If you want to convert your unfinished or finished basement into a rental apartment, there are some requirements you need to follow to make sure it is a legal apartment. Following these legal requirements can help protect you from any potential liability. Here are some regulations you need to follow for basement HVAC and egress windows and doors when updating your basement to a rental unit.

HVAC System

According to the International Building Code, section 1204.1 any interior spaces intended for human occupancy needs to have an active or passive heating system to maintain a minimum indoor temperature of 68 degrees F at three feet above the floor. An air conditioner is not required for your basement apartment, but if you do install one, make sure it is properly maintained. Having an air conditioner in your basement apartment can be helpful to find and keep good renters, especially when you live in a warmer climate.

Mike Rupert with the Department of Consumer and Regulatory Affairs suggests as a landlord you should install a HVAC system for your basement apartment to meet the minimum requirements of heating and cooling. This includes a minimum heating temperature of 65 degrees F at night and 68 degrees F during the day. Then, the air conditioner should maintain the basement's interior at 15 degrees F cooler than the temperature outside. You or a company you hire, such as Elite Heating, Cooling and Plumbing, can install a window-mounted air conditioner or a ductless air conditioner on the interior wall of the basement unit, or add on to an existing central air conditioning system.

As you are converting your basement apartment, you are required to heat the space, but it is not required for you to install a separate heating system for the basement. For example, if your upstairs is set up on a heating furnace with forced air venting, or an oil heat system, you can (but don't need to) add the basement apartment onto the existing heating systems. 

The Department of Housing and Urban Development recommends to install a heating system in the basement as long as it is not an unvented room heater that burns kerosene, gas, or oil. Electric heaters are okay in a basement apartment. You can install an approved basement heating in each room of your basement apartment, such as baseboard heating. A separate heating system allows your basement tenants to set their temperature for their needs.

Egress Windows and Doors

For a legal basement apartment, you do not need to provide a separate basement exterior exit door for your tenant. You can share a common entrance to the home with your tenant, with separate entrances to each of your own units. But, the basement apartment needs to have appropriate-size windows to provide access for your tenant to escape in the case of a fire in the home. This includes window access in any basement rooms used for eating, sleeping, cooking, and living, including offices, recreation rooms, bedrooms, and home theaters.

To make it possible for your tenant to use a window as an exit if there is a fire, the window needs to have the required opening space. Each window needs a minimum height opening of 24 inches and a minimum width opening of 20 inches. The opening of the window needs to be at least five point seven square feet. The window sill cannot be higher than 44 inches from the floor of your basement apartment. 

If a window has an outside window well, the floor of the window well needs to be at least nine square feet in size. The window well cannot be less than 36 inches of horizontal projection and 36 inches in length. Make sure you provide a ladder inside the window well if it is more than 44 inches deep.

Use this information to help you make your basement into an apartment. Always check with your local building inspector office to verify any specific area requirements for a legal basement apartment.