The decision by the province to allow wood-frame residential buildings up to six storeys may leave future home buyers wet. Think of the leaky-condo crisis from the early 1980s through to the late ’90s.

Starting on April 6, British Columbia’s building code will enable developers to go beyond the current floor limit of four storeys. The change was announced January 14 by Premier Gordon Campbell as part of several measures to help the troubled forest industry.

Last year, the Architectural Institute of British Columbia and the Association of Professional Engineers and Geoscientists of British Columbia raised concerns over the integrity of the building envelopes of these taller wood structures.

In a letter to the Ministry of Housing and Social Development at the time, representatives of the two organizations pointed out that increasing building height “will likely result in higher environmental moisture loads due to higher wind forces and increased rain runoff collection areas”.

The letter, which was cosigned by Khash Vorell, chair of APEGBC’s building-codes committee, recommended additional research and tests, as well as the preparation of guidelines to address this particular concern.

In a recent phone interview, Vorell said that building envelopes “can be properly designed” to prevent moisture from seeping into six-storey wood structures.

“We’re currently writing a technical bulletin to address the issues that have been raised,” Vorell told the Georgia Straight.

However, the province’s poor record in putting up mid-rise wood buildings doesn’t offer much comfort that there won’t be a repeat of the leaky-condo disaster.

A study submitted more than a year ago to the Homeowner Protection Office showed that an overwhelming majority of housing units repaired due to water-penetration problems were made of wood.

Prepared by the consulting firm McClanaghan & Associates, the report noted that as of December 2007, a total of 24,535 units of wood-frame residential developments had been fixed using loans provided by the HPO, a provincial Crown corporation established in 1998 as a response to the leaky-condo crisis.

The number represents about 30 percent of 85,627 housing units constructed between 1982 and 1999 that used wood as the primary material.

By contrast, the report pointed out that 6,129 concrete units were repaired.

Architect Richard Balfour, director of the Metro Vancouver Planning Coalition, a sustainable-planning and urban-design think tank, has also pointed to the danger of higher wooden structures.

“The risk of leaky walls from wind driven rain is multiplied with exposure to greater heights, with now increased potential of upward water migration from wind driven forces,” Balfour stated in a letter e-mailed to Campbell and his B.C. Liberal cabinet on January 22.

Realtor John Grasty needs a lot of convincing that taller residential buildings won’t leak. He is the president of the Consumer Advocacy and Support for Homeowners Society, a group representing owners of leaky homes,

“There are potential fatal flaws because you now have a higher area exposed to wind-driven rain, which means that if the details are not done properly, there’s going to be all sorts of risks,” Grasty told the Straight.

For Grasty, the chance of having more leaky buildings is actually a “secondary” concern. He says that seismic and fire-safety issues are more serious matters that need to be resolved.

Jim Mutrie chairs a task force formed by the Structural Engineers Association of British Columbia and APEGBC to come up with design guidelines before the change in the provincial building code goes into effect in April.

One of the major challenges, according to Mutrie—former managing partner of Jones Kwong Kishi, a firm that provides structural-engineering services—is how to deal with wood shrinkage.

“Wood changes dimensions when the water content, the moisture content, of wood changes,” Mutrie told the Straight. “When you build a building in wood, it tends to shrink over the first few years of its life. If it’s not too many storeys, that’s not a big issue. But at six storeys, of course, it magnifies all these problems.”