Know which outside opening brings air in.

A new planter or barbecue can fit neatly against the wall and still be in the wrong place. Before rearranging the side yard, identify the opening that supplies outdoor air to the house. Its surroundings become part of the air you bring indoors.

A house may have dryer exhaust, bathroom exhaust, ventilation intake and exhaust, and combustion-appliance vents. Similar weather covers can serve different purposes. Ask the installer to identify the ventilation pair, and keep a photo with the equipment record.

Where ductwork is visible, its labels and connection diagram can help confirm the route. Do not disconnect ducts, cover openings or use a flame or smoke to investigate. If the route disappears into a finished ceiling, the original installer or a ventilation contractor may need to trace it.

The applicable manual and local requirements govern placement. For example, Venmar and vanEE's Constructo/Solo guide specifies separation from exhaust outlets and other contamination sources, as well as clearance above ground. Those model-specific dimensions should not become a universal rule for every type of vent.

Health Canada's ventilation guidance identifies outdoor pollutant sources near intakes as a concern, including barbecues. Keep combustion equipment and its exhaust away from the incoming-air path. An open window nearby also deserves consideration.

• Move bins, stored materials and movable planters away from the intake's required clear space.
• Keep leaves and snow from covering the opening, using only safe ground-level access.
• Include the intake in plans for a deck, fence, driveway or outdoor cooking area.
• Report recurring exhaust odours or contamination rather than masking the smell indoors.

A seasonal change can matter even when the hood has not moved. A snowbank may rise in front of it, a vine may cover the screen, or a new fence may change the surrounding space. Take a fresh look after landscaping and exterior work.

An intact intake screen helps keep larger debris out; it is not a complete filter for smoke or gases. Do not add fabric, a finer mesh or a homemade cover without the equipment manufacturer's approval. Extra resistance can alter airflow.

If the intake is beside an unavoidable pollution source, ask for a location and system review. Give the contractor photos, the source's operating times and the ventilation model. Moving a hood can require changes to ducts, weather sealing and system balance.

For regional wildfire smoke, use the home's smoke-day plan and current public-health advice. That is a different situation from a barbecue beside the wall, but both start with knowing where outdoor air enters.