Construction

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?

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?

Fire Damage Assessment

Question: 

How do you evaluate whether a metal plate connected truss is still usable after exposure to fire? Are there any recommended tests?

Jobsite Inspections

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?

Installation Guidelines

Question: 

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

Temporary Bracing Documents

Question: 

Is it common practice for the supplier/distributor of a truss to provide a publication regarding temporary bracing with the delivery of the material?

Multi Ply Girders

Question: 

Girders are trusses specially designed to carry extra loads that are a result of the structural framing members they support. Sometimes a single ply girder truss is insufficient to carry the entire load, so the truss designer designs a multiple-ply girder. This is where identical trusses are built and fastened together to act as one unit to support the load. ANSI/TPI 1 states that girder trusses up to three plies thick can be fastened together with nails. Girders over three plies must be pre-drilled and bolted rather than nailed.

Create A Ceiling Vault In Existing Rafter Roof

Question: 

Is it possible to retrofit a standard rafter/joist style roof to a scissors truss configuration without replacing the existing construction?

Metal Connector Plates In Fires

Question: 

I am thinking of using wood trusses for the roofing/ceiling structural systems on some houses I shall build. I remember, though, an engineer/volunteer fireman commenting back in 1989 that the connector plates are prone to expand and pop off, early on in a fire, causing catastrophic structural failure. Was this the case, and if so, has this problem been corrected?

One Hour Roof Ceiling Assembly

Question: 

I am looking for a 1-hour roof/ceiling assembly for wood truss construction. I would like to apply the drywall directly to the bottom of the truss and also have insulation for sound control. Is this possible without using channels and what UL number would I use?