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Can a Scissor Truss be Designed for a 28×40 House?

Asked by Terry on October 19, 2014

Can A scissor truss be designed an put on the roof of a new house 28 feet wide  x 40 feet long,,,

Scissor Truss

Scissor Truss

Scissor trusses used for catherdral ceiling affect over half of house approx.,,Re ,,,over living room,,Kitchen & dineing area,,,Approx exterior roof pitch 3.5/12 or 4/12,,Balance of trusses would be same pitch,,,but just normal gable trusses,,,I want to line the interior of the scissor of the  with pine or cedar lumber ?????,

White Pine

White Pine



I read somewhere ,,,wher scissor trusses flex with snow load,,but only one half inch,,,THKS,,,Terry from Northern Alberta Canada


Answered by Doug Friant

Hi Terry,

28′-0″ Scissor trusses are certainly possible, however a 4/12 pitch is really much too shallow. You need about an 8/12 pitch for them to work, with the bottom chord being about 4/12. King post or queen post trusses are a better choice for a low roof pitch.

King Post Truss

King Post Truss

Queen Post Truss

Queen Post Truss

The material would most likely be douglas fir. Cedar and pine are usually too weak.

Douglas Fir

Douglas Fir

Best regards,

Doug Friant

  1. Vern Brundle says:

    I have a park model trailer. 14 x 60 plus on side 13 x 25. I would like to have roof with truss 28 x 72 . What is the cost per truss. best to get hold of me by email. Vern

    • Hi Vern, our engineer will need more info in order to evaluate the size of the timbers to create the trusses you’ll need, then we can figure out the pricing. Please send an email to [email protected] and depending on your location, Sue or Mike will get you started. Thank you for your question and we look forward to talking with you soon, Sandy

  2. Viclif Thomas says:

    Which Truss is best to get MAXIMUM ROOM AREA/HEIGHT inside a Church? Thanks

  3. April Cook says:

    I like the look of queen post trusses. I would love to have those exposed in my home. I also like your tip to use douglas fir for it’s strength. I’ll remember this for when we are building our home.

  4. John Wagner says:

    I am looking a having a 26′ x 52′ lodge/shelter built. It will have a 18 to 20 foot porch exstension added. Your ” fresh air cabins” design kind of matches my Ideas. The building will be clad with 2 1/2″ x 9″ cedar log looking siding.

    I would prefer to use No. 1/Structural select Douglas Fir for walls and roof. Decking will be yellow cedar.

    I would prefer the to have a scissor truss. With a minimum of a 8/12 or 12/12 pitch on roof. The structure must pass California earthquake code.

    Crazy Idea. or is its possible?

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