Engineering

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.

Bottom Chord Dead Load

Question: 

I have built a 30 ft. x 40 ft. pole barn with nine 30 ft. 2x4 7/12 pitch trusses that are 5 ft. O.C. I am planning to finish out the interior and will attach 7/16 x 4 x 8 OSB sheets to the trusses for my ceiling. Along with this, I will have to add several 2x4 nailers across the 30 ft. span between the trusses to attach the sheeting to. My question is: will these trusses have any problem supporting this ceiling? I am not planning on anything being placed in the section above the ceiling and there will be no walls or supports erected between the ceiling and the floor.

Wind Loads From Solar Panels

Question: 

I am looking for information on point loading trusses. We manufacture mounting structures for solar panels. Typically, 10 to 15 sq. ft. of solar panel is supported by one standoff. Under extreme conditions – 50 lbs. per sq. ft. of wind load - we can transfer 500 to 750 lbs. of force onto one point of one truss. Are there any standards on this issue?

Truss Deflection Onto Non Load Bearing Walls

Question: 

I am installing a 40-foot scissor truss that is designed to deflect about ½ inch. I am concerned that the deflection will cause an interior partition wall to pick up some load from the truss and transfer it to the floor system. Should I double up the I-joists under this partition to pick up the extra load?

Repairs To Field Modified Damaged Trusses

Question: 

As a home inspector, I have recently inspected an existing home with an attic truss system installed. Several of the truss web members have been cut away to allow access to an attic-mounted heating system. Can you recommend repairs to a truss with cut web members?

Structural Composite Lumber In Trusses

Question: 

The lumber used in most metal plate connected wood trusses is either visually- or mechanically-graded solid sawn dimensional lumber. However, the Truss Plate Institute's ANSI/TPI 1 allows the use of structural composite lumber (SCL) products such as laminated veneer lumber (LVL), laminated strand lumber (LSL) and parallel strand lumber (PSL). These engineered wood products can conceivably compete with sawn lumber and complement it in truss designs.

Sloping Floors

Question: 

In our one-year-old home, as you approach the hallway, the floor slopes downward. Our home inspector said that this was most likely due to the fact that the walls were resting on the floor as opposed to being load-bearing walls. What has been your experience with sloping floors in a new home? The floors are very flat elsewhere until the walls start. Do you think this sloping could turn into a structural problem eventually?

Determining The Load Capacity Of Trusses

Question: 

I am doing research for clients who have flat roof trusses to which they are adding a second story. We are now looking for information on the trusses to determine what their load capability is. What do you need to know to help us determine this?

Vent Sizes

Question: 

I have mono trusses on either side of a firewall. I have the fire rating/wall material between them. Can I place a ridge vent above these two? Or should I use vents? How do I calculate the appropriate vent sizes and styles?

Fire Cuts

Question: 

What type of construction uses a fire cut truss? Could you describe a fire cut truss?