Attic conversions are an affordable way to add livable space to your current house, but consider these regulations, requirements, and considerations first.

With the expensive nature of home additions, many homeowners look for creative ways to increase their living space within the existing footprint. We’ve discussed some of these ways in a previous article on Cost-Effective Alternatives to Home Additions. But in this article, we specifically explore attic conversions.

Like basement remodels, attic conversions come with a variety of restrictions and regulations. These considerations can make exploring this project type a little daunting. But if you can clear these hurdles, attic conversions just might be the best way to add more square footage of livable space without spending a lot of money.

Keep reading as we look at some of the nuances of attic conversions so you can better decide if this is the right project type for you. In this article we’ll cover:

• Codes and regulations
• Structural considerations
• Design considerations

Codes and Regulations

Space Regulations

The first code requirement we’ll look at is the minimum space requirement.

To satisfy building codes, you need to have enough space in your planned attic conversion to meet the following regulations:

• 70 square feet or more of floor space.
• At least 7 feet in any direction. (This would translate to a bare minimum of 7′ x 10′.)
• At least half of the floor space has a ceiling height of 7 ft. or more.

The purpose of these requirements is to avoid strangely-configured spaces. For example, a person might try to meet the 70 sq. ft. requirement by having a room that is 2′ x 35′. While impractical, without defining these minimum space regulations in the code, people might try to create these kinds of spaces which makes them difficult to access in case of an emergency.

If you have trusses, it’s hard to get the clear livable space you need. And in this case, it’s probably better to look for other areas in your house to expand, not the attic.

If you have rafters, on the other hand, you have a better chance of creating livable space in your attic. So keep reading.

Suitable Access

Your attic may presently have a fixed ladder, a pull-down ladder, or no ladder at all. What your attic probably doesn’t have is a set of code-compliant stairs. To convert your attic to living space, you cannot provide access via a ladder. If you’re lucky enough to already have a set of stairs to the attic, you may be able to use without triggering a code-compliance review if your attic design doesn’t alter them. It’s best to check with building codes and local code officials to be sure.

If your attic doesn’t have a set of stairs, your design will require one.
The staircase must:

• Provide a minimum of 6’8″ of headroom the entire walking length of the stairs.
• Be at least 36″ wide.
• Have treads of at least 9″ deep.
• Have risers that are no more than 8 1/4″ high.

There may be structural implications of adding a stair, so it’s always good to consult an engineer.

Two Means of Egress

Attics are the worst place to be in the event of a fire because heat and fire rise (rapidly!). Since any staircase to the attic can act as a chimney for the fire to quickly spread, it’s necessary to have a secondary point of egress or exit.
In most codes, this means an operable (not fixed) window to the outside or patio door.

Structural Requirements

Suitable floor framing

Your attic floor framing was probably built with dead loads in mind. The framing was meant to support the dead load of the ceiling below and perhaps some boxes or suitcases. It also was built to provide lateral support to prevent the sloped roof rafters from spreading outward and collapsing.

In most cases, though, the joists won’t be able to support the new (higher) live loads of occupying that space. The joists may not even be covered with floor sheathing to walk on. You may open up your attic and find bare joists with fiberglass or cellulose insulation between the joists and nothing more.

An engineer will be able to tell you if your joists can support the new loads. And if not, the fix is usually to double up the framing before laying down your sub flooring.

Openings for stairs

As we mentioned above, if your current house doesn’t have stair access to the attic, you’ll need to incorporate this into your design.

Adding a stair can be challenging because it requires cutting existing ceiling joists to create the opening. These ceiling joists are doing a lot of work to transfer loads from the roof to the walls and from your future attic floor to the walls. An engineer will be able to advise you on the framing but in most cases, it requires adding more framing members around the opening to transfer the loads to the remaining ceiling joists.

It’s also usually easier to frame the new opening if your stair runs parallel to the direction of the joists. That way you’re only cutting 2-3 joists. If your design calls for a stair running perpendicular to the joists, you’re looking at a larger beam to support more joist ends.

Roof framing alterations

If you want to add more natural daylight into your attic space, you’ll most likely need to cut openings into your existing roof. Skylights, dormers, and large windows usually require additional roof framing around the openings to transfer loads to the surrounding roof rafters. Again, an engineer can help you with the framing design but depending on the size of your openings, this could be achieved by sistering roof framing to the existing rafters.

Removing partition walls

In some cases, attic spaces have partition walls already constructed. If the attic is partially used for storage, partition walls may have been used to delineate the space.

Depending on your new attic design, you may want to remove these walls to take advantage of additional floor area beyond these walls.

But without expert advice, it’s hard to tell if these walls are supporting part of the roof framing above. So, before removing any walls, consult with an engineer to confirm the walls can be removed.

[1653 Residence by Studio Build. Photo by Bob Greenspan Photography.]

Design Considerations

Aside from code and structural implications of an attic conversion, there are also design considerations to think about.

Local building codes specify minimum room sizes and ceiling heights but beyond that minimum, it’s up to you and your designer to determine the room boundaries and functions of the space.

Let the existing architecture dictate the layout

Existing architectural elements will start to define the layout of your space. Characteristic of many attic conversions is the strategy to locate storage spaces along the exterior, saving the middle interior space for circulation since it has the higher ceiling.

In many cases, you’ll see bookshelves, clothes storage, and lower shelves along knee walls at the perimeter. Because many attic spaces have sloped roofs, it’s important to consider how these roof slopes impact your design.

If there are existing openings in the floor for stairs or ladder access, the easiest and most cost-effective design solution will utilize these existing openings for stair access. It’s usually more cost-effective to use an existing stair opening and stair than it is to cut a new opening for a new stair somewhere else.

Also, some houses have chimneys, mechanical ducts, or plumbing pipes that may dictate the layout of the new design of the space. If you’re adding a new bathroom, you may want to locate it near the existing plumbing walls downstairs. If there is an existing large masonry chimney that is to remain, you’ll want to work around it for the new space configuration.

[Clayton Street Remodel by Mork Ulnes Architecture. Photography by Bruce Damonte Photography.]

Let there be light

Your existing attic space was probably never conceived as being livable space when it was constructed. And as such, there was no consideration to daylight or views either.

If you intend to make your attic space a welcoming habitable space, you may want to consider skylights, dormers with windows, or other wall openings to let light and air into the space (perhaps even a door and exterior roof deck). Nothing improves a claustrophobic attic space like natural daylight.

One idea is to consider adding a series smaller skylights between the roof rafters. Sized to fit between the rafters, these skylights provide daylight without altering the existing roof framing.

Roof Insulation and ventilation

Attic spaces are notorious for being hot and stuffy in the summer and cold in the winter.

Because heat rises and it has nowhere to go once it reaches the attic, attic spaces should have exhaust fans and/or other mechanical heating/cooling systems if you intend to make them livable.

Depending on how your house was built, you may have batt insulation between your ceiling joists or above between rafters along the roof slope.

In either case, it’s important to maintain continuous insulation along surfaces defining your livable spaces, including your new attic conversion. This may mean that you have to remove the insulation from between the ceiling joints and add it to the roof rafters above.

In theory, this sounds manageable, but consider that moving insulation to a new location will most likely trigger needing to meet newer energy codes. In many cases, the depth of the rafters isn’t deep enough for the newly required insulation thickness. You’d either need to increase the depth of the rafters by adding deeper rafters to the roof framing or switch to a more expensive type of roof insulation that achieves the same insulation value in a smaller depth.

In addition to all this, you’ll still need to ensure the roof is vented. Check with your local codes, building officials, and your designer or architect about insulation requirements and venting before moving forward with your project.

To summarize what we just covered, here are the key points to creating an attic conversion:

1. Ensure your attic meets the minimum space requirements. (This is best done with rafter roof framing, not trusses.)
2. Provide code-compliant stair access to the attic. (Confirm new openings in joist framing with an engineer.)
3. Provide a secondary means of egress.
4. Confirm the floor framing can support live loads.
5. Use existing architectural elements to guide you in the space layout.
6. Provide proper insulation and HVAC systems.
   

Feature Image Photo credit: Jesus Rodriguez via Flickr.