Renovating a full-height basement can be a relatively easy, cost-effective way to add living space to your home.
But is your basement a good candidate for a renovation?
If your basement isn't high, dry and sound, you should correct these problems first.
If you're planning a basement renovation, inspect your basement and ask these questions:
- Do you stoop to avoid bumping your head on a beam or duct?
- Are there intermittent or permanent traces of moisture or mould on the floor or walls?
- Is there a persistent musty odour in clothing and other objects stored in your basement?
- Are there cracks as wide as a pencil, or that appear to widen or shrink, in the walls or floor?
If the answer to any of these questions is "yes," you should include the costs of fixing these problems in your renovation budget.
Dampness or leaks in walls or floor must be corrected, because moisture problems can ruin even the most expensive renovation.
If you intend to live in your basement, ensure there is a proper drain with a trap situated at the low point of the floor. The trap must be kept full of water to function properly, so don't forget to top it up periodically.
If there's no sanitary sewer in your area, you may need to install a sump pump in a pit near the lowest point in the basement floor. Cap the pit to stop foreign objects falling in that could damage the pump.
The pump should discharge to a dry well or a spot above ground where the water won't leak back into the basement.
You also should consider installing a backwater valve to prevent an overloaded sewer line backing up into your basement. It's an expensive proposition, but it can protect your basement reno from serious damage if sewers back up during heavy rains, for example.
The device should be located to prevent sewage from coming through basement fixtures, such as sinks, toilets, showers and laundry tubs.
You must obtain a building permit if you intend to alter the structure of your house, increase the size of windows or exterior doors, or change the occupancy -- for instance, by adding a self-contained apartment. A permit ensures the changes meet minimum health and safety standards.
To make a good living space, a basement should be high enough to permit ceiling fixtures or fans with space beneath for someone 1.8 metres (six feet) tall.
Most municipalities require 2.1 m (6.8 ft.) from finished floor to ceiling before they'll issue a building permit. That's also the minimum height most electrical codes require for a ceiling light.
Some jurisdictions permit limited obstructions, such as beams or heating duct bulkheads, within this space. Ask your local building official what minimum heights are required.
Canada Mortgage and Housing Corp. offers these tips for preparing foundation walls and space:
To prevent heat loss, most jurisdictions require exterior basement walls to be insulated for most of their height.
While builders usually insulate the wall's inside face and cover it with drywall, it's better to put water-resistant insulation on the exterior face, where it can keep the foundation warm.
If the wall is warm, the dew point -- the point at which water vapour in the air condenses into water -- will be reached on the exterior of the foundation, where condensation will do no damage.
If you insulate the foundation on the inside, expect some moisture to condense on the inside foundation wall. Putting a moisture barrier, like vapour-permeable building paper, on the inside face of the foundation from grade level to floor will stop this moisture from wetting the insulation.
The top of the wall and the space between the joists should be insulated, because most basement heat loss occurs here.
Cover the warm face of the insulation with a polyethylene vapour retarder and seal with caulking where the polyethylene meets the floor, walls and ceiling, and at all laps to keep moisture from getting into the wall. Consult the building code for your jurisdiction for basement insulation requirements.
Dampness and cold can enter a basement floor from the ground beneath. Building codes require occupied basements in new homes to have a moisture barrier, such as polyethylene, under the floor.
If you have an older house with no under-floor moisture barrier, consider placing polyethylene over the existing floor before installing finished flooring. If space and headroom permit, you might also install water-resistant insulation, such as extruded polystyrene, under the finished flooring for a warmer floor.
Occupants of all parts of the house, including a finished basement, should have a safe exit to the outside. Basement windows, doors and exit routes must comply with local building and fire codes.
The National Building Code of Canada (NBCC) regulates the size of components that make up the exit path:
- Exit doors must be at least 810 mm (32 in.) wide and 2,030 mm (80 in.) high
- Corridors must be at least 900 mm (35 in.) wide
- Stairs must be at least 860 mm (34 in.) wide between wall faces and have at least 1,950 mm (77 in.) of headroom.
If a window serves as an escape route, it must be big enough, easily accessible from the living space, and provide safe access to grade level. You may have to replace or enlarge existing windows to meet these requirements.
Similarly, you may need a handrail and protective guard on the open side of a stairway.
And if you're converting an unfinished basement to living space, you may have to change the rise, run and tread depth of stairs to meet code.