Pics of framing an overhang

Started by Don_P, February 16, 2011, 08:08:22 PM

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Don_P

I was working on framing the lookouts and fly rafter today and thought some folks might like a couple of pics of one way to do it.
The rake wall is built in this case 5-1/2" lower than the top edge of the rafters and braced plumb. The lookouts are then nailed to the last common rafter and project out over the dropped wall. Blocking is nailed between lookouts along the outside top edge of the rake wall.


I then measure the lookouts' overhang at top and bottom, mark it and snap a line down the row of lookouts. Then climb the ladder formed by the lookouts and trim each one to length, this assures that they are in a straight line. The fly rafter is then attached to the trimmed ends of the lookouts


From a bit further back;


This is where a porch roof will intersect so I ran the subfascia a little wild and then began installing bobtail rafters. We've installed blocking between rafters at the outside edge of the plate after the hurricane ties were installed. The blocking is a couple of inches below the top edge of the rafters to provide the ventilation channel. with the blocking in place the wind will not wash into the insulation low. This house may get foam, they aren't sure yet. If it does we will nail strips of plywood over the vent space and foam it solid.


While I had the camera out... this is cool. Ed our mason is using stone from the site to build the porch support walls, he'll do the chimney out of the same rock. A rubblestone wall is required to be 16" thick, we also have rebar in this tied to 12" anchor bolts into the porch floor sill. There is a plywood form wall on the backside which will be removed and he'll parge the backside with a trowelled finish. He is an artist.

MountainDon

That is nice stone work!   Framing too.

Just because something has been done and has not failed, doesn't mean it is good design.


Ernest T. Bass

Love the stone work, and those pics of the framing are really nice and clear/to-the-point. I've always thought that seemed like a great way to frame an overhang from a structural point of view.. Since I'm sure you've done it many other ways as well, could you share some pros/cons regarding the different common overhang framing methods? One project I assisted in, we built a separate ladder and tacked it on the gables.. It was a bit cumbersome and not real sturdy until the sheathing was applied. I guess it wouldn't be a greatest solution for a wide overhang, but worked okay for a relatively small one.

Can't wait to see more pics.. ;)

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glenn kangiser

Nice stuff - work and ideas.  Thanks, Don.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

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Don_P

Quotecould you share some pros/cons regarding the different common overhang framing methods? One project I assisted in, we built a separate ladder and tacked it on the gables

I've called that a hog trough. Your right it is not real strong and should be limited to very small overhangs or I've used it for a "faker" along the side of a shed dormer wall to make a matching overhang for the opposite steep pitch.

The next type that is very common is let in lookouts. These are notched into a rafter that is set just inside the wall line, extend back to the first common rafter like the ones I've pictured and out to the fly. They are ok for smaller overhangs or light snow loads. Since the lookout is flat it is weaker than the one I've pictured. To get a little more out of them you can use 2x6's instead of 2x4's and tighten up the spacing.

I saw we were getting several new members from heavy snow regions. If you are in snow country or have larger overhangs, the one I've pictured is the way to go. It can be vented by cutting notches about an inch deep along the top inboard edge or boring holes along that upper edge. If you are really going out there step back in another rafter bay, double that rafter and then go out. Although these are at 2' centers, I used my chalkline extended from a good distance back to straighten and align the lookouts every 4' so that they will be true and under the plywood seams. If you run those alternate ones at about 48-1/8" oc it allows for plywood clips, on a larger roof this will accumulate against you if you just run those at 48". This house will have 8 rows of plywood up each side so the accumulated error would have been significant enough that near the top I probably would haver missed breaking on the lookout... and there is the beauty of having them flat. But if you do miss break, it's all covered later, just add some blocking so that the edges are supported and keep running.


Ernest T. Bass

Thanks for the tips and insight, Don!

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