MSR Lumber | SBC Magazine

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?)

Post Fire Retardant Treatment

Question:

Is a Class A fire rating (provided by our liquid spray-on fire retardant) acceptable in certain situations?

Charring Of Trusses

Question:

Our home caught fire last month and burned partly through a tongue and groove ceiling to the trusses. Some are charred. Our contractor did a moisture meter test. An engineer for the insurance company said the trusses were only smoke damaged & the moisture meter test is invalid (it can be set to read anything). I found one article on charred trusses, but it’s pretty vague. We do not feel safe with the insurance engineer’s assessment because some of the trusses are obviously charred. We hired an engineer who agreed with us.

Fire Rating For Truss Assemblies Built With 2x3 Lumber

Question:

Are there any published studies or guidelines on the fire rating of floor trusses built with 2x3 lumber?

Information On Frt Roof Trusses

Question:

I need to obtain some information on fire-retardant-treated roof trusses.

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?

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.

Lumber Sizes And Properties

Question:

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

Substituting Fire Rated Wood Truss Assemblies For Light Gauge Steel

Question:

We recently received bids on a school project, which referenced UL P523. This assembly used light-gauge steel trusses. We noted on the drawing that we could accept an alternate design using wood trusses in lieu of light-gauge steel framing, if the alternate design could meet the fire ratings.

Duct And Light Penetrations Of Fire Rated Assemblies

Question:

In a small scale multi-family residential project, I'd like to use a wood truss floor-ceiling assembly to achieve a one hour separation between units. I'd like to directly attach the drywall to the underside of the trusses & use the truss space for ducts & lighting (the floor above will be lightweight concrete on plywood sub-floor). UL assemblies do not seem to address the duct/light penetrations in such an assembly. Can I achieve a one-hour rating in such an assembly and how are penetrations addressed? Can the ducts in the truss space serve both units above and below?

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