Although it doesn't happen too often, when a grow-op is under way in a rental unit it can cause irreparable damages. Recently here in Calgary, a landlord has sued a tenant for $105,000 in damages. Inside the basement, plastic was found covering the bedrooms and there were approximately 100 lamps providing light for the operation. As well, the walls had several holes in them so that air could be vented outside.
With this type of grow-op, a lot of carbon dioxide is produced along with high heat and humidity. This is the perfect environment for mold to grow in and all of this humidity can cause a lot of damage to the home. The landlord in this case ended up selling his property at a loss to a developer. It was eventually torn down so that a new home could be built in its place.
Helpful advice for landlords
This landlord did screen his tenants before allowing them to move into the building. Everything checked out properly and he felt that the tenants were going to be responsible renters. References were checked and everything looked good.
The one thing that can be learned from this horrifying experience is that a landlord should be physically checking out his property from time to time. Even when a tenant has what seems to have perfect credentials, you just never know.
The best way to avoid having a grow-op running in one of your rental buildings is to write in the lease that physical inspections will be carried out. Even though you'll have to give a 24-hour notice to enter the unit, the tenant won't have time to clean up the space and remove the odour before you arrive.
If you can't carry out these physical inspections, hire someone that can do them for you. This will help to deter prospective grow-op tenants from signing a lease in your building.