November 7, 2008

Retrofitting of some B.C. schools involves simultaneous seismic upgrades and building envelope work to reduce susceptibility to water damage.

British Columbia school retrofit program draws on lessons learned from condo crisis

JEAN SORENSEN

correspondent

British Columbia schools are going through a multi-billion dollar upgrade aimed at halting any rot in the hallowed walls of learning.

Approximately 400 schools are currently being investigated and fixed through the provincial Ministry of Finance’s Risk Management Branch because they are suspected of having or have already developed leaky-condo syndrome. The total cost of fixing those found with building envelope problems could be as high as $377 million, executive director Phil Grewer said. Funding for the RMB’s building envelope program is coming from the B.C. education ministry.

This latest investigations comes hard on the heels of another major initiative focusing on upgrading B.C. schools to current seismic standards after several years of identifying at-risk schools.

The province has earmarked $1.5 billion over 15 years to earthquake-proof schools.

B.C. Building Envelope Council (BCBEC) vice-president Sophie Mercier said the two initiatives overlap. While the building envelope work is targeted at schools built in the leaky-condo era (1985 to 2000), seismic upgrades relate to earlier-era schools. If the seismic work requires the exterior cladding to be removed, then exterior re-assembly also involves the installation of a new rain-screen.

Fraser Valley’s Fricia Construction Inc. has done a number of seismic upgrades, finishing off Fort Langley Elementary, a 40-year old school, this summer but also adding a rain screen.

“The old wood was as dry as a bone,” when the exterior cladding was removed, said project manager Ron Vander Meulen.

“Because these older buildings were not that well sealed, the building envelope hadn’t failed.”

New masonry walls were added with a rain screen after the seismic work was finished to meet building code standards.

Leaky schools don’t surprise schools officials, building envelope engineers or contractors who have dealt with the issue as early as 2000.

“It’s just a continuation of the same problem,” said Mercier. “The reason it’s appearing later (in larger building like schools) is that the steel takes longer to corrode,” she said, referring to the first wave of wood condos.

Remediation essentially centres upon better water control. “Overhangs, flashings, canopies, and draining cavities for water and where dry air can circulate and more durable materials (like pressure-treated wood),” she said.

As well as material durability, “deflect, drain and dry,” are the design buzz words for building envelope construction today, said Greg McIntosh, building envelope division manager for Parksville’s Knappett Projects Inc., which has done a number of B.C. schools to date.

“We have done a lot more condos,” he said. But, the problems are essentially the same — the inability of the buildings to dry when moisture enters. McIntosh said his crew simply follows the directions set out by the building envelope engineers.

The main difference he has noticed (aside from the cavity) is detailing. “There is a lot more detailing to repel the water,” he said. Special attention is paid to windows and corners to prevent water ingress.

“All areas where there is possible penetration (joins, corners, and walls intersecting) are treated just like the windows,” he said.

Building sciences engineer Alex McGowan for Levelton Consultants Ltd., also investigates schools for leaks and has a track record of providing remedial work. He said the root of the leaky building crisis “has been a lack of respect or appreciation for the climatic conditions in B.C.”

“It is not a simple thing to design a building for this kind of climate,” he said. B.C.’s varied climate doesn’t lend itself to a “one size fits all”, he said, adding that water ingress can range from large amounts of rain as in the Lower Mainland or wind-driven rain on B.C.’s coast or simply condensation in northern areas from extreme cold outside and heat inside.

The key, he said, is to examine the damage done to the structure, whether it is a school or high-rise, determine the problem and plan remedial action accordingly. “A more robust rain screen may be warranted in some cases,” he said.

McGowan said the building codes determine a minimum requirement, but the building envelope consultant must decide whether those guidelines are adequate or whether greater efforts are needed to shield the building. Levelton is currently carrying out examinations of wind-driven rain on building envelopes for Canada Mortgage and Housing Corporation.

Project manager Ken White of Sawchuk Developments in B.C.’s Okanagan Valley agrees that climate plays a major role.

“We have architects who come here from the coast and they are designing something here that reflects the climate on the coast,” he said, adding that in 30 years of constructing and repairing structures — including schools — he’s not come across a case of building envelope failure because of rot or corrosion.

Print | Email | Comment