Suggestions for framing the gable overhang.

[mmhailey]

I am in the process of enclosing my frame, and I have been working on the gable end today.









I would like to frame in an overhang on this end of the cabin. I am planning on 6/4 T&G hemlock, then 4 inches of foam, and strapping, then a metal roof. I was thinking of using a ladder attached with timberlok screws, something like this:

Here is a sketchup of what I was thinking of doing.





I would prefer to limit how far back onto the roof I attach the ladder, since I'll be giving up some insulation, and thermal bridging.  I suppose using 4 inches of the 8X8 rafter, then the 4 3/4 of the curtain wall, should allow me a considerable cantilever, but I just don't know how much.

Also are there some good techniques for limiting uplift? I get big winds here. :-[

[Rooster]

MM,

Instead of making a ladder for the overhang, you might be able to use the strapping for the roof steel as the overhang.  Pole-barn purlins extend past the end rafters to create overhangs.  As long as your rim board is nailed to your stud wall assembly, then your strapping can be directly nailed or screwed to the rim board.  This system has less bridging.  I hope this helps.

Rooster

[frwinks]

looking good MM Glad to see you chose the modified REMOTE wall assembly on your frame.  Looks like you making great progress 8)

I used the same detail as what Rooster is suggesting and that is to use the strapping layer to build out your eaves and gables.  All my strapping is 16"OC and is incredibly strong at the overhangs.  You could tie the overhang back to the framing via a soffit box if you're planning a 3'+ overhang.  I didn't think mine needed it for the 2' overhang and our Peng agreed.  This detail also eliminates ALL thermal bridging as you can see in the below pic.  Apart from door/window frames there is a continuous layer of insulation around the entire frame.


For uplift, I used 12" and 14" panel screws to secure both layers of stapping around the perimeter of the house straight into the timber rafters.  Again a very solid detail and with only 4" of foam on yours, you might be able to get long enough screws from your local building center. 

[mmhailey]

 ;D Head slap to forehead!!!  ;D   I can't believe I didn't think of that.... Much simpler than my idea, and just another reason I love this forum.  I have some 1X4 hemlock strapping, I have stickered, that I was planning on using for the walls, and roof. I think what I will do, is use it for the walls, and on the roof vertical strapping, then 2X4s for the horizontal.

Both of your plans also keep the 6/4 hemlock T&G from extending out into the weather. Even though they would be under the overhang.

I would like to use red cedar for the soffit. I also plan on making some false rafter tails, and attaching those under the eaves. I want to dress those with an Adze. I read somewhere those are called jet blocks, but don't quote me on that.

Also I am getting my Timberlok screws from a place I found on Ebay. Somewhere between .50 and .65/screw with free shipping, which is a huge deal for me. I think you can see in the pics I posted the screws at each stud into the girt.

[frwinks]

Both of your plans also keep the 6/4 hemlock T&G from extending out into the weather. Even though they would be under the overhang.

There's just no way of sealing up the joints between the boards, t&g or not.  I tried it on one  end, using acoustical sealant to seal up the joints between boards..what a mess   ended up sawzalling all the boards flush with the gable rafters and running the wall foam right up the the top of roof foam as I did with the rest of the house.  Much tighter detail and 0 thermal bridging.  I will continue with some lighter (.5") boards under the overhangs instead.

[ballen]

frwinks,
That looks great for the eves.  What about the gable? I need about 3 feet of overhang on the gable end.  Just do what Rooster shows?
I was thinking of an external plate, tie, rafter and brace but don't know how to connect it all to the side of the building without causing a thermal connection.
Thanks,
Bill

[frwinks]

yes, the less beams/bolts/pipes/etc compromising the thermal envelope the better IMO.
The horizontal layer of the strapping in my detail builds out the gables, just like in Rooster's pic.  My overhang, from the last attachment point, is 25" and solid with a 1x7 cedar fascia board tying the tails together.  3'-4' might be pushing the limits of 2x material on flat and a conventional ladder box, like in MM's pic, might be a better option in this case.
How do the strawbale guys detail their roof/wall connections?  From what I read, it's not uncommon to see 5' overhangs on straw homes...

[mmhailey]

Here is a sketchup, of my planned overhang.





I will use full rough cut 1X4 on 16" centers as my vertical strapping, as I have a lot of that on hand. I then will use 2X4s on 24" centers for horizontal strapping. Right now I am contemplating going over this with 1/2" plywood and 15#felt, before I put on the metal. I have a call in to the metal manufacturer right now, but I am pretty sure for the wind resistance he is going to say I need a solid substrate.

You can see the 1X4 gives me the eave overhang, where I will add Soffit boxes, and some false rafter tails. The gable overhang is supported by the 2X4s on the flat. This layout lets me completely enclose in foam, with very little thermal bridging.

That is the plan now.  If it changes I'll post it here.

[ljmathias]

My metal supplier strongly recommended not putting the roofing directly on solid decking, instead using horizontal 1X4's (untreated, emphatically required, not treated).  If you nail to roof trusses with galvanized ring shank, they will hold great, then put your metal on with the screws located where they should be according to the metal manufacturer.  All in all, very resistant to wind- metal roofs out lasted shingles by about 4 to 1 (ok, so I made the number up, but it was a high) here in the south when Katrina went through.

Anyway, good luck.

Lj

[ballen]

I just came across this pic in another topic.  If one wants to do a gable overhang as large as the one in the pic below, do you think the horizontal strapping with a timber support at the end like in the pic would work?  I am curious if the timber support at the end of the overhang needs to tie into the house in anyway or is it "free standing" with the connection to the strapping/roof the only tie-in?