How to finish a basement properly


Published on January 30, 2017

Finishing a basement can be a cost effective way to add square footage to your living space.

But before you begin there are lots of things to think about. As with any substantial investment to your home you want to make sure the job is properly planned and executed. This week we’ll talk about some safety considerations, next week we’ll move onto controlling moisture and some aesthetic subject matter.

Structural Changes – If you are looking at finishing a basement you need to get a building permit if you plan to make any structural changes or install a bedroom. If you plan to put a bedroom in your basement, be aware that building code requires bedrooms to have at least one window that can be opened from the inside without tools or special knowledge. This is to make sure that in the case of an emergency, a means of egress is available. Egress windows must have a minimum unobstructed opening of 3.8 sq. ft., with no dimensions less than 15”. The simplest way to meet egress requirements is to extend an existing window downwards so that it is taller. In addition, a minimum of 1’-10” must be provided in front of windows that open into a window well for escape in emergencies. Always check for buried utilities such as gas, water, electrical, sewer, etc. before starting to dig the window well.

If you are looking at adding a whole new window to your basement certain precautions must be taken. When removing a section of foundation wall, you may have to install a beam (otherwise known as header) to provide extra support. Depending on the size of window, a temporary support wall may be required when cutting a foundation wall that is weight-bearing (e.g. perpendicular to the floor joists). Always make sure you use a certified carpenter when undertaking work that may potentially impact the structural integrity of your home.

Radon Gas – Toxic gases are another thing to consider before finishing a basement. Radon gas is naturally occurring and its presence varies by location depending on geological formations. The province of Nova Scotia issues a map that shows radon potential in Pictou County falls mostly in the low- to medium-risk categories. Testing is the best way to determine if there is radon in your home. Do-it-yourself radon testing kits can be ordered online from the Lung Association of Nova Scotia.

When radon enters an enclosed space such as a basement it can accumulate to high concentrations that are hazardous to health. Since 2010, building codes require new homes to have a permeable layer under the slab overlaid by a vapour barrier. A capped vent stub must also be installed through the slab as a rough-in for a radon reduction system if required down the line. If radon levels are found to be above acceptable levels, an active soil depressurization system can be installed. This entails a pipe installed through the foundation floor with an attached fan to draw radon from under the home to the outside before it enters the building. Sealing cracks in foundation walls and floors and around pipes and drains can also reduce radon entry into the home.

Carbon Monoxide – Carbon monoxide is another toxic gas for which precautions should be taken when finishing a basement. Appliances like furnaces or water heaters that burn fuel such as wood, oil or gas can be sources of carbon monoxide. Faulty or improper ventilation accounts for most cases of carbon monoxide poisoning. Before finishing a basement have a certified HVAC contractor ensure adequate ventilation systems are in place. Combustion appliances need a source of oxygen (to prevent downdrafts). Annual inspection and maintenance of combustion appliances is recommended to ensure they are operating properly. Homeowners should also check exhaust vents after a snowstorm to ensure they are not blocked by snow. Lastly, always ensure a carbon monoxide detector is installed near the entrance of any bedroom. Carbon monoxide detectors can be hardwired, battery-operated or plugged in. Whatever model you go with make sure to follow manufacturer instructions for installation and testing.

Remember to look for my column in The News every Tuesday, I will be addressing a wide range of home-related construction and maintenance topics. I welcome readers to submit questions by sending me an email at or call me at 902-695-5919.


Gib Thompson is a Red Seal Carpenter and owner of MacGibbons Contracting Ltd. in Stellarton.