Truss Building

[hopro]

Have kind of a strange application where I wish to build my own trusses.

Have a flat roof and going to put a truss from about 3 foot height down to the height of a 2x4 over a span on 20 feet. Its really my only option on a two storey split level where the truss would start below a couple of windows. I really need to do this to once and for all to solve problems of a flat roof (buckles due to high florida heat). Am putting new shingles on the rest of the house and might as well do this at the same time so I don't have matching problems later.

The question: What type of 2x4 lumber should I use? #2 Kiln dried, southern yellow or something else? Looked in some books but can't quite find the answer.

Thanks

[Jack the Contractor]

First of all, you cannont build a truss. You can build a rafter, but not a truss. Trusses are made under very exacting conditions with giant presses, to exact Engineering specifications. However, they do build trusses for just exactly what you want to do. They are called a Half truss or Butt Truss. You simple take your measurements to your Lumber yard or Local Home Improvement store, and they will order your trusses built for you. The will be to exact specs and also the load limits for your area. They are very inexpensive, and will be cheaper then the lumber you would need to try to build them yourself. You will need a building permit for this. I doubt you could get a permit for hand built rafters unless a licensed contractor built them. I am doing two jobs right now just like yours with flat roofs. Mine are just bigger. I should say that I am assuming you want your roof to just slope one direction. If you want a ridge like a regular roof, just order regular trusses. Good Luck