Sun, November 28, 2004

Like a 'rainforest'

By Alan Cairns

MOULD LEFT by marijuana grow houses is "really scary stuff" and has to be removed with great care, specialists say. And while a proper environmental assessment and mould remediation job can be costly, dealing with it improperly can quickly turn a home into an environmental disaster.

"You are dealing with a saturation of humidity through the entire house for long periods of time," said Frank Haverkate, of Haverkate & Assoc. Inc. indoor environmental testing and consulting.

Haverkate, who has now tested 20 or so grow houses, says the extreme "rainforest-like" environment of a grow house typically creates mould in and behind drywall, on floor joists, in carpets and furniture and roofs.

If mould is found, Haverkate said, it must be treated with respect and should not be disturbed without containing the area to avoid the release of mould spores.

"Some construction companies have no idea what they are doing," Haverkate said. "Any monkey can put up drywall and remove the surface mould, but to do it properly takes expertise."

Haverkate has linked up with Mississauga-based engineer and mould inspector Darren Cooper, of Mould Scene Investigations (MSI) and Clean Lab Evaluation and Remediation (CLEAR).

Cooper cites as an example a high-end Markham house that was used as a grow-op for two years.

He said an insurance company and adjusters who had little insight into mould approved a basement cleanup. They did not believe the mould had spread to the second floor.

An inexperienced construction company failed to contain the mould, or seal the forced air heating vents. Airborne mould spores spread through the entire house.

Upon further inspection of the house two weeks ago, Cooper found masses of mould behind the upper bedroom walls.

Now all drywall, wood panelling, furniture, carpets, insulation and other porous objects have to be removed.

Wood floor and ceiling joists have to be blast-cleaned with dry ice and the entire roof must be removed.

The entire project will top $180,000.

Cooper said mould cleanup must see the creation of negative pressure in the house so mould spores do not blow around.

Mould has to be isolated, the heat vents sealed, and the removal and clean up must be done with specialized equipment.

Workers must wear contamination suits, gloves and boots at all times and use special breathing gear, he said.

Dr. James Scott, professor of environmental microbiology at the public health sciences department of the University of Toronto , agreed that grow houses are biologically "a mess."

Scott said a significant amount of mould on wallboard and other materials "can mean very costly renovations."

"It is not just as simple as a using a claw hammer and throwing it into a dumpster," Scott said.