SFIA gives Webinar on the Risks of Wood Framing/Code Changes

The Steel Framing Industry Association is a USA-based sister organization to the CSSBI. As we have seen similar code changes for combustible materials in Canada, this webinar touched on many of the same concerns the steel and concrete industries have expressed in Canada.

This last Thursday the SFIA Professional Development series featured an online presentation by Chief Steve Lohr, currently the Fire Chief of Hagerstown, MD and who recently retired as Chief of the Montgomery County, MD Fire and Rescue Services.  Steve has recent, first-hand experience fighting a mid-rise wood-frame fire and he’s agreed to testify before a committee of the Maryland State Legislature about the dangers these structures represent.

Watch the video to see a clip reporting on the 2014 fire that destroyed the Upper Gables apartments in Rockville, MD.

Cas d'étude: Programme d’amélioration des installations sportives – l’acier, un choix évident

Projet: George Brown College

Toronto, ON

Le gymnase du collège George Brown de Toronto avait désespérément besoin d’être modernisé. Construit initialement dans les années 1970, le gymnase devait être rénové. « Tout l’équipement se trouvait dans un petit espace dépourvu de lumière naturelle. Seuls les rats de gymnase s’en servaient », selon M. YewThong Leong, architecte principal de SSG Architecture. « On nous a demandé d’ajouter une annexe au gymnase. Les besoins du collège en matière d’activités récréatives ont changé. Ils voulaient notamment un studio pour le yoga. »

Une charpente en acier léger a été choisie en raison de ses propriétés de construction non combustibles, de son poids léger et de sa capacité d’intégration à la nouvelle structure. L’acier permet de personnaliser facilement l’ensemble de la charpente et des éléments afin de s’harmoniser avec les écarts d’espacement de la structure historique.

L’ajout d’une annexe moderne à un bâtiment historique a constitué l’un des défis de ce projet. « L’annexe d’un immeuble historique se doit d’être construite de telle sorte qu’il soit possible de la retirer, et l’acier est parfait pour ce faire », indique M. Leong. « Le nouvel immeuble est entièrement construit en acier. » 

Les impératifs du calendrier de construction ont imposé l’érection de la superstructure pendant l’automne et la saison hivernale. Du fait de l’emploi d’une méthode de construction à sec, l’installation hivernale représentait une solution sûre. La préfabrication des composants a permis de poursuivre en toute sécurité les travaux de construction, tandis que le bâtiment actuel était utilisé par le personnel et les étudiants.

Il ajoute également que l’acier a été choisi pour sa solidité et son poids relativement léger. « Tout l’acier est découvert. Nous voulions que le design présente un certain degré d’honnêteté. L’acier a été peinturé de couleur blanche. Cela donne un effet de halo avec la lumière externe, le bâtiment semble tout simplement rayonner. » 

La construction de l’annexe a pris fin l’an dernier. Il s’agissait de la troisième et dernière phase du plan d’amélioration des installations sportives. « L’acier n’a pas un aspect lourd comme le béton. Le recours à l’acier donne un effet de légèreté à l’ensemble », selon M. Leong. « L’annexe est superbe. Elle offre une vue incroyable et profite de beaucoup de lumière naturelle. Ce bâtiment a été très bien reçu. » 

L’ajout offre tout l’espace nécessaire pour élargir les programmes existants de musculation et d’activités cardiovasculaires qui ont actuellement cours au même étage dans un endroit dépourvu de fenêtre du gymnase des années 1970. Une fois les installations existantes déplacées, l’espace a été rénové pour en faire une nouvelle salle de vélo et des studios pour les classes d’exercice.

Le nouvel espace est beaucoup plus convivial et cela incite beaucoup d’étudiants à s’entraîner au collège. « La faculté a fait quelques changements. Finalement, l’annexe sert de salle de musculation et compte de nombreux appareils cardiovasculaires. Le studio de yoga figurait mieux dans le bâtiment initial » explique M. Leong. « L’annexe attire une autre clientèle. C’est une réussite et nous en sommes bien heureux. »

ÉQUIPE DE CONCEPTION ET DE CONSTRUCTION 

CLIENT : George Brown College 

ARCHITECTE : SSG Architecture Inc. 

INGÉNIEURS DE STRUCTURES : Milman and Associates 

ENTREPRENEUR GÉNÉRAL : The Michael Thomas Group Inc. 

FOURNISSEUR DES CHARPENTES MÉTALLIQUES LÉGÈRES : Bailey Metal Products 

INSTALLATEUR DE CHARPENTE MÉTALLIQUE LÉGÈRE : Orient Construction Limited 

FOURNISSEUR DU PLATELAGE EN ACIER : Canam Group 

ENTREPRENEUR DE CHARPENTES MÉTALLIQUES : Pengelly Iron Works 

FOURNISSEUR DE REVÊTEMENTS EN ACIER : Vicwest

Cliquez pour télécharger cas d'étude #90-15: Programme d’amélioration des installations sportives – l’acier, un choix évident

Project Profile: Athletics Facility Enhancement Program – Steel was the obvious choice

Project: George Brown College

Location: Toronto, ON

The gymnasium at George Brown College in Toronto was in desperate need of an upgrade. Originally built in the 1970s, the gym was due for an overhaul. “All the exercise equipment was stuck in the same small space with no natural light. The only people who used it were gym rats,” says Yew-Thong Leong, Principal Architect with SSG Architecture. “We were asked to put an addition adjacent to the gym. The college’s recreational needs had changed. They wanted a yoga studio, among other things.”

Light steel framing was selected for its noncombustible construction properties, lightweight and its ability to integrating with the new structure. Steel allowed for easily customizing all the members and elements to align with the in congruencies of the historic structure’s differential grid spacing.

One of the challenges the project posed was the need to add a modern addition to a historical building. “When you’re building an addition to a historical building, you have to do it in such a way that it can be removed, and steel allows for that,” Leong says. “The new building is entirely made of steel.”

The construction schedule dictated that the super structure would be erected during the fall and through the winter months. A dry construction method made winter installation a safe possibility. Prefabrication of components allowed for construction to continue safely while the existing building is occupied with staff and students.

He adds that steel was also chosen for its strength and relatively light weight. “We left all the steel exposed. We wanted there to be a level of honesty about the design. We painted the steel pure white. It has a halo effect from the amount of light coming in – it simply glows.”

Construction of the addition was completed a year ago. This latest addition was the third and final phase of the Athletics Facility Enhancement Plan. “Steel doesn’t look as heavy as concrete. The use of steel added a lighter feel to the space,” says Leong. “The addition is amazing. It has incredible views and lots of natural light. It’s been very well received.”

The addition provides space for the purpose of expanding the programs for the existing weight lifting and cardio facility which is currently housed in a window-less space within a 1970s gymnasium addition on the same floor. Once the existing facilities were vacated, they were renovated into a new cycle room and studios for movement classes.

The new space is a lot friendlier, and it’s encouraged more students to work out at the college, he says. “The faculty bumped a few things around. In the end, the addition became the weight-training room, with a lot of cardio machines. The yoga studio was better suited to the original building,” Leong explains. “The addition has brought out a different population. It’s quite well done, and we’re very happy about it.”

DESIGN AND CONSTRUCTION TEAM 
CLIENT: George Brown College
ARCHITECT: SSG Architecture Inc.
STRUCTURAL ENGINEERS: Milman and Associates
GENERAL CONTRACTOR: The Michael Thomas Group Inc.
LIGHT STEEL FRAMING SUPPLIER: Bailey Metal Products
LIGHT STEEL FRAMING INSTALLER: Orient Construction Limited
STEEL DECK SUPPLIER: CanamGroup
STRUCTURAL STEEL CONTRACTOR: Pengelly Iron Works
STEEL CLADDING SUPPLIER: Vicwest

Click to download Case Study #90-15: Athletics Facility Enhancement Program – Steel was the obvious choice

Fire Endurance of Floor Assemblies

The National Building Code of Canada (NBCC) is the model code that specifies the structural and fire protection requirements for buildings constructed across Canada. These requirements prescribe the minimum levels of occupant safety to be achieved.

Steel construction has a long history of implementing standards and conducting tests to meet these codes. The latest series of tests have produced new fire-resistance ratings for floor assemblies using cold formed c-section joists, suitable for constructing houses and small commercial and industrial buildings. 

Steel construction has sometimes been unjustly perceived as offering reduced fire safety. Testing conducted by the National Research Council of Canada (NRC) - Institute for Research in Construction (IRC) in Ottawa, provides an indisputable third party endorsement that cold-formed steel framed floor assemblies can meet and exceed the building code requirements, and in fact out-perform the more traditional framing materials. 

Testing Program 

The fire testing conducted by NRC/IRC was part of a three year joint government and industry program. The project participants included representatives from the steel, wood and concrete industries, gypsum board and insulation manufacturers, home builders and related government agencies. Thirty-two fire tests were conducted on full scale floor assemblies framed using dimensional lumber, wood-I joists, concrete and cold-formed steel joists. Testing was done in accordance with fire endurance testing standards CAN/ULC-S101-M89 and ASTM E119. 

The time temperature curve that is specified in the CAN/ULC and ASTM standards was adhered to in all tests. The test standards also called for the floors to be loaded to 100% of strength. This was the case for all the steel framed floors and some of the wood and wood-I floors. 

Results 

In the following table, the test results show that the steel framed floors achieve a higher fire resistance than either of the wooden counterparts. For the same floor assembly construction (see Figure 1), and switching only the floor joists, the cold-formed steel joists achieved a fire resistance of 74 minutes while the dimensional wood joist achieved a rating of 69 minutes under the same loading conditions. The wood-I framed floors reached 72 minutes and the fire resistance was found to depend on the type of wood-I joist used. The effect of imposed test load was found to be significant. For the solid wood joist increasing the load from 75-100% decreased the fire resistance by 14%. The failure mode for all the floors in this comparison was structural. 

The data, published by the NRC/IRC in an internal report (IRC-IR-764), will form the basis for fire resistance ratings for floor assemblies to be listed in the NBCC. The tests outlined in the following table are baseline tests from which the various effects of insulation and resilient channel can be extrapolated. The data will eventually enable derivation of fire resistance ratings for unlisted assemblies according to the component method found in Appendix D of the NBCC. The steel industry, through the Canadian Sheet Steel Building Institute, has already developed a large series of non-loadbearing cold-formed steel framed wall assemblies that achieve the required fire-resistance and acoustic ratings and these are listed in the NBCC Part 9- Table A-9.10.3.1.A.

Click to download Technical Bulletin Volume 1, Number 2: Fire Endurance of Floor Assemblies.

The Steel vs. Wood Debate

With the recent changes to the Ontario Building code allowing combustible construction materials for buildings up to 6 storeys high, there is a lot of information out there speaking about the various benefits and disadvantages of materials like concrete, wood and steel.

The Multi-Housing News Online posted an article last week Why Cold Formed Steel is a Viable Alternative to Wood Frame Construction written by Charles Specht, CIC, CDA, Constructive Risk.

In this article Charles writes about some of the major fires that occurred in 2014 in the United States at various wood framed building projects. He uses these examples to discuss the impact of building material choices on things like the cost of Builders Risk Insurance.

Insurers have long been wise to these risks. “Wood” construction has a greater likelihood to burn or be damaged by fire and will be a total loss versus a partial one. Loss history for wood construction has been poor, and carriers are very restrictive of the amount of risk they will take. This drives up the cost to the builder, and actually weakens the pro-wood argument that it is less expensive than other materials. The recent major wood frame fires calls for a need to look at cost savings and particularly insurance more closely.

He says in the article that steel framing is a viable alternative to wood framed construction as it is inherently non combustible and can qualify for lower Builders Risk Insurance costs. He also talks about the other benefits of steel framing such as durability, moisture- and mold-resistance and recyclability.

Click here to read the whole article and visit the CSSBI website to download all the resources and information you need to design and build in cold formed steel framing.

Application of UL Fire Resistance Ratings in Canada

The National Building Code of Canada, Part 3 on Fire Protection, Occupancy Safety and Accessibility, requires the fire resistance ratings for assemblies to be determined on the basis of tests conducted in accordance with CAN/ULC-S101 “Fire Endurance Tests of Building Construction and Materials”. S101 is a Canadian test standard used by agencies like Underwriters’ Laboratories of Canada (ULC) to conduct fire testing of building components. ULC listings have been used by Canadian design professionals for many years to select fire rated building assemblies, but there is another source for listings that significantly increases the available options: these are the Underwriters Laboratories Inc. (UL) tested assemblies.

It was always possible to use the UL listed assemblies in Canada, but questions were raised about the equivalence of the UL tests to the requirements of CAN/ULC-S101, and in particular the impact of UL loads calculated using Allowable Strength Design instead of Limit States Design as required in Canada. To address this difference in design approach, the UL designs included a “load restricted factor” (LRF) to reduce the design load for Canadian applications.

Working with UL and ULC, representatives of the Steel Framing Alliance, Canadian Steel Construction Council and the American Iron and Steel Institute were successful in getting adopted a LRF of unity for load-bearing cold-formed steel wall and floor assemblies listed in UL’s directory. Having no load restriction is possible because the calculation of the member resistance in Canada and the U.S. is based on the same standard: CSA S136-07 or ANSI/AISI S100-07, “North American Specification for the Design of Cold-Formed Steel Structural Members”.

Prior to this development, only assemblies that were ULC rated were readily accepted, and because very few tested assemblies were listed in their directory, cold-formed steel faced a significant barrier to entry into the mid-rise construction segment. With the removal of any load restriction, about 30 UL fire-rated load-bearing wall assemblies can now be used in the Canadian market. This LRF can only be applied to load-bearing wall assemblies tested with laterally braced steel studs which account for the majority of UL listed assemblies. In comparison, a more conservative factor of 0.82 and 0.65 must be applied to wood framed walls and floors respectively.

For More Information from UL
For more detailed information, please refer to UL’s website (www.ul.com) and open “BXUV7.GuideInfo” (on the bottom of their homepage, click on “Certifications”, then entre BXUV7 in the “UL Category Code” box and click search, then click on the “link to file” BXUV7.GuideInfo). For more specific help, contact the Standards and Codes Consultation Services staff at ULC through their website at www.ulc.ca.

Click to download Technical Bulletin Volume 1 Number 3: Application of UL Fire Resistance Ratings in Canada