attic renovation

Attic Master Suite Addition by Airoom in Long Grove

Attic renovations can be much more than meets the eye. To many, the attic is an unclaimed portion of their home ready to be converted to bedrooms, baths, or even rec rooms. While it may appear that this transformation would involve no more than some flooring, insulation and drywall, attic remodels are fairly complex.  As discussed below, there are many factors that can affect the headroom of the new living space including new floor systems, insulation and rafter size.  While a professional remodeler can explore your attic’s potential, a good rule of thumb is if the existing distance between your attic floor and ridge (peak) is less than 8’6” increasing the roof height will most likely be required. The minimum finished ceiling height of living space varies from town to town but often falls between 6’ 8” and 7’6”.  Further explanation of those factors that can limit the headroom of your finished attic and other code considerations are explored below.

attic floor joist

1. KNOW THE DIFFERENCE BETWEEN YOUR CEILING AND FLOOR JOISTS.
More times than not, the floor structure of an existing attic is actually a ceiling joist.  Typically, ceiling joists are 2×6 or 2×8. They are designed to carry only the weight of the drywall (or plaster depending on the age of your home). Once we look to make the attic livable space, the existing ceiling joists usually will not meet the structural requirement for a floor. There are many factors that will determine what kind of new flooring system will best fit your home’s existing structure, while making your floor code compliant. While contacting a qualified design professional would be the best first step in determining the necessary floor structure, a variety of approaches are discussed below.

attic floor system

2. Two ways to create a new floor system.
Sistering, installing new larger joists next to the existing ones, is one way to bring your attic floor up to code.  Positioning the new joist adjacent to the existing preserves precious ceiling, but it does come with some potential complications. Often, existing joist bays are filled with electrical and heating ducts that will need to be relocated.

Engineered Floor Joists provide increased structural reliability and are not susceptible to crowning, bowing, or shrinkage that is sometimes associated with dimensional lumber (2x10s, 2x12s etc). With the improved performance and reliability, engineered joists sit atop your existing ceiling joist and often span from one outside wall to the other. This typically allows existing mechanicals to remain and does not put any increased burden on existing load bearing walls or basement beams.  An added benefit to the engineered joist is that it allows for complete flexibility in bath and mechanical design as the joist can be engineered to allow for new plumbing and mechanical runs (no longer have to stack new baths directly over existing).

While each flooring system has advantages and disadvantages there are other factors that may play into which system is the best fit for your home.

structural floor system

3. Structural stair system needed.
Once a qualified builder determines the best approach to securely construct the attic floor, it is important to determine how you will access the new space.  In older homes, the attic stair is often narrow and steep which will no longer comply with today’s codes. In the event where the new attic floor requires increased structure, an existing attic stair will no longer land at the floor level as the new joist will be taller than the existing. In the majority of cases a new stair and structural opening will be required.  Determining the stair’s pitch, structure and location is fairly complex, so consulting a qualified design build firm is paramount.

attic insulation

4. Proper insulation is key to controlling varying temperatures.
How does a space that reaches 150 degrees in the summer and freezing temperatures in the winter transform to your new living space? Insulation, insulation, insulation. Over the past several years there has been an increased focus on making insulation codes more stringent. Current insulation code requires R-49 insulation in the ceiling.  When using fiberglass insulation (the pink stuff) the attic roof rafter will need to be at least 16” deep. In an older home, a typical roof rafter can range between 2×4’s to 2×8’s. In order to create a deeper cavity for the insulation it will be necessary to attach wood framing to the existing rafters through a process called “furring”.  In addition to some of the structural considerations mentioned earlier furring can further reduce your existing attics head room.  Spray insulation, while costly, can achieve increased R values in smaller cavities and therefore can occasionally avoid the need for furring.

attic building restrictions

5. What are the building restrictions in your town?
Every municipality has a set of guidelines that regulates the shape, size and position of your home. It is essential to check with your municipality to determine that the newly habitable area will fall within the established zoning code. Beyond potentially maxing out the allowable square footage (often called FAR  or Floor Area Ratio) in some cities, including Chicago, if the attic is a third floor two sets of stairs is often required.

attic hvac

6. Can your existing mechanical systems handle the added space?
As mentioned earlier, attic space is susceptible to extreme temperatures. Existing HVAC (Heating, Ventilation and Air Conditioning), systems are sized for the existing home; therefore tying the new space into the existing system is often not possible.  While a new HVAC system can be an unanticipated cost, there are added benefits including simplified duct runs and the ability to independently control the temperature.  Beyond HVAC, it is also important to determine that your home’s existing plumbing and electrical can withstand the additional outlets, lighting, and bath fixtures.

attic windows

7. Don’t forget to let the light in.
Every room in a home, whether a bedroom or living room, has a stated light and ventilation requirement. The required amount of light and ventilation varies by the room type (for example, bedrooms require more than dining rooms). Light and vent requirements are met by adjusting the amount and size of the windows. Often, the amount of exterior wall space in an existing attic is scarce.  Therefore, locating windows and determining room layout becomes a delicate balance. Additionally, it is important to research your municipality’s egress requirements as certain rooms such as bedrooms will require windows to meet certain minimum clearances.


If you would like to learn more about finishing your attic space and how it could work in your home, contact Airoom to schedule a complimentary designer consultation. Or browse our remodeling galleries.