Design

Can you explain drag loads and how to calculate a drag load pertaining to roof trusses?

We are currently developing a project which specifies “Seismic Design Category C.” We are an East Coast truss manufacturer and have not encountered seismic requirements before.

If trusses blew down from insufficient temporary bracing and the contractor put them back up without the knowledge of the truss manufacturer and gave the truss manufacturer a letter stating that the trusses were okay, is that sufficient? Do you know of any truss manufacturer who would accept this?

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

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?

I recall seeing a design recommendation several years ago regarding installation of hanger nails above the neutral axis of the bottom chord of a plated girder truss. The intent was to avoid dumping large loads into the bottom chord, below the neutral axis. Can you tell me where I can find this information?

I am looking for a set of guidelines or “rules” for members of the SBCA. Are truss plants really not allowed to speak of business matters? I think that is unfair. I'm not going to call up our competitor and tell them that they aren't charging enough and taking all the business. I just want all the truss plants in my area to get together and decide how we are going to do business. We need to standardize the industry.

We are planning to add 1/2 in. cement board and 3/8 in. quarry tile to a kitchen floor. We need to know if the floor trusses will handle the additional weight. The floor trusses are 19.2 in. O.C. and the loading numbers are 40-10-0-5. What do these numbers mean?

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?

When you’re selling trusses through a lumberyard and the contractor calls to say that the “trusses don't fit correctly,” who has the ultimate responsibility for the trusses? I argue that the lumberyard is responsible since we have provided them with all the information on how the job was designed, even though they may or may not have passed this information on to the contractor.