Timberframe Rafters/Truss

[Jeff]

I'm thinking about putting up a small building this year behind my polebarn as a shop. (yes, my polebarn is too small already!) Is it possible to make trusses out of 6 by 6 white cedar that is 8ft long that I have on hand to span 12ft?   I'd like the building to be 12 by 26' or so.

[Don P]

Yes... but any chance you can get some 12' material for the bottom chord, it would be easier to build.
How are your local building officials with home grown wood?

[carhartted]

Using a hammer beam would use shorter wood since the bottom span is broken up.

Depending on the roof pitch a scissor truss may work. They generally span ⅓ from the top to ⅓ from the bottom of the top chord.

[Jeff]

I was thinking a pitch with some head room. 8ft side walls. I want to see the beams on the inside.
I'm not asking permission. I'm going to just build it. I was hoping to avoid collar ties.

[Don P]

The scissor truss would work, somewhat tricky to build. Rafters with a tie across their feet to make a triangle is another way.

What it sounds like you are describing is a ridgebeam with 6x6 rafters hanging down from it. If the rafters are hanging they don't need rafter ties to keep their feet from spreading. 26' is too far for a ridge beam but if you can tolerate a central post at each end and in the middle under a ridgebeam then the span is down to 13' for each of 2 spans. The ridgebeam would probably need to roughly be in the range of 6x12 depending on species and grade. Post spacing on the perimeter would factor into the eave beam sizes. Is that along the lines of your thinking?