Mould around the dryer vent in an Ottawa laundry room?

Mould around a dryer vent is a moisture problem first. Before anything else, find and fix the source: possibilities to check include whether the vent duct runs all the way outside, whether the exterior flap opens freely when the dryer runs, and whether condensation is collecting inside the duct or behind the wall. Cleaning the mould without fixing the airflow will bring it back.

How serious is it?

Health Canada's size bands tell you how to handle the cleanup. A small area is one to three patches, each less than one square metre. A medium area is more than three patches, or patches greater than one square metre but less than three square metres. An extensive area is a single patch larger than three square metres. Health Canada says you can generally clean small and medium sized areas yourself, and recommends getting professional help with extensive mould growth.

If the patches around your vent are small or medium, the practical steps are to fix the moisture source, clean the affected surface, and keep the area dry going forward. If the growth is extensive, a qualified professional should assess and clean it up.

One thing to check before you cut into anything: if your laundry room is in an older home, the wall, ceiling or floor materials near the vent may contain asbestos. Health Canada advises hiring a professional to test before renovating and a qualified asbestos removal specialist if asbestos is found. Ontario's guide lists textured paints and coatings, joint compounds and vinyl flooring among materials that may contain asbestos, and says many such products stayed in use until the mid 1980s. If a professional needs to open the wall to inspect the duct, ask about testing suspect materials first.

If you do bring in a mould remediation contractor, a fair quote should cover:

• A clear description of the area to be cleaned and how the moisture source will be addressed
• What happens if mould is found inside the wall cavity once it is opened
• Whether any building materials will be removed, and how the debris will be handled
• Confirmation that the vent duct will be inspected or replaced as part of the scope

We found no Ontario statute or regulation that licenses mould remediators or sets indoor mould limits, so the scope of work and the method are things to settle in writing before work starts. You can also search a contractor's WSIB clearance online before signing.

The most useful question to put to any contractor you are considering: if they open the wall and find mould has spread further than expected, what is the process and the cost for expanding the scope?

To get quotes, the form on this page goes to local contractors listed in the Ottawa Construction Network directory.