Do Attic Stairs Need To Meet Building Code? (Read First!)

We’re doing a lot of work in the attic as part of our extension, so do our new attic stairs need to meet building code?

If you’re converting your attic into living space then both the attic itself and the stairs will need to meet building code. These cover the height and width of the attic stairway, the rise of the flight of stairs, and the rise and run of the individual stairs. 

Let’s dig down into this topic in greater detail, and discover whether attic stairs need to comply with building regulations in all circumstances, what those regulations are, and what the attic access code is…

Do Attic Stairs Need To Meet Building Code?

Do Attic Stairs Need To Be Building Code Compliant?

If you – or someone – is going to live up there, then yes. If you are planning a livable, legal, and marketable space, then everything will have to be code compliant, including the stairs. 

Building to code isn’t about counties and inspectors cashing in on additional paperwork. Sure, it can be a time-consuming, costly headache. But building codes are written and enforced so you and your family can be sure that your home has been built with the newest and safest construction practices.

For a livable attic space, here are the main items that will have to be in code compliance: floor space, floor strength, ceiling height, code-compliant stairs, emergency egress, wired smoke detectors, and arc fault protection breakers. 

The attic floor space must consist of at least 70 square feet of floor that is at least 7 feet wide and is at least 7 feet tall (aka the “Rule of 7”). In other words, if your ceilings slope down to 5 feet, you can’t include the square footage under the 5-foot ceiling. If part of your attic is only 4 feet wide, it won’t count either.

You may need a building expert to help you with floor strength. The floor strength measurement is a function of joist spacing, joist span, joist wood species, and joist depth. It’s a complicated measurement in pounds per square foot of the live load and the dead load of a floor.

The code rule for ceiling height states that the finished attic ceiling has to be at least 7.5 feet high for half (50%) or more of the floor space. 

No ladders or pull up stairs to your livable attic. Attic stairs must be finished and permanent. They need to be at least 36 inches wide. The stair ceiling should be at least 6 foot 8 inches high along the entire stairway.

The individual stair treads must be at least 10 inches deep. Stair risers should be at least 7.25 inches but no more than 7.75 inches tall. Finally, you will need at least one handrail.

Emergency egress is a way out of your attic besides down the stairs. A house on fire is always dangerous but attics are more dangerous because heat and fire rise. If the stairs are blocked by fire, then a wide window with an emergency ladder or another door to the outside is required by code. 

If your emergency egress is through a window, then the smallest opened size is 20 inches wide by 24 inches tall. The base of the emergency egress window must not be over 44 inches from the floor.

Wired smoke detectors, not individual ones, in your attic space are a must. The wired smoke detectors should have their own circuit. If you have a small attic, then one detector in the stairway and one in the living space should be enough.

Finally, the attic must be wired with arc fault protection. This is a common requirement for new home circuits.

Here’s a good video with stair codes, along with other livable attic codes.

What Are The Building Codes For Permanent Attic Stairs?

Building codes for permanent attic stairs are for the height and width of the stairway, the rise of the flight of stairs, and the rise and run of the individual stairs. 

The ceiling, or headroom clearance, along the entire length of the stairway should be a minimum of 6 feet 8 inches. This means you can measure from the surface of any stair up to the finished ceiling and it will be at least 6 feet 8 inches.

Stairway width should be 36 inches, measured along the stair from wall to wall. If you are going to install one handrail, then the minimum width measured between the handrails becomes 31.5 inches. If you need two handrails, then the smallest width becomes 27 inches, measured between the handrails.

A flight of stairs is defined as a continuous run of stairs. Code states that a flight of stairs shouldn’t rise vertically more than 12 feet 7 inches between landings. Starting at the bottom landing, measure the rise to the next landing. If you are over the maximum, then you’ll need another landing.

Then, the stairs themselves have code standards. The stair must rise no less than 7.25 inches but no more than 7.75 inches. Also, the difference between stair risers in a flight shouldn’t be more than 3/8 inch.

Finally, the depth of each stair tread shouldn’t be less than 10 inches, measured from nose to nose. And because our feet expect each tread to be the same depth, a tolerance of 3/8 inch is allowed between all the stairs in a flight.

This is a good reference article explaining stair-building codes.

What is Attic Access Code?

The attic access code is officially found in Section R807.1 of the 2018 International Residential Code (IRC), but be sure to check with your local building codes as well. The IRC code applies to attics that have at least 30 square feet and have more than 30 inches of clear headroom. 

The rules in the code apply to all buildings with combustible roofs and ceilings, which is true for most homes. For attics smaller or lower than the IRC standard, the code doesn’t apply.

Attics that meet the IRC size requirement, whether finished or not, should be accessible in case of emergencies. To meet code, if no one lives up there, they can have an attic hatch with a ladder, a pull down ladder, or a pull-down stair. If they are livable, they need a finished staircase. 

The attic access code states that all attics that meet the size requirements should have an opening measuring no less than 22 inches by 30 inches and the access must be located in a space that is accessible, like a hallway.

If you have an appliance such as a furnace, attic fan, or an air conditioner installed in your attic, then the code changes. A hatch is not good enough – you need some pull-down stairs, a pull-down ladder, or permanent stairs. Also, if you have an appliance in your attic, then the minimum access space changes to one large enough to get that appliance back down.

In addition, if you have an appliance installed in your attic, the code says you should have a strong, continuous, level pathway to it and some solid flooring around it. Here’s the code to check if you have an appliance in your attic: IRC Section M1305.1.3.

This article explains and references the various attic codes you should know about.

Attic stairs

How Wide Do Attic Stairs Need To Be?

As mentioned, attic stairs need to be 36 inches wide, measured along the stair. 

What Is The Standard Attic Opening Size?

The IRC attic access code states the smallest opening size has to be 22 inches by 30 inches. However, the average size of most attic openings is larger, at 22 inches by 54 inches.

Most attic openings are larger than code specifies because they have pull-down ladders installed. Also, builders make the opening large enough for the average-sized person to carry stuff like boxes up and down the ladder.

Do Pull Down Attic Stairs Need To Meet Building Code?

We always recommend meeting building codes. Be sure to read the IRC code and to check the safety code in your area, as they can be slightly different.

In many areas, local code specifies the use of fire-rated, pull-down attic ladders in new homes or remodels. These fire-rated ladders are fire resistant, and the insulated access hatches operate as a blaze block. Some fire-rated pull-down stairs come with gaskets that expand with heat so smoke is blocked from entering the attic.

Final Words

Our architect and construction foreman are doing a great job on our new extension, and at the time of writing, we’ve just received the structural plans for our roof and attic space.

We’re planning to make the attic a liveable area, so we’ll definitely be complying with all relevant building codes when we do the work on the attic stairs.

We’d also advise you to do the same – so it can’t come back and bite you later on! 🙂