BC Assessment should have uploaded to the Online Dispute Resolution (ODR) website your property’s description and physical inventory (list of buildings and details such as size, number of rooms, etc.).  This is often called a Property Valuation Summary.

Verify that the information on your property is correct.  If not, describe to BC Assessment any apparent errors by sending a message in the ODR website.

If there is a physical problem with your property that significantly affects its value (for example, water damage), take photographs of the problem and get written confirmation from at least one reputable contractor that the problem exists as well as an estimate of the costs to repair.  Send a message to BC Assessment in the ODR website and attach supporting documents.

BC Assessment may want to inspect your property to see the issues for themselves and to see the condition of the remainder of your property.

You should also review the material in Do I have a strong case.