Quality Control

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?

Shimming Or Shaving Variances In Truss Dimensions

Question: 

If you have the condition where you are out by the max tolerances of 1/2 in., how do you correct the situation? Do you shim the truss from the bottom? Shim from the top? I will assume you do not shave the truss off. What is the published corrective action for situations that cannot handle the variation in truss height?

Lumber Substitution

Question: 

If the truss design drawing specifies using 2x4 1650F SPF, can 2x4 No. 2 southern pine be used instead? What are some things that need to be checked?

Use Of Metal Plate Connected Wood Trusses In IBC Jurisdictions

Question: 

IBC 2012/2015 2303.4.6 and IBC 2012/2015 2303.4.7 state: 
2303.4.6 TPI 1 specifications. In addition to Sections 2303.4.1 through 2303.4.5, the design, manufacture and quality assurance of metal-plate-connected wood trusses shall be in accordance with TPI 1. Job-site inspections shall be in compliance with Section 110.4, as applicable.

Manufacturing Tolerances

Question: 

I am a structural engineer on a project with a wood trussed roof. I have noticed some variations in the peak height in a run of identical trusses. Do you have any information on tolerances for the final dimensions of manufactured trusses?

Owner Assurance

Question: 

As the owner for a building designed to have metal plate wood trusses, what documentation should I receive to be assured that the manufactured wood trusses delivered to the site have indeed been manufactured at a licensed and registered wood truss manufacturer under the required written quality control procedures?

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?

Preemptive Design

Can designing with lateral resistance in mind improve production QC?

A Training Transformation

To save you time and money, SBCA’s Wood Truss QC Program staff are going from on-site to on-call.

Do You Know What It Takes to Pick the Perfect Plate?

A lot of engineering goes into the design of metal plate connected wood trusses, including the connector plates themselves.