I would like to have 2ft of overhang on my gable ends to keep the rain/snow away from the cabin walls. Can i do 2ft of overhang with just the boards of the roof? or would it need support?
Thanks
Sbishop
Depends, on a lot of things, like roof snow load and the thickness of the boards.....
Jim, here's more details
roof will be a 8/12 pitch, boards will 1" t&g and oh ya....lots of snow here ;D
Sbishop
Sbishop,
There was a thread here a while back on if you have rafters every few feet you can push it a bit and have you boards overhang horizonatly, but 2 ft is a bit much w/out returns
I used purlins and I have 3 foot of overhang for my straw bales. What I did is put pockets in both sides of the rafter (8x10) with a 1.5"deep dado running between the pockets. I then notched the purlins (6x7)so that they ran in the dado but shouldered out in the pockets.
It is at this point so far. I plan to hang a 2x10 "barge rafter" Some might call it a a fascia board to connect all the purlin ends toogether running up the rake. I hope that all of the purlins acting iin concert will handle the load. I may need to run a return back to the bale walls, which will obvously be easier if you have a more conventional wall.
I cant vouch for the longevity of this design but it appears sound to this point. My computer has been down for a bit and my photo edit software is AWOL, but I will try to get some pics here soon if you want.
I am planning on using 2x8 (rough) for common rafters. if 2ft is too much wihout support maybe i can extend the last row of logs on my walls so i can put a rafter on the outside the rear gable end...the front has a covered porch so there will be support
18" is the limit for 2" thick t&g in the tables I checked here, and it had load limits based on species and grade.
I think you'll be happier with a barge/verge/fly/fascia board at the outboard end of the boards supported from either below or above. I usually frame a "ladder" over the wall with blocking framed every 2' perependicular between the fly and the first inboard common rafter.
One of my drawing programs automatically puts in framing based on the user's input. Here is a shot of a simple 8/12 roof with 2' over hang and 2x8 rafters 24" oc with the ladder which DonP has mentioned.
This program puts the ladder pieces in flat, and I'm not sure if that's the way it's done or if they are vertical. But this type of ladder assembly will help support large gable overhangs.
(https://forestryforum.com/gallery/albums/userpics/10095/Lookoutframing-2.jpg)
Jim, i've seen that setup in the books i have..i'll look at it tonight. Also i'm not sure if they are supposet to be flat or vertical!
Steve
Everyone I've installed or seen installed has been flat. Too much wood cut out of the rafter decreases it's strength.
I left most of the meat in my rafters (only took 1.5" when I hogged out for the purlins, but if I was doing it again I might take more from the rafter and leave more in the purlin. My thought on this is that you can support an end gable with a post or two or a window buck or something pretty easily and of course end rafters only get half the load.
I've done many flat ways ladders, it works in light snow country, if the load or if wind load is heavy or as the overhang increases they need to go up on edge. As the overhang increases you should think about cantilevering the blocking inboard further (2/3 of the ladder blocking inboard, 1/3 hanging out) and doubling up the rafter you tie the blocks to inside. You can check the ladder lumber in flat ways or edgewise bending for the span of the cantilever.
We placed 4 ft gable end overhangs on our timberframe. We used 4x6 timber roof brackets and they look great. You can place 2x6 rafters on them. They lined up with the fake rafter tails we applied to the eaves.
Thanks guys for all the responses, i think i will be framing it like Jim_rogers post.