Lumber

Lumber Fatigue And Decay

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?

Visual Grading Criteria

Question: 

Where can I find a copy of the criteria used to visually grade lumber?

Finger Jointed Lumber

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?

Two Hour Assembly Ul Number

Question: 

We have a local builder wishing to use floor trusses with a 2-hour assembly. I have shown him the 2-hour design on pages 17-27 of the second edition of SBCA’s Metal Plate Connected Wood Truss Handbook. Is this assembly UL approved? If so, what is the design number?

Lumber Grades In Wood Trusses

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?

Trusses Exposed To The Elements

Question: 

We are having a house built and on a recent visit we brought along a friend who builds houses for a living. He noticed that the trusses were wet and a bit moldy. The wood seemed warped, brown, and had white splotches on it. We are worried that it would later make the roof uneven. How could we tell how long the trusses have been exposed to the elements? What options do we have from here? Do we request new trusses, or can these be repaired?

Moisture Content Equilibrium And Truss Movement

Question: 

How long does it take the moisture content to stabilize in a wood truss? I live in southern California. Also, how much deflection should be expected in a scissors truss over a partition wall?

Information On Truss Fire Issues

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.

Fire Rating For Sloped Roof Truss Assemblies

Question: 

A question has come up concerning sloped roof trusses and fire assembly ratings. Some are reluctant to rely on test results from flat (parallel chord) trusses applied to sloped roof trusses. Do you have any information regarding the suitability of the fire rated ceiling assemblies for sloped roof trusses? Does the “minimum depth” requirement of the parallel chord assembly apply to the minimum depth of a sloped roof truss (i.e., heel height?)

Sprinklers Above Gypboard Ceiling

Question: 

I have a 29 x 72 mobile office with a 2-foot deep wooden truss above the ceiling that a client is required to sprinkler. Is there any way to avoid sprinklering above the gypboard ceiling?