Joints in Roof Rafters and Studs?

[ken_rychlik]

If you build it truss style for the roof framing, you could use shorter pieces. There would be webbing that would intersect the joint, giving the compression load requirement. At these joints, most buliders use the mending plates to tie them together, but plywood has worked for years also.

[archis]

Ken,

Great idea, thanks!

Here's a site for the plywood designs:

http://www.physicaldesignco.com/

[ken_rychlik]

One more thing to keep in mind. Building codes allow for finger jointed studs on interior walls only in Texas. They are not allowed for an outer wall. You local codes may vary, but is something you should check out.

[michael_schwartz]

I would do a bit of research into the field of timber framing if your interested in structural wood joinery. I would also take a look at Japanese examples as well as they use some really interesting joinery. On a smaller scale using a shopbot to cut such joinery might be an interesting possibility. However full scale joinery on an 8x8 or 10x10 timber would of course present a number of difficulties and that would be the time to get out a large circularsaw and chain mortiser.

If you had to build a structure with nothing more than what you could carry in to the woods, a look at historic methods may give you the answer your after. After all 200 years ago if you were going to set off to build a house in the woods, you were probably limited to what you could carry on a horse.

Of course the more economical/modern solution may be to work with an engineer to design structural brackets/connectors to meet your needs.

Hopefully codes aren't too big of an issue where your planning to build.

[kevin]

I'am in a remote area they don't care about looks .Just price .
I don't offer advise but you have to come up with a speciality item for which there is no competion
Or go door knocking offering cnc sevice

I live in a semi remote area .We have box stores 1 hr drive they have perfab sheds you name the size .Plus the'll ship to Labadour I hr flight
Mined you there is a huge boom in Labadour 1 billion dollar mine expansion funded by the China
Plus down the road from me there are two major project over a billon dollars each one now and next year

[bill.young]

Hey Jim,

I'm not much help with lumber though we have tested a few joinery methods without much success. The biggest problem was trying to hold construction lumber flat and straight to cut it...we just couldn't find anything locally that was consistently straight enough to cut accurately. The best we could find was Structural grade yellow pine, but that still required some picking and is only available here in wider boards that would have to be cut to width first for stud...it may be different where you are.

I have worked quite a bit on buildings using plywood, though. You've found the physicaldesignco site and I'm sure the MoMA house that we worked on with those guys. It was amazingly strong and went together quick and might be an option. The Shelter2.0 project also breaks down into small pieces that would be easy to carry, although the floor and wall panels are in the 3'x7' range which might be a haul if you had to carry them far.

Our newest projects have been laminated plywood versions of timberframe construction, with the joinery designed and cut into the layers of the pieces (Ted calls it "plyberframe construction" which has a nice ring to it!). There's a video on youTube of our first building http://www.youtube.com/watch?v=KtW0jzPHnD4, but since then we've developed a simple method for making the laminations sort of "self clamping" during glueup, so that the pieces could be cut offsite and easily glued into finished parts on the jobsite without a boatload of clamps. All the parts would be small enough to carry to the jobsite, to be glued up into big beams.

And don't miss Rob Bell's amazing geometric structures for inspiration...they are very cool.

http://www.flickr.com/photos/zomadic/

Bill

[navigator7]

Chuck,

I get the butt joint working well for studs where compression is along the length of the board. It seems to me that for a rafter where the load is closer to perpendicular to the length of the board, a finger type joint would me more sense.

I understand your conundrum. ;-)
You might want to look at something called a Flat Truss or a Vaulted Parallel Chord truss. It consists of many
2x4's finger jointed into one very strong truss assembly.
I am using a flat truss in my shop I have under construction for a second story floor. A 25' span with very significant floor loading ability.
No metal plates....just glued finger joints.



http://www.classictruss.com/roof_truss_facts.asp

These types of structures are normally engineered, cut , glued and fabricated at a plant. Engineering follows it all the way to permitting.

If you are a botter ....it changes the equation. The goal is to make many trips with lighter loads as conventional methods are out.
The question is, then, can you cut a suitable finger joints, package and ship the joints without too much damage, create a parallel and square fixture on site, glue and clamp and then lift the resultant structure into place?
Rain snow and cold, dust dirt and damage?

I'd come up with a design that suits you and then figure out a way to do a destructive test. Break it. As the Building Dept sounds like it will be out of the loop.....you are the beaver. (BTW...I like beavers. They have more sense than most building inspectors ;-)

[wberminio]

Way too cool Bill!

[navigator7]

Way too cool Bill!

Dittos!

No tool bags.
No compressor.
No power tools.

Did anybody wince when that guy stuck his fingers under the column?
Yowsser...lol.

Waterproof Resorcinol Glue, Bill?

[bill.young]

Thanks Erminio, though I can't take too much of the credit. All these projects were collaborations with others, most with my buddy Robert Bridges. Fortunately both of us are willing to try out ideas when they're still pretty half-baked, which sometimes yields some pretty neat results but also can make for a pretty big scrap pile!

Happy Holidays,
Bill