Landlords who unwittingly allow their houses or condominiums to be used as illegal drug factories will have a tough time selling those properties in British Columbia. Grow homes have been added to the province's Property Disclosure Statements, which means sellers must declare that the homes have been used to grow marijuana or to manufacture illegal drugs. For new homes and condominiums, home warranties are being suspended for grow-op houses.

The province's Property Disclosure Statement, introduced in 1990, is a standard form that must be completed by the seller when the home is listed for sale. It asks questions about the condition of the property to help potential buyers make informed decisions. The new question on the form asks if the seller is aware if the property has ever been used as a marijuana grow operation or to manufacture illegal drugs.

"Grow ops and illegal drug operations can produce property defects and other hazards that are major concerns for the public," says David Herman, president of the British Columbia Real Estate Association.

Marijuana cultivation operations require much more electricity than a typical residential home. Illegal electrical hookups pose a serious safety risk for those in and near the home. A police report called Green Tide, recently issued in Southern Ontario, says the likelihood of a fire in a grow-op dwelling may be as much as 40 times greater than in a typical residence.

The report also says that "human health risks can result from the mould sometimes associated with marijuana hydroponic cultivation, the chemicals used to foster plant growth, and the relatively high concentration of carbon dioxide and carbon monoxide suspected to exist in some grow-op dwellings. Many of these safety concerns are exacerbated by the fact that grow ops are generally located in highly populated regions."

Recently police in Richmond Hill, Ontario received a silent 911 call from a nine-year-old child at a home. When they arrived at the house, they discovered a grow operation and seized 22 marijuana plants, 122 stems hanging to dry, and more dried and packaged marijuana in a fridge. The home had six children in it who were sleeping on urine-soaked mattresses with no sheets on the bed, police said.

Police told reporters that pesticides and fertilizers were sprayed on the plants, but with no ventilation in the home it creates serious indoor air quality problems, which can cause headaches, dizziness and upper respiratory problems.

The Green Tide report on indoor marijuana cultivation says that during the last three to five years, grow operations have proliferated in southern British Columbia and in Southern Ontario. The report says that between 2000 and 2002, the number of grow ops in Ontario is estimated to have increased by more than 250 per cent, and that in 2002 alone, as many as 15,000 grow ops were active in Ontario.

The Organized Crime Agency of British Columbia says that organized crime controls 85 per cent of the marijuana cultivation and distribution in B.C.

With the increasing number of new homes and condominiums being used for grow-ops, the companies who offer home warranties in British Columbia have begun suspending coverage on homes identified as grow-ops. Since 1999, all residential builders in B.C. must arrange for home warranty insurance before they can obtain a building permit. The legislated home warranty insurance covers two years on labour and materials, five years on the building envelope and 10 years on the structure.

But homes that have been used for uses "other than residential" can have exclusions to their warranty. Since the houses can become damaged by the moisture, mould, bad wiring or other alterations made for a grow operation, companies that provide the warranties are sending inspectors to the homes, and then suspending coverage in whole or in part. In some cases, the houses can be repaired and returned to full warranty status.

How can you tell if there's a grow-op house in your neighbourhood? The Delta, B.C. police say to look for these tell-tale signs:

• The house does not look lived in or residents are seldom seen (garbage is rarely put out to the curb).

• The house windows are always covered to prevent the escape of bright hydroponic lights.

• Heavy condensation can be seen on the windows.

• There's a strange odour emanating from the house (pungent and skunky).

• Humming noises, such as those made by a fan, are heard.

• There's excessive vehicle and/or pedestrian traffic day or night at unusual hours.