Roof Trusses

Spacing Requirements On Sheathing

Question: 

I am looking for help on the spacing required to screw down a BHP B-36 20 gage roof deck to wooden trusses spaced at 5 ft. 4 in. O.C. and 24 in. O.C. Do you know of any published codes or specifications on the above?

Cutting Trusses

Question: 

Our home has 2x4 roof trusses spanning 25 ft. spaced 16 in. O.C. Currently, there is limited attic storage on a plywood subfloor on the bottom chords, accessed via a small hatch in a closet. We would like to install a fold-down attic stair with a rough opening size of 25.5 in. x 54 in., with the long dimension perpendicular to the trusses. This would mean cutting the bottom chords of three trusses to frame the opening. Is this possible?

Floor Trusses With Masonry Bearing Walls

Question: 

We would like to know if there is a problem with using wood floor trusses with masonry bearing walls without a ledger. Our local supplier has told me that encasing the wood truss in the masonry wall could be detrimental to the truss due to moisture. What, if any, suggestions do you have for this condition? If a bottom chord bearing is used, do the trusses need fire cuts? The two-story building contains masonry bearing walls with wood trusses on the second floor and wood trusses at the roof.

Post Fire Retardant Treatment

Question: 

Is a Class A fire rating (provided by our liquid spray-on fire retardant) acceptable in certain situations?

Wood Three Hour Fire Assembly

Question: 

Is it possible to construct an assembly for ceiling between first and second floors using 2x with few layers of gypsum to obtain a 3-hour fire rating?

Substituting Fire Rated Wood Truss Assemblies For Light Gauge Steel

Question: 

We recently received bids on a school project, which referenced UL P523. This assembly used light-gauge steel trusses. We noted on the drawing that we could accept an alternate design using wood trusses in lieu of light-gauge steel framing, if the alternate design could meet the fire ratings.

Damaged Trusses

Question: 

I have just moved into a new home and during the construction I noticed that one of the trusses in the garage was damaged. The web plate had come off in two different locations. I notified the builder and they said they would take care of it. Approximately two weeks after I moved in, I noticed the ceiling in the garage started to sag, so I went into the space above the garage and found the truss was never repaired. I again notified the builder and they sent someone to fix it. I went and looked at the fix and this is where my question comes in.

Finger Jointed Material

Question: 

Is finger-jointed material allowed in the manufacturing of trusses?

Penetration Of Fire Walls

Question: 

Can a roof truss penetrate a one-hr. tenant separation wall without having a one-hr. rated ceiling? The building official insists that the 2x4 chords are combustible and nullify the integrity of the one-hr. rated partition that is constructed in an attic above an 8 in. C.M.U. bearing wall. The partition consists of gypsum board attached to 2 x 4 stud framing. The building official insists that a ledger must be attached through the gypsum board to support the trusses each side of the wall. This is almost saying that any rated assembly must have bearing only on other rated assemblies.

Wood Framing

Question: 

I am conducting an investigation on the costs associated with building a 15,000 sq. ft. addition to an existing school building. I need to determine if wood trusses, steel bar joists or light gauge steel trusses would be the most economical material for the building system. The truss spans range from 42 ft. to 56 ft.