Question: Why did the government bring in this change?
Answer: There are a number of benefits to building with wood including lower costs and increased environmental sustainability. Increasing the allowable height of wood buildings is part of the Province's ongoing efforts to encourage innovative building practices and expand domestic markets for B.C. wood products. The new B.C. Building Code provisions allowing higher wood buildings maximize these benefits while maintaining the Province's commitment to public safety.
Question: How were these changes developed?
Answer: The development process for the mid-rise wood-frame residential construction code changes included:
Question: How did the Province consult?
Answer: The building industry, local government and fire officials have been involved from the very beginning. They have had opportunities to provide input through stakeholder information meetings, stakeholder technical advisory groups, an online consultation and correspondence with the Province. The online public review was held from November 13 to December 15, 2008 to give stakeholders and the general public a chance to comment on specific code change proposals. Feedback was considered in the adjustments made to the proposals to arrive at the changes to the BC Building Code announced in January 2009.
Question: What did the Province hear during the public consultation?
Answer: A variety of comments were received from every aspect of the building industry including local governments, builders, architects, engineers and fire officials. Support for the proposed changes ranged from 62 to 85 per cent, and as a result of feedback, modifications were made to strengthen the code requirements. All comments received were reviewed carefully before the changes to the BC Building Code were finalized.
Question: When will the limit be raised to six stories?
Answer: Starting on April 6, 2009, builders are able to build up to six storeys out of wood for residential buildings. The code change also allows 'hybrid' buildings with wood-frame upper storeys on top of a concrete or steel lower storey(s), provided the overall building height doesn't exceed the 18-metre height limitation. By announcing the change in January, people have had time to become familiar with the requirements before building begins.
Question: This work is happening quickly. Is the industry prepared to handle it?
Answer: While the Province has moved relatively quickly to allow mid-rise residential wood-frame construction, these changes have received a high level of scrutiny. Expert code consultants were hired to provide advice on the potential risks and the appropriate code changes to address them. The Province also conducted research and involved a wide variety of stakeholders including leading experts in a series of technical advisory groups.
The Province has changed the BC Building Code to provide an option for communities and developers who are prepared to build housing in a different way. The Province also recognizes that changing the Building Code is just one piece of the puzzle. Ministry staff is working closely with others involved in building - including local governments, designers and the insurance industry - to make sure they have the information they need to successfully apply the new Building Code provisions.
Question: Was this change put before the legislature?
Answer: It is not normal practice to put building code changes up for debate in the legislature. The Minister has authority, under Section 692 of the Local Government Act, to make changes to the Building Code by Minister's Order. This does not require a vote in the legislature. The Minister draws on the expertise of staff who work with the Building Code everyday, as well as technical advice and expertise from across the country and in B.C. before considering a change.
Through public review of proposed changes to the Building Code, the Minister consults thoroughly with those affected by changes - local governments, building and fire officials, builders, architects, engineers and others. For example, as part of the work to allow mid-rise residential wood-frame buildings, the Province held seven technical advisory group meetings and broadly consulted with those in the industry as well as the general public.
Question: How have these buildings performed in other jurisdictions where they are already being built?
Answer: Jurisdictions in the U.S. Northwest, where climate and seismic conditions are similar to B.C., have allowed mid-rise residential wood-frame buildings for a few years and these buildings have performed well. The Washington State Fire Marshall noted that the Fire Department had reviewed and was supportive of the mid-rise Building Code amendment in their jurisdiction. The Fire Marshall also noted that jurisdictions that had adopted five-storey wood-frame construction (which are higher than the buildings B.C. allows when the concrete first floor is taken into account) had not experienced any negative impacts.
In B.C., the process for making code changes has included advice from stakeholders and technical experts on how to deal with the challenges of higher wood-frame construction in the context of the BC Building Code - which is different from the codes to which U.S. buildings are built.
Question: What sort of training and education will be available?
Answer: The Province is working with some key industry stakeholders to identify and facilitate education and training for Building Code users to make a smooth transition to the new requirements. Through a partnership with the Association of Professional Engineers and Geoscientists, Architectural Institute of B.C. and the Homeowner Protection Office, new guidelines have been developed to assist designers wishing to build mid-rise residential wood-frame buildings. A B.C. demonstration project is also being planned, which will help educate designers, builders and local governments on the techniques and materials involved in building safe mid-rise residential wood-frame buildings.
Question: How big are mid-rise residential wood-frame buildings?
Answer: Mid-rise residential wood-frame buildings are limited to 7,200m2 of gross floor area. This is 80 per cent smaller than noncombustible residential buildings which can have up to 36,000m2 of gross floor area. The gross floor area or building volume will not increase, just the height. The floor plate becomes smaller with each additional storey (see example below).
Firewalls can be used to separate mid-rise residential wood-frame buildings within one larger structure (see example below).
Question: How is the maximum height of a mid-rise residential wood-frame building measured? How is the height of a storey defined?
Answer: As with the height restrictions for all buildings in the Building Code, building height is the number of storeys above ground. The height of individual storeys is not regulated but residential buildings with floors more than 18 metres above grade are classified as high buildings and must comply with significant extra safety provisions. Mid-rise residential wood-frame buildings must be less than 18 metres to the top floor.
Question: How are the new energy and water provisions in Part 10 of the BC Building Code applied to mid-rise residential wood-frame buildings?
Answer: Part 10 of the BC Building Code requires all residential buildings exceeding four storeys to conform with the ASHRAE 90.1 Energy Standard. This applies to five and six storey wood-frame residential buildings. The water efficiency provisions of Part 10 apply equally to all buildings, regardless of height.
Question: Mid-rise residential wood-frame buildings require non-combustible cladding. What are some common choices for exterior cladding?
Answer: Stucco, masonry, metal, fibre cement siding, and vinyl siding over gypsum board are commonly used and acceptable non-combustible cladding materials.
Question: How is fire safety being addressed?
Answer: The Office of the Fire Commissioner (OFC) is satisfied mid-rise residential wood-frame buildings built to these new BC Building Code provisions include the most stringent fire safety requirements of any form of construction in B.C. Many of the code changes, such as a noncombustible cladding, are specifically designed to manage fire risks. Because these buildings are taller than four storeys, they are required to meet a higher standard of sprinklering. While developing these changes, the Province brought together experts and leaders in the fire service at several technical advisory group meetings to help fully understand their concerns and work with them to develop solutions. The Province is working with communities to ensure fire officials have information about the recent changes.
Question: What fire resistance rating is required for mid-rise residential wood-frame buildings?
Answer: One-hour fire resistance rated assemblies are required.
Question: Do mid-rise residential wood-frame buildings require fire suppression sprinkler systems?
Answer: Yes. These buildings exceed the height limits for the NFPA 13R sprinkler systems required for four-storey wood buildings. Five and six-storey buildings require full NFPA 13 systems, including sprinklers for attics and balconies.
Question: How do fire fighters extinguish fires in mid-rise residential wood-frame buildings?
Answer: These are compartmentalized, fully sprinklered buildings with standpipe systems designed for interior firefighting.
Question: How is fire risk addressed during the construction phase of mid-rise residential wood-frame buildings?
Answer: The BC Fire Code requires fire safety measures, including a fire safety plan, to be in place at construction sites. Based on expert advice, construction phase fire risks are not expected to increase with for higher wood buildings since the total allowable volume of the building will remain the same.
Question: How is earthquake safety being addressed?
Answer: As part of B.C.'s continuing commitment to safety, the Province is partnering in leading edge research to generate the most up-to-date information on how wood-frame buildings perform in an earthquake. The Province is conducting research based on the seismic conditions experienced in the Pacific Northwest. BC is a partner with the National Science Foundation (US) in the NEESWood project. The Network for Earthquake Engineering Simulation (NEES) is a consortium of leading seismic experts from 15 university labs across the United States.
The NEESWood project is comprised of:
This ongoing research provides the most up-to-date information about how wood-frame buildings perform in an earthquake, so British Columbians can be confident their homes will continue to meet the Province's high standard for safety.
Question: Why did the Province add a new set of seismic safety requirements on April 3?
Answer: Based on new information from computer model analyses of seismic performance, the Association of Professional Engineers and Geoscientists of BC (APEGBC) concluded at the end of March 2009 that, in addition to the code change enacted in January, more was needed to ensure a reasonable level of assurance of seismic safety risk. So the Province took immediate action to protect public safety by strengthening the seismic safety provisions.
This analytical work was part of the development of the seismic design technical bulletin by APEGBC in preparation for implementation of the code change. While the analysis process took more time than originally anticipated, the changes were made in time to ensure structural designers have appropriate information to achieve seismic safety.
Question: Will this lead to another leaky condo problem?
Answer: The BC Building Code contains stringent performance standards for building envelopes regardless of the size of the building. This has not changed. The recent additions to the code include an appendix note reminding building designers to account for wood shrinkage due to changes in moisture content, and coordinate wood shrinkage calculations among the designers of all building elements such as elevator shafts and exterior cladding.
A Technical and Practice Bulletin on Structural, Fire Protection and Building Envelope design for mid-rise wood frame buildings has been prepared by the Association of Professional Engineers & Geoscientists BC (APEGBC) in collaboration with the Architecture Institute of BC (AIBC) and the Homeowner Protection Office with the financial support of the Building and Safety Standards Branch.
Question: How is wood shrinkage managed?
Answer: The construction industry in BC has experience in managing shrinkage issues in four-storey wood buildings. The recent additions to the building code include an appendix note reminding building designers to account for wood shrinkage due to changes in moisture content, and coordinate wood shrinkage calculations among the designers of all building elements such as elevator shafts and exterior cladding. A Technical and Practice Bulletin for engineers and architects has been developed with the construction industry to address shrinkage, including differential shrinkage in buildings of mixed construction (i.e. concrete/steel and wood). This will include measures to control the moisture content of wood before and during construction.
For more information, contact the Building and Safety Standards Branch: Building.Safety@gov.bc.ca
