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Deck & porch stair construction guidelines:
This article series explains critical safe-construction details for decks and porches, including avoiding deck or porch collapse and unsafe deck stairs and railings. Part 1 of deck stair building (below) outlines the basic codes & specifications for deck or porch stair construction. Part 2 of this article provides step by step details for laying out and cutting the stair stringer, attaching the stair stringers to the deck or porch, cutting and installing stair treads & risers.
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You may require stairs to get from the yard to the deck, from the deck into the house, from one deck level to another.
When they are needed, stairs can also add a welcoming, visually appealing element to a well-designed deck. But as we warn below at Warnings about Unsafe Deck & Porch Stairs by their very nature, stairs can be dangerous, and they are a primary site of household accidents.
Deck stairs may not have the glamour and character of a fine interior stairway but they do pose the same risks and require the same level of care regarding safety, m This article series provides the basic information you need to design and build attractive, functional, and safe stairs for your deck.
Our photo at above left shows a stair stringer and construction design that tells us the builder may have had trouble figuring out just how to attach and support these steps.
My dad called this "jackleg" construction. Lots of little parts, nails, wobbles, and stairs that slowly settle and rot into the dirt. This is not a great example of stairbuilding.
This deck access stair that may be unsafe due to its age, connections to the deck structure, and the absence of guardrails and handrails. Also this structure is in a shaded area exposed to slippery algae growth on the step and deck surfaces.
More about algae and other slippery step and walk surfaces is
at SLIPPERY STAIRS, WALKS
Ramps such as the access ramp shown at left can make your deck even more accessible, but their construction can vary because of local code differences and the variations from deck to deck.
Before designing your own, be sure to consult your local building department.
We discuss the construction and safety requirements for access ramps separately at RAMPS, ACCESS
Ramps also require guardrails and handrailings (the guardrail and handrails on the ramp shown at left are not code compliant).
The stair at below left was tall and wobbly and received this unique reinforcement. Tall stairways are safer and more comfortable with an intermediate landing.
The need to add support at mid-span on this stair could have been avoided and the handrailings would have been more secure if the vertical railing post at mid span in the stair had been brought to ground level and secured to a pier.
See STAIR PLATFORMS & LANDINGS, ENTRY for details.
The stair at above right was built by the website author and had to cope with a sloped entry point at the lowest step and an interrupted railing to permit access from the uphill side of a drive.
Our complete guide to building codes for stairs and railings can be found
at CODES for STAIRS & RAILINGS and at Related Topics above you can see our complete list of detailed articles on stair and railing construction for decks, porches, as well as in other applications.
As parts of a house go, stairs are dangerous places because of the risk of tripping and falling. That is why their construction is so often tightly regulated. Specific requirements vary from place to place, however, so be sure to check your local code. Some building codes are more flexible for exterior stairs than for those inside the house; some are not.
The vertical distance from one stair tread to the next is called the rise. Codes usually specify a maximum rise of 8 inches or so, but a rise of 6 to 7 1/2 inches is generally more desirable. The rise must be consistent from one step to the next, with a differential of no more than 3/8 inch. [1/4" in some codes].
The tread depth (or run) is measured from the face of one riser to the face of the next (or from tread nosing to tread nosing). Codes may require a 9-inch minimum for the run, but 11 to 12 inches is better.
Within the measurements allowed by code, choose a rise and run that work well together. In general, steps with a shorter rise are more comfortable with a deeper run; those with a taller rise are better with a shorter run. A good rule of thumb is that the tread depth plus the rise should equal 17 to 17 1/2 inches.
Stairs are usually required to be at least 36 inches wide. Up to this width, you should be able to use only two stringers, while wider stairs will require an intermediary stringer. Regardless of code requirements, however, many builders always use at least three stringers for stairs between 30 and 48 inches in width. The middle stringer adds strength and stiffness to the stairs and requires a little extra work.
See details about stair risers
at STAIR RISER SPECIFICATIONS. A summary is just below
2008 NYS Stair Code: R3184.108.40.206 - Stair Riser height Requirements. The maximum riser height shall be 8 1/4 inches (209 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm.) (Courtesy Arlene Puentes).
Shown at left, worn stone stair steps at the Hacienda Jaral de Berrio, Mexico. These steps are a trip and fall hazard, increased by the absence of guard railings and handrails.
Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Stair tread depths shall be 11 inches (279 mm) minimum. The riser height shall be measured vertically between the leading edges of adjacent treads.
The greatest step riser height within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at right angle to the tread's leading edge.
The greatest stair tread depth within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm). Winder treads shall have a minimum tread depth of 11 inches (279 mm) measured at a right angle to the tread's leading edge at a point 12 inches (305 mm) from the side where the treads are narrower and a minimum tread depth of 10 inches (254 mm).
The greatest winder stair tread depth at the 12-inch (305 mm) walk line within any flight of stairs shall not exceed the smallest by more than 0.375 inch (9.5 mm).
Guardrails are used along horizontal walking surfaces like a deck or balcony. A guardrail is there to prevent someone from falling off of the walking surface. Guardrails along a deck will normally be higher than handrailings.
A handrailing is placed along stairs to assist someone climbing or descending the stairs and to help arrest a fall should the stair user trip. Guardrails are also required along stairways but most codes permit the same structure to serve both purposes.
At left our photo illustrates both guardrailings (red arrows) and the handrailing along the deck stairs. This stair handrailing is not correctly built: it uses a 2x6 on flat and is not graspable along the stairway. The same lumber atop the guardrails is perfectly OK.
Local building codes regarding deck railings (also called guardrails) range from extremely lenient to tightly restrictive. If yours tends toward the former, do not take that as an excuse to cut corners. Railings perform an important function on decks by ensuring that they can be used safely by people of all ages and sizes.
A deck guardrailing and a deck stair handrail and guardrail may not be required in some code jurisdictions unless your deck surface is 30 inches or more above ground.
But 30 inches is a long way to fall, and more safety-conscious codes lower the requirement to 24 or even 15 inches.
Other codes may refer to the number of steps rather than the height above ground - typically three steps - that is, three risers.
If you are concerned about the well-being of children who might use your deck, keep in mind that there is no reason why you cannot put a railing on any deck, no matter how close to the ground it is.
We recommend installation of guardrails and handrails on all outdoor structures at any height above ground level.
Our photo (left) illustrates construction of a large deck to be used as a performing stage at the SummerBlue Arts Camp, Two Harbors MN.
The original construction, installation and long term performance of this outdoor performing arts stage floor are described in a series of articles given at FOUNDATION DAMAGE by ICE LENSING.
Railings are often designed to withstand a force of 200 pounds pushing down on them or against them. Imagine the stress caused by someone sitting on or leaning against the railing, and you will understand the need for such considerations.
The minimum height of a railing is usually 36 inches, but some people prefer a higher railing. Maximum railing height is often limited by restrictions that limit the span of 2 x 2 balusters to 34 inches, but adding a middle rail will allow you to use longer balusters and thus create a higher railing.
At left the photo shows a high deck that has no access stairs from the ground.
The deck is entered only from the second floor of this home. At the time of the photo the deck also had no guardrails. Happily guardrailings were later added by the property owner.
Spacing between all components of the railing should not be large enough to allow a 4-inch sphere to pass through (some codes say 6 inches).
The 4-inch limitation is meant to eliminate the chance of a child’s head getting stuck and is well worth obeying.
Some codes stipulate the sizes of fasteners that can be used at different locations. The codes specify fasteners that will maintain the ability to withstand a 200-poundload.
In some jurisdictions you are not permitted to notch railing posts to fit against the outside of the deck perimeter structure (rim joist for example), although notched posts are often used. Since these post connections are loaded by someone sitting on or leaning against the railing, and you will understand the need for such considerations.
The minimum height of a railing is usually 36 inches, but some people prefer a higher rail¬ing. Maximum railing height is often limited by restrictions that limit the span of 2 x 2 balusters to 34 inches, but adding a middle rail will allow you to use longer balusters and thus create a higher railing.
In the photo at left, my friend Paul Galow is standing on a deck he's built with no railings - happily he later added them.
Spacing between all components of the railing should not be large enough to allow a 4-inch sphere to pass through (some codes say 6 inches). The 4-inch limitation is meant to eliminate the chance of a child’s head getting stuck and is well worth obeying.
Some codes stipulate the sizes of fasteners that can be used at different locations. Typically codes specify fasteners that the rail and fasteners must withstand a 200-pound load. In some jurisdictions you are not permitted to notch railing posts to fit against the outside joists.
See CONNECTORS, FASTENERS, TIES
Deck railings usually rely upon vertical members, and for good reason. If you build a railing with horizontal members (such as in the illustration at right), which is perfectly legal in many areas, it is almost inevitable that children will want to start climbing the railing. This condition is potentially less safe.
See DECK & PORCH GUARDRAILINGS
Our photo (above left) illustrates a deck that really needs a railing. Even the builder (shown) can easily forget where that edge is, take one more step backwards, and ... boom.
Watch out: as we report at TABLES of ACCIDENT FREQUENCY by TYPE more people are hurt and lose work time due to stair falls than just about any other hazard. You want to make your deck porch stairs not only code-compliant, but as safe as possible.
At SLIPS, TRIPS & FALLS, EXTERIOR STAIRS we catalog a litany of stupid tricks that assure people are eventually going to fall down an exterior stair. We describe typical hazards such as slippery algae, snow, ice on steps, uneven or damaged treads or risers on stairways, or loose flimsy stair railings or deck guardrails.
Adding injury to the insult of unsafe stairs is an improperly constructed guardrail or more often, an improperly constructed handrailing along an exterior deck or porch stair.
When a person is falling they instinctively reach out to grasp a nearby railing to try to arrest the fall. A non-graspable or otherwise improper railing denies the person that help, surely aggravating the fall and perhaps injury that may result.
Continue reading at DECK STAIR BUILDING DETAILS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see DECK & PORCH CONSTRUCTION - home
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