Repairing a cannabis grow house

This guide provides information about cannabis (marijuana) grow houses. It describes the types of damage and potential health hazards to be aware of and how these can be addressed to ensure safe further habitation.

The obligation to ensure that a property is safe for human habitation is the responsibility of the property owner, or a property manager on the owner’s behalf.

What is a cannabis grow house?

A cannabis grow house is the term used to describe a property that has been used illegally to grow cannabis.  The property damage from this illegal activity can occur on a large scale and involve potentially illegal and unsafe structural modifications, improvised lighting, irrigation, ventilation as well as unsafe modification of electrical systems.

Police role after identifying a cannabis grow house

When a grow house has been identified,  police will remove plants, illegal drugs, all critical equipment, and protect against any major physical hazards as part of their normal operating procedures. Where the power supply and wiring have been illegally modified, Western Power will normally attend and shut off power to the location.

Process of notification and management 

The notification and management process for cannabis grow houses is usually as follows:

  • Police action is undertaken. Following this, the Department of Health (DoH) and relevant Local Government Authority (LGA) are notified of the property details.  
  • DoH liaises with LGA as necessary.
  • LGA Environmental Health Officers (EHO) may conduct an inspection of the property and may involve other LG officers such as Building Surveyors as required. 
  • The LGA may recommend or require the property owner to address any damage that has occurred and ensure the property is kept secure.
  • LGA may issue a Notice of Improvement on the property for the repairs necessary to make the property safe for human habitation under the Health (Miscellaneous Provisions) Act 1911. Failure to respond to a Notice is an offence under the Act.
  • The owner of the property should ensure the building is inspected and certified for safety of entry prior to any clean-up or repair activities.
  • If the repair is prompted by a LGA Notice of Improvement then completion of the work should be reported to the LGA.

Safety issues

Following the confirmation that a property has been used as cannabis grow house, the most significant health risks to consider are as follows:

  • safety issues due to the structural condition of the house, e.g. electrical modifications
  • exposure to spores from mould growing inside the residence. Inhaled mould spores can cause a range of respiratory and allergy problems, and risk increases if there are any physical disturbing activities at the time, such moving furniture
  • occasionally residues from pesticides, trace elements found in fertilisers, and other volatile drug residues may be found 

As a precaution Personal Protective Equipment (PPE) is advised for anyone entering or working inside a cannabis grow house, such as a dust mask, robust boots and disposable gloves.

Potential damage to properties

Areas that have extensive water damage and mould, including internal structures such as ceilings, furniture, floors, walls, footings, plumbing, electricity and other internal fittings, may need to be removed and replaced or repaired.

Fixing the damage may require professional services such as:

  • a clearance statement from a qualified  building inspector
  • plumber to replace water appliances or drains to sewer or leach drain
  • electrician to ensure power supply is legal and safe
  • carpenter and plasterer  to replace walls, floors and/ or ceilings
  • a licensed asbestos removalist for damaged walls or roof structures containing asbestos
  • industrial cleaner with access to industrial dryers and HEPA filters on vacuums.
  • The repair and clean-up can be a long and potentially expensive process.

Signs of a potential cannabis grow house or other illicit activities 

The following indicators may alert people to the possibility of a property being used as cannabis grow house or for other illicit activities:

  • house not lived-in, or toys left outside when children are not living there
  • unusual coming-and-goings, for short-terms but frequently
  • constant noise such as fans running or electrical humming, especially at night
  • covered windows – heavy plastic or curtains pressed against windows
  • condensation may produce mildew or rot or water marks near windows and foundations
  • occasional power surge or power drop in neighbouring homes
  • odd odours – sweet vegetation, pine smell, or rotting cabbage
  • history of use as drug house or cannabis grow house
  • mail mounting in the mailbox, lights left on, constant radio playing or TV left on

Landlords who suspect the property is being used for illegal purposes should contact Crime Stoppers on 1800 333 000 or use the online form (external site).

Useful Resources

For information on the treatment of mould 

More information

Department of Health

Phone: (08) 9388 4999

This publication is provided for education and information purposes only. It is not a substitute for professional advice. Information about a service, product or treatment does not imply endorsement and is not intended to replace professional advice. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified professional for answers to their questions.