Common Issues That Cause Basement Ceilings to Fail Inspection

When looking to add a secondary suite to a home, or even just an additional bedroom, the basement is a great location to do so! But there are a few regulations that must be followed. One area that often causes a basement to fail inspection is ceiling height. There are a few different reasons as to why basement ceilings can fail inspection. These issues are all very common, and most of them have a few possible solutions.  The good news is that most only become relevant when you're planning a renovation, and that's exactly when they can be addressed. 

At House of Three, we are happy to offer custom design plans that will better suit your basement needs!

Existing Build is Too Short

Many aging homes are actually too short and do not meet the ceiling height requirements for a basement. If you leave a basement as is, without any plans for construction, and if it passed inspection in the past, low ceiling heights are not an issue. As soon as you plan to do construction, such as add a bedroom, or a secondary suite, you must meet all current building code requirements.

Under the current Ontario Building Code, the ceiling height requirements are 6’-10 11/16” (2100 mm) over 75% of the basement area. If beams and ducts are present, clearance can be reduced to 6’-4 ¾” (1950 mm). In the case of secondary suites only, the clear height under beams and ducting may be further reduced to 6’-0 13/16” (1850 mm).

If you are interested in increasing the height of your existing basement, there are a few different things you can do. You can check and see if there is any free space above the ceiling, as sometimes people will install a dropped ceiling and there may be a significant gap to the underside of the floor joists. Alternatively, if only the ductwork is creating an issue, removing the furnace and reinstalling electric heat, whether baseboards or mini-splits, may be best.

Two less common options can increase the height structurally.  This can be done by extending further down into the ground, referred to as underpinning, and reconfiguring your existing foundation and concrete slab, or by “lifting” the house to add an additional row(s) of concrete block(s) to the existing foundation.  Either option can only be done with the guidance of an engineer. These options we do not often see as they are both extremely costly and would be best to do only if it significantly increases the overall value of the house.  Often it would be more beneficial to add a second floor addition or convert a garage to living space instead.

Beams or Bulkheads for Duct Work

Sometimes the ceiling can look low due to beams or bulkheads that are used to cover the ductwork. There are some cases where you can lift the support beams to be flush with the floor joists, to give you a little extra headroom in your basement. There are requirements for allocated space between ductwork and combustible material, such as wood. This height can vary from 1” to 5 ⅞” (25 mm to 150 mm) depending on the location of the duct. 

Improperly Installed Fire Separation

According to the Ontario Building Code, fire prevention and separation is mandatory between units and floors when constructing a secondary suite. Removing the basement ceiling and having the floor joists exposed to increase ceiling height is not permitted as exposed beams and wooden joists can burn quickly and collapse. Installing a closed off fire-resistant material, like fire rated drywall to create a fire separation is required. Fire resistant caulking should be installed around duct, pipe, and electrical work where they meet the fire separations. Smoke and carbon monoxide alarms must also be installed.

Closed-Up Ceiling Cavities Prior to Electrical Sign-Off

Like with any other portion of a building project, it is mandatory that you do not close up any cavities that contain electrical wiring. They must be inspected by an individual from the Electrical Safety Authority (ESA). This is to ensure that all electrical work was completed properly. Electrical work if done incorrectly can pose a significant fire risk.

Low basement ceilings only become an issue once you plan to renovate, and when they do, there are almost always options. The key is identifying these issues at the design stage, before an inspector does. 

Here at House of Three, we have a lot of experience converting basement spaces into legal units! We're happy to help you navigate the best renovation options for your space. You can book a free consultation with us to learn more about how we can help you.