For proper venting in an attic or roof, a home should have both high and low venting. The best low venting is usually soffit vents, as they can be installed at the lowest point of the roof to optimise air movement in the attic space. A soffit is the overhang on your roof. Soffit vents are installed under this overhang to allow air to flow up and out of the attic, which can lower energy costs and is needed to reduce the possibility of mould growth.
Remove any insulation that may be located in the soffit area where you plan to add vents. It is easiest to do this from inside but not always possible. Pull the insulation out from the holes that you will be making for venting, if necessary.
Hold the soffit vent up to the soffit and mark the outside edges lightly with a pencil. Within that area, use a hole saw to drill through the soffit and into the attic space.
Make three holes, evenly lined up with each other, using the hole saw. Use a reciprocal saw to cut from one hole to the next to create one, large opening.
Screw the soffit vents in place using the screws provided. A screw should be at each corner of the vent and midway along each side of the vent to secure it completely.
Use a clear silicone caulk, or one that matches the colour of your soffit vents, to caulk around the outer edges of the vent. This further limits the chances of bugs or small animals entering the space.
Approximately 60 per cent of attic ventilation should be low ventilation.