Frequently Asked Technical Questions

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Frequently Asked Question

I need to obtain some information on fire-retardant-treated roof trusses.

Frequently Asked Question

I am trying to develop a guideline for my firefighters regarding initial fire attack in buildings with light-weight trusses. My concern is truss failure, especially when exposed to fire. Is there any information on failure time related to flame impingement? Any information about truss failure – especially in a fire condition would be helpful.

Frequently Asked Question

Are there any associations that have recommendations for the installation of wood trusses?

Frequently Asked Question

What are the requirements on the permanent bracing of bottom chords? Can gypsum board diaphragms be used?

Frequently Asked Question

What are the requirements for installing “valley set” overlay roof trusses? I am interested in nailing and support conditions. Some engineers ask for the bottom chord of the valley truss to be ripped to match the roof pitch of the underlying trusses. Is this necessary?

Frequently Asked Question

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?

Frequently Asked Question

Consider this statement from a set of construction contract documents: “The Truss Manufacturer is responsible for inspecting the truss installation, bracing, anchorage and bearings and preparing a letter of verification stating that trusses are installed and braced properly.” At first glance, it may seem that the truss manufacturer is the most logical party to perform such an inspection. They are the truss experts, are they not?

Frequently Asked Question

We have been specifying laminated veneer lumber (LVL) beams for some time now. The plans usually state, “Beam to be engineered and supplied by truss manufacturer.” What kind of liability issues do I need to watch out for?

Frequently Asked Question

What is the life expectancy of wood that was used in an attic truss? Does fire retardant change the life expectancy?

Frequently Asked Question

I am planning a 36 ft. x 60 ft. clear-span horse barn with posts set 12 ft. O.C. If I use 2x6 verses 2x4 wood trusses what would the proper spacing be? The roofing is 29 ga. K-panels metal with insulation, and winter snowfall is minimal in our area.

Frequently Asked Question

I am looking for a company that can properly transport wood roof trusses on a one-time basis that are too large to fit into a box trailer. Trusses are to be fabricated in NC. Do you have any recommendations? Could be a specialty hauler or another truss fabricator in the area that has the special frame truss hauling trucks.

Frequently Asked Question

I am building a home and want to use floor trusses. How can I find a local manufacturer?

Frequently Asked Question

I was working on a job that had trusses that span more than 78 ft. with a 9/12 pitch. We had the #5 truss being installed when the #4 truss gave way. The trusses that were being installed are a two part system. The bottom set is what you would call hip trusses. The trusses contained 2x6 bottom chords, 2x8 top chords and rafters, and 2x4 webs. The roof sheathing was to be 3/4 in. plywood, 15 lb. felt paper and roof shingles. The ceiling was to be 5/8 in. drywall. The #4 truss sheared about 1 in. off the wall.

Frequently Asked Question

Has there been any research or studies on long-term deflection of metal plate connected wood trusses? How much deflection is allowed?

Frequently Asked 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?

Frequently Asked 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?

Frequently Asked Question

What is fatigue in lumber and how does long-term fatigue affect lumber? Does long-term fatigue cause cracks in lumber? What is the difference between long-term fatigue and decay? How do you determine whether lumber has been subject to long-term fatigue or decay?

Frequently Asked Question

In truss manufacturing, can hemlock, fir and spruce be used instead of Douglas Fir/Larch? What grades can be used: Structural Light Framing (Select Structural through #3) only, or Light Framing (Construction through Utility) as well?

Frequently Asked Question

The grading rules usually permit some percentage of visually graded lumber to be below grade – I believe it is 5%. ANSI/TPI 1 requires that all lumber used in trusses be of the grade specified by the truss design. A strict interpretation of ANSI/TPI 1 would require that the fabricator cull the 5% that is off grade. What are your thoughts on this?

Frequently Asked Question

Where can I find tolerances and measurements of green and dry lumber?