jar546
Forum Coordinator
In the 2018 IRC, Section R802.10.2 speaks to the bracing of roof trusses. According to this section, when using bracing for roof trusses spanning 60 feet or greater, at what intervals should the bracing be applied?
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Roof Bracing for Spans Greater than 60'
- Thread starter jar546
- Start date
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- irc roof truss truss bracing
Inspector Gadget
Registered User
Aren't trusses engineered elements? Y'all do what the engineer says?
2018 IRC
R802.10.2 Design
Wood trusses shall be designed in accordance with accepted engineering practice. The design and manufacture of metal-plate-connected wood trusses shall comply with ANSI/TPI 1. The truss design drawings shall be prepared by a registered professional where required by the statutes of the jurisdiction in which the project is to be constructed in accordance with Section R106.1.R802.10.2.1 Applicability Limits
The provisions of this section shall control the design of truss roof framing where snow controls for buildings that are not greater than 60 feet (18 288 mm) in length perpendicular to the joist, rafter or truss span, not greater than 36 feet (10 973 mm) in width parallel to the joist, rafter or truss span, not more than three stories above grade plane in height, and have roof slopes not smaller than 3:12 (25-percent slope) or greater than 12:12 (100-percent slope). Truss roof framing constructed in accordance with the provisions of this section shall be limited to sites subjected to a maximum design wind speed of 140 miles per hour (63 m/s), Exposure B or C, and a maximum ground snow load of 70 psf (3352 Pa). For consistent loading of all truss types, roof snow load is to be computed as: 0.7 pg.
R802.10.3 Bracing
Trusses shall be braced to prevent rotation and provide lateral stability in accordance with the requirements specified in the construction documents for the building and on the individual truss design drawings. In the absence of specific bracing requirements, trusses shall be braced in accordance with accepted industry practice such as the SBCA Building Component Safety Information (BCSI) Guide to Good Practice for Handling, Installing & Bracing of Metal Plate Connected Wood Trusses.Beyond the scope of the IRC, must follow an engineering design.
mtlogcabin
SAWHORSE
I would call for a special inspector.
R109.1.5 Other inspections.
In addition to inspections in Sections R109.1.1 through R109.1.4, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.
1705.5.2 Metal-plate-connected wood trusses.
Special inspections of wood trusses with overall heights of 60 inches (1524 mm) or greater shall be performed to verify that the installation of the permanent individual truss member restraint/bracing has been installed in accordance with the approved truss submittal package. For wood trusses with a clear span of 60 feet (18 288 mm) or greater, the special inspector shall verify during construction that the temporary installation restraint/bracing is installed in accordance with the approved truss submittal package.
R109.1.5 Other inspections.
In addition to inspections in Sections R109.1.1 through R109.1.4, the building official shall have the authority to make or require any other inspections to ascertain compliance with this code and other laws enforced by the building official.
1705.5.2 Metal-plate-connected wood trusses.
Special inspections of wood trusses with overall heights of 60 inches (1524 mm) or greater shall be performed to verify that the installation of the permanent individual truss member restraint/bracing has been installed in accordance with the approved truss submittal package. For wood trusses with a clear span of 60 feet (18 288 mm) or greater, the special inspector shall verify during construction that the temporary installation restraint/bracing is installed in accordance with the approved truss submittal package.
Didn't believe it changes the intent of my response. I did after all post the whole code section and quote from it.
wwhitney
Registered User
This article agrees with that interpretation (although it says the limits only apply when snow load controls the truss design; when other loads control the truss design, it suggests the IRC still applies.)
STRUCTURE magazine | Code Requirements for Residential Roof Trusses
www.structuremag.org
Yet the language "The provisions of this section shall control . . . where . . ." isn't quite the same as saying "The allowances of this section shall only apply where . . ."
Cheers, Wayne
jar546
Forum Coordinator
According to Section R802.10.1 of the 2018 IRC, "Trusses shall be designed in accordance with approved engineering practice. The design of permanent bracing shall be included in the truss design drawings. Permanent individual truss member restraint/bracing shall be designed by a registered design professional.
steveray
SAWHORSE
And at 60' I think even the temp bracing gets engineered...IIRC
Yes, but the truss engineer cannot simply rely upon the SBCA Building Component Safety Information (BCSI) Guide to Good Practice for Handling, Installing & Bracing of Metal Plate Connected Wood Trusses where exceeding the 60' limit.
I believe that the 60' constraint is also found within the SBCA Building Component Safety Information (BCSI) Guide to Good Practice for Handling, Installing & Bracing of Metal Plate Connected Wood Trusses; thus the engineer must prepare the engineering design and supporting calculations for the bracing as well as the trusses. Significantly more work.
Yep, but i missed that, i was responding to the clip.
Interesting thought: was the perfessor intending 60 ft of span (which he said) or 60 ft of building length?
I am not sure where he was going... He's had a couple posts bending my mind.
Inspector Gadget
Registered User
Still not following this discussion. Trusses are engineered elements. Trusses may or may not need bracing. If they need bracing, the designer/manufacturer gives plans to say "this is how it shall be braced."
Every truss plan is different.
I inspect trusses at the framing inspection. It's not difficult, nor remarkably time-consuming.
steveray
SAWHORSE
If the framer follows them it's not bad....I have had truss packets that are 1' thick with several girder trusses of different types and at least 10 different "typical" trusses....Rarely do they pass on the first try...
TheCommish
Registered User
trusses com with 3 bracing requirement, erection bracing genially supply by the truss manufacture, minimal standard bracing also supplied by the truss manufacture usually suppled as a hand out from BSCI, and truss specific bracing show on the truss drawings.
the handouts as I recall say the RDP should provide specific bracing requirement for each job and that the manufacture is responsible for the truss design form the top of wall up, not the attachment, support structure, earth quake, wind or earthquake transient to the walls below nor is the truss manufacture responsible for the gravity , snow and dead load support below the bearing locations
the handouts as I recall say the RDP should provide specific bracing requirement for each job and that the manufacture is responsible for the truss design form the top of wall up, not the attachment, support structure, earth quake, wind or earthquake transient to the walls below nor is the truss manufacture responsible for the gravity , snow and dead load support below the bearing locations
mtlogcabin
SAWHORSE
60 FT TRUSS SPAN INSTALLATION DANGERS
Question:
How do I, as a truss manufacturer, adequately advise my customer against the dangers of 60 ft. and over truss span installations?Answer:
IBC 2012 and 2015 include the following requirement:2303.4.1.3(link is external) Trusses spanning 60 feet or greater. The owner shall contract with any qualified registered design professional for the design of the temporary installation restraint/bracing and the permanent individual truss member restraint/bracing for all trusses with clear spans 60 feet (18 288 mm) or greater.
The recommendations in SBCA’s BCSI-B11 Summary Sheet are based on actual field experience but are only a guide for the qualified building designer, builder or erection contractor. It is not the responsibility of you, the truss manufacturer, to determine the exact handling, installing and bracing of the trusses you manufacture. Offer the summary sheet as a recommendation.
The summary sheet notes that for trusses over 60 ft., a professional engineer should be involved. This is because of the increased risk involved with trusses with large spans. When you achieve large spans like 60 ft. or more, temporary bracing becomes an extremely important issue! Hoisting 60 ft. and larger span trusses is also a challenge, and the summary sheet provides recommendations for this task as well (namely, that strongback/spreader should be used).
You should take extra caution with long span trusses. Know who is going to erect them, and go over the summary sheet with that contractor.
steveray
SAWHORSE
Yep...that is the section I was thinking of in post #10.....You and Commish nailed it in the world of "half a**" engineered building cautions...
60 FT TRUSS SPAN INSTALLATION DANGERS
Question:
How do I, as a truss manufacturer, adequately advise my customer against the dangers of 60 ft. and over truss span installations?
Answer:
IBC 2012 and 2015 include the following requirement:
2303.4.1.3(link is external) Trusses spanning 60 feet or greater. The owner shall contract with any qualified registered design professional for the design of the temporary installation restraint/bracing and the permanent individual truss member restraint/bracing for all trusses with clear spans 60 feet (18 288 mm) or greater.
The recommendations in SBCA’s BCSI-B11 Summary Sheet are based on actual field experience but are only a guide for the qualified building designer, builder or erection contractor. It is not the responsibility of you, the truss manufacturer, to determine the exact handling, installing and bracing of the trusses you manufacture. Offer the summary sheet as a recommendation.
The summary sheet notes that for trusses over 60 ft., a professional engineer should be involved. This is because of the increased risk involved with trusses with large spans. When you achieve large spans like 60 ft. or more, temporary bracing becomes an extremely important issue! Hoisting 60 ft. and larger span trusses is also a challenge, and the summary sheet provides recommendations for this task as well (namely, that strongback/spreader should be used).
You should take extra caution with long span trusses. Know who is going to erect them, and go over the summary sheet with that contractor.