Roof Trusses

Question: 

I market 2x4 and 2x6 structural finger-jointed lumber. As of now, we have strictly sold it as a #2 product. However, we ran some through a bender at a sawmill to test the modulus of elasticity and it looks promising. The equipment showed no recognition of the joint; it acted like regular lumber. We would like to go forward with this venture in the hopes of offering an alternative MSR to solid lumber that may also be more cost effective. What do you need to have from us to get your approval?

Question: 

If you use hurricane clips to secure roof trusses from uplift, are you allowed to use fewer than the typical three nails in the bearing heel of the roof truss? I am concerned because we want to do the right fastening schedule, but three nails in addition to the hurricane clip splits the wood. What is the standard recommendation?

Question: 

I am building a new shop that is 30 ft. x 32 ft. I need to free-span the 30 ft. dimension. Where can I get a load chart that recommends lumber size and strategic locations of the angle braces to support the free span? I am going to field erect the trusses and stick build them on the building.

Question: 

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.

Question: 

We are building churches in Europe. These are modified pole barns and we are trying to use local materials and local volunteer labor. Since the truss is the heart of the building, I am looking for a method to test some completed trusses before the building is started to make sure they are strong enough.

Question: 

I have been told that the high temperatures and low humidity present in attics can cause deterioration of wood, leading to truss failure. Is this true? If so, what length of time are we looking at and can we see the deterioration in the wood by visual inspection?

Question: 

I am looking for some information regarding black surface mold on lumber. Does it alter the integrity of the lumber stress values? I have a client who wants to use “all dry” lumber for his construction but I do not know if this is really necessary.

Question: 

The industry suggests notching the gable end truss to support the overhang. Is this wise? What about a structural gable, or a gable designed with drag loads, or one with only partial bearing? How safe is it for a framer working with a truss that has the top chord cut repeatedly?

Question: 

How do trussed roofs perform in long-term service? Are there any reports of rusting in the nail plates, rot/insect attack, do-it-yourself modifications, or condensation and ventilation problems in the attic?

Question: 

How do I go about estimating the weight of a roof truss framing system? Is there a table of span vs. pitch vs. weight of trusses? Is there a guide available that shows how the components of various roof styles (hip, gable, etc.) are commonly framed and the associated terminology?