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I am building shed rafters from a plan I got off line. The spread is 12ft with rectangle shape and a king post in the center. Not sure of the roof pitch, but the king post is 2ft 8". Someone suggested I put some web supports or struts on sides of king post to the principal rafter for extra brace, since we have snow around 40 psf. The span of principal rafters is about 78" on each side from top to support tie beam at bottom and 12ft across bottom. I am using 1/2 plywood gussets at all joins, on both sides of truss, using 2" 6d common galv nails every 4" and glued Do you think I really need to worry about adding extra support? Thanks Dean

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    Do the plans tell you what their design parameters are for spf?
    – longneck
    Commented Jul 27, 2022 at 18:58
  • There's plenty of garbage designs on the internet. If there's no clear evidence of goodness just use them for inspiration.
    – Jasen
    Commented Jul 27, 2022 at 23:44
  • Longneck, no spec on spf.
    – Dean
    Commented Jul 28, 2022 at 1:11
  • Jasen, I agree. I will be adding them just for good measure and hopefully some piece of mind
    – Dean
    Commented Jul 28, 2022 at 1:12

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Look for plans to make a W style truss. Much much better than the oldfangled design that you picture in your question. The W style uses a bit more material for the struts but will support the upper rafter in its center zone dramatically increasing the stability and rigidity. The lower chord also gets supported as three segments instead of two.

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    The kingpost literally adds nothing structurally. A W adds considerable strength (for the same top and bottom chords) or permits use of less lumber if actually designed.
    – Ecnerwal
    Commented Jul 27, 2022 at 20:23
  • Ecnerwal, the king post adds some Stability in strength. Well it may not be much it does add.
    – Dean
    Commented Jul 28, 2022 at 0:52
  • Michael Kara’s, I have Already committed to using this truss design and made a jig to build them with. So I think I’ll just add a web piece on the sides of the king post. Any suggestions on what angle I should go? Thank you
    – Dean
    Commented Jul 28, 2022 at 1:06
  • The vernacular "kingpost with struts" goes 45 degrees from the kingpost for the struts.
    – Ecnerwal
    Commented Jul 28, 2022 at 2:15
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    @Dean - Well sorry that you committed to the oldfangled type design. Maybe you should reconsider and modify the jig for a W design more like this one (first picture) fixr.com/resources/all-about-roof-trusses. You main rafter pieces and lower chord can stay the same. Just the struts need to be modified to get superior result.
    – Michael Karas ♦
    Commented Jul 28, 2022 at 3:48

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