Construction

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?

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?

Gable End Bracing

Question: 

Some building designers believe that gable end webs need to be L-braced to 90% of the web length, which sounds fine. However, they spec that scissors gable end webs need to be braced to 100% of the web length. That means that in the field they are notching the braces to fit around top and bottom chords – you can imagine how difficult that can be. Is that necessary or even the intent of the web L-bracing?

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?

Sprinkler Loading

Question: 

Does the NFPA sprinkler standard address sprinkler loading? If so, how and where do I buy it? What other information do you have on sprinkler loading? How do other truss companies price jobs for sprinkler loading the plans do not include a sprinkler layout or even say what size/type of sprinkler system will be used?

Adequate Trusses

Question: 

Where can I find specs for what would be adequate trusses? I have a room with a 24 ft. span and my contractor is using trusses where the bottom plate is composed of 2x4s butted together and fastened with a metal plate. Is this ok?

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.