Frequently Asked Technical Questions
In a hip roof application where jack trusses connect to a girder truss using pressure blocking (power blocking), what is the proper installation and the span that is acceptable before a hanger is required?
How much OSB can be stacked on a floor deck without damaging the trusses?
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. The trusses came with data sheets that have a great deal of information but none of it directly answers my question. It does state that the truss ID is R01 and the loading is 20-4-10 60.00 in. O.C.
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?
Can I put a wood deck (1/2 in. plywood) on top of the bottom chord of a 26 foot span truss 24 inches on center?
I am a structural engineer designing pool cage structures that are typically attached to the house at the fascia board. Sometimes, the structure is attached where trusses are behind the fascia board and other times there is a framed gable end overhang. Do you know of any information concerning this additional load on the trusses or overhang under design wind loads? Is there a limiting distance on the amount of overhang? I know trusses are designed for certain uplift and the pool cage will add to this uplift at design load, but what about the gable end overhangs? Are there any calculations regarding the amount of uplift they can take?
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?
I am a building inspector and I have a question on information provided on truss design drawings. What does the uplift reaction number represent? Some manufacturers are very specific and state “to provide for mechanical connection of the truss to the top plate with a connector capable of withstanding a specific load.” Others simply list the uplift reaction with no further information. These are the ones that have caused a debate as to what the number actually represents. Some say the uplift is a net number to size a connector to, and others say it is a gross number that can be reduced and a lower rated truss connector used. Unless the engineer can provide calculations and be willing to “stamp” the calculations, we have stood by the uplift load listed, as the load to size the connector to.