CM Toolkit Search

Grade Marked Lumber

Question: 

When webs are cut is it alright that sometimes the grade mark is removed? From a liability standpoint, what is the rule with grade marks and web members?

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?

Lumber Grades In Truss Design

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?

Lumber Concerns In High Temperature Low Humidity Climates

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?

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?

Allowable Mold Levels For Indoor Air Quality

Question: 

Some questions have been raised regarding the levels of mold in the lumber used in one of our truss projects. The issue of indoor air quality is up and coming. Do you have any information regarding standard allowable values? And how can we test for these contaminants?

Visual Grading Criteria

Question: 

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

Lumber Species

Question: 

What type of wood is usually used for wood trusses? I live in Louisiana and I would guess pine, but I want to make sure.

Green Building Products

Question: 

I keep reading about “green” building materials. Is SBCA working on a program for fabricators to get green?

Health Hazards Of Mold On Lumber

Question: 

What are the health hazards of black fungus on Douglas-Fir lumber?

Age Restriction On Lumber In Trusses

Question: 

I would like to know if there is an age restriction on wood trusses. How long after production are they safe to use? The trusses in question are at least three to four months old. Are they still safe to use? They have not been covered the entire time and are showing signs of age.

Mold On Lumber

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.

Lumber Sizes And Properties

Question: 

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

Life Expectancy Of Wood

Question: 

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

Cottonwood Lumber In Truss Construction

Question: 

I am developing a sustainable community in southeast Iowa. We have an abundance of cottonwoods nearby. I plan to have them sawn into dimensional lumber on the site and dry it there as well. I would like to use this material for trusses. A truss plate manufacturer informed me that because he had no data for cottonwood, he was unable to design trusses using it. Can you offer any advice?

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?

Location Of The Metal Connector Plates

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.

Average Plate Values

Question: 

I am a structural engineer trying to locate average plate values such that I can recreate truss designs for a roof structure that is over two decades old. The plates are not marked with any type of identification, therefore I need to take a conservative approach in the design and determine worst case scenarios.