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Installing Rafters On Earthbag Building  RSS feed

 
Posts: 2
Location: Montana, USA
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Hi there everyone, my name's Jared and here's my first post. Sorry if I should have done an intro post elsewhere as forum etiquette, but I'm short on time and looking for some quick help.

I'm about to start building an EB shed for my mom, and need to hurry and submit plans to the local building code guy (who has already given approval to the general idea of EB).

The building will be, if all goes as planned, 13' 4" wide. We are going to put on some common rafters I'll be making at 4/12 slope. I'm hoping to use 2x6 lumber for the rafters.

My question is, since the wall is going to be approx 15" wide, how do I cut the birdsmouth/seat cut wide enough for the wall without cutting too deep into the rafter? If I cut too deep the rafter will be weak, but if I cut a shallow 15" birdsmouth without maintaining proper angle with the plumb cut I highly doubt things will line up right.

Anybody run into a similar situation? Ideas on how to overcome this? Do you need more info I might have forgotten to mention?

Thanks!
 
Posts: 126
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Hi Jared, a little sketch would help a lot.

Don't worry about the introductions. We all tumble around like socks in a dryer here-you'll meet pretty much everyone eventually.

 
Michael Sohocki
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My immediate impression is that if 2 by 6 threatens to be weak after cutting in, they also come in 2 by 8. The cost will increase but it might avoid a redesign which would cost more time and headache.
 
Jared Binitial
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Location: Montana, USA
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Hey Michael, thanks for reaching out!

I don't have the best quick drawing skills, and am not sure exactly what you'd like to see in more detail, but here's the drawing from the book I'm using as my main reference showing methods of attaching the roof to the wall. They say even 2x4 lumber will work, but don't talk anything about slant and seat cuts. The picture seems to show some kind of very shallow cut, but I don't know anything about proper method to determine the angle and whether such a cut would be code compliant anywhere.

Anyways, see attached photo for what the book vaguely explains to do.

Rafter-on-Wall.jpg
[Thumbnail for Rafter-on-Wall.jpg]
 
Michael Sohocki
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ROPE!??

Whoah, dude.

That scares the shit out of me. In a hurricane with 100 mph winds, can you imagine being inside a structure held together with.....ROPE?

Don't build for the good days--build for the bad days. The last thing you want to think when you jerk on a roof beam is, "hmmm...ambiguous....."

If ever there was a time and place for 1/2" steel bolts (or even 5/8") with locknuts and washers on both sides, this woukd be it.

You want to anchor way down deep in the mass of a wall--say, six feet of steel pipe, or a large wooden beam, something with high tensile strength, anchored really really good beneath hundred and hundreds of pounds of something--then mount (at least the corners) to that.
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Posts: 206
Location: Europe
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Rope can be surprisingly strong and could quite possibly be stronger than a connection using nails or screws. The rope used for staw bales can take 200 - 400kg (440 - 880 pounds). As a loop has two sides it holds twice that.
So a few loops will easily exceed the strength of the beams.
 
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