Market Education

Best Practices Provide a Best-Case Scenario

SBCA’s library of technical design and installation best practices has been expanded over the past year to help CMs navigate a wide array of code-related challenges in their markets.

The Right Tools in the Toolbox

Sometimes it’s hard to start a conversation. You know what you want to say, you think you know how the person you’re talking to will react, and yet finding the words to get the ball rolling and respond to the questions you know you’ll get is tough.

Truss Design

Question: 

Recently, I was invited to view a newly-constructed 60 ft. by 36 ft. barn, with homemade big timber trusses as follows: 36 ft. span, 12/9 pitch, construction was 26 ft. 2x12 rafters, bracing 2x6, ceiling joists were 36 ft. boxed, 6x12 out of overlapping (6 ft.), 2x12 glued and nailed center, 16 feet of joist doubled as an 8 ft. high loft, floor trusses were on 12 ft. centers atop posts deeply anchored with good footings, roof and wall cross ties were 2x6 on edge every 24 in., floor cross ties in the loft were 2x8 on edge every 16 in., 4 ft. snow load.

Adequate Trusses

Question: 

Where can I find specs for what would be adequate trusses? I have a room with a 24 ft. span and my contractor is using trusses where the bottom plate is composed of 2x4s butted together and fastened with a metal plate. Is this ok?

Size Of A Room In An Attic Truss

Question: 

Does SBCA have any guidelines regarding the size of a room in an attic truss? I have used a formula, length of room in inches divided by the depth of the bottom chord equaling less than 22. I was curious if any extensive studies or published articles giving more exact guidelines are available.

Installation Guidelines

Question: 

What are the requirements on the permanent bracing of bottom chords? Can gypsum board diaphragms be used?

Create A Ceiling Vault In Existing Rafter Roof

Question: 

Is it possible to retrofit a standard rafter/joist style roof to a scissors truss configuration without replacing the existing construction?

Partition Separation Lag Bolting

Question: 

Is lag bolting the bottom chord of a truss to the top plate of a wall a proper fix to correct truss arching, assuming the attic is properly vented?

Purlin Design

Question: 

Do you have information on purlin grades and species to meet 50 psf top chord live load using 2x4s on edge 24 in. O.C. over trusses at 6 ft. O.C.?

Determining Necessary Truss Height

Question: 

How high would a truss have to be to span 33 feet 9 inches?