Before any framing begins, some of the plywood that will be used for
roof sheathing is laid across the ceiling joists the whole length of the
building. This gives the carpentry crew something to comfortably stand
and walk on during the construction of the roof. It's also a good idea
to pass all the roof plywood up to the ceiling joists. This makes
passing it up to the roof much easier.
Next, pass the ridge board(s) up and lay them on the plywood walkway,
making sure the layout is going the right way and matches the wall
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Now pass the rafters up. Lay them with the plumb cuts on the
plywood and the tails on the top plate. If the house is a ranch, the
rafters can be leaned against the wall between ceiling joists to keep
them from sliding of the wall. Send up a couple of 2x4's for bracing and
you are ready to frame.
Before the ridge board is even raised, nail two rafters to one side,
nailing on the first one and the last one on the layout. The ridge can
now be raised. Pull the ridge so the birds mouths are tight to the wall
and raise it high enough so the level cuts of the birds mouths are flat
on top of the wall. Once the rafters are in place tack them to the wall.
Now nail two rafters on the other side of the building to the top plate.
These will also be the first and last rafters on the layout and will
mirror the ones you put up on the other side of the building. Raise or
lower the ridge so the top of the plumb cuts on the rafters meet the top
edge of the ridge. If the rafters where cut correctly, the plumb cuts
should fit snugly against the ridge with little or no gaps.
With the ridge in place, install a stud in the gable end from the ridge
down to the top plate, using a level to plumb it up. Take one of the 2x4
braces and nail it near the top of the stud. Nail a block to the plywood
walkway being sure to catch a couple ceiling joists. Now put the level
on the 1 1/2" side of the stud and plumb it that way. When the stud is
plumb, nail the 2x brace to the block. This will square up and position
the roof where it needs to be. The rest of the rafters can now be
installed, alternating from one side to the other, pulling the rafters
tight to the wall and bringing the plumb cut to the top of the ridge. By
alternating from one side to the other the ridge will stay straight. If
one side is installed all at once, the weight will push on the ridge
creating a bow. This will make it tough to straighten when the other
side is put on.
After the roof is framed, collar ties, fascia boards, and overhangs are
put on. With those items in place, the plywood can be put on. Frame in
the gable ends and your ready for shingles.
Mike Merisko (c) 2006 www.sawkerfs.com
About the Author: Mike Merisko has been a carpenter for 26 years. Most
of those years were spent in the homebuilding and remodeling industries.
He was also in business as a carpentry and general contractor. While
that is his forte, he also has experience in bridge building, commercial
construction, and exhibit building which is how he earns his living
these days. You can browse through articles by him and others at his
website http://www.sawkerfs.com or visit his blog at
http://www.sawkerfs.blogspot.com
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