The IRC limit gives a 2r+R of 25 ½”. Staircase code states that stairs must be 3 feet wide or wider. Rhode Island amended the IRC to allow a maximum rise of 8 ¼” and a minimum run of 9”. 2r+R = 25 1/2" (within range) Anyone walking up or down the stairs should have plenty of clear headroom without having to duck down. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). If stairs are more than 1000mm wide it must have a handrail on both sides. The greatest tread depth within a flight of stairs cannot be more than 3/8 inch larger than the smallest tread depth. 2r+R = 25 1/4"" (almost perfect) run R = 10" Just be aware that some building codes specify a maximum number of risers from landing to landing, and that shorter risers results in more treads and greater tread depth, extending the overall run of the stairs. At any point on the staircase, a user should have a full 6 feet, 8 inches minimum vertical distance between the top of the stair tread and the bottom of the ceiling. Trusted, in-depth guidance from the pros for framing a durable, code-compliant house. Staircase risers should be adequately deep to allow a majority of your foot to have enough room to rest on the stair. 2r+R = 25" (perfect) number of risers : modify the Maximum Riser Height stair type property. What about something like this? Further, the tread measurement of every tread in a stairway should be as close as possible to identical. You have probably had the experience of using stairs, often in an institutional setting, that felt ridiculously shallow, possibly even requiring stutter steps, or inducing the strong desire to take two steps at once. Framing Project Guide. Except as permitted for dwelling units and by Sentence 3.4.7.5. Per the 2018 International Residential Code the maximum stair riser height is 8-1/4″. Stair tread depth is more of an issue for descending, rather than ascending, stairs. Stairs that are too narrow are a hazard in many ways. (1) for fire escapes, steps for stairs … Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. To overcome this you can simply add an extra handrail, newel and spindles to divide the staircase. Rectangular tread depths shall be 11 inches (279 mm) minimum measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. This distance must be at least 36 inches and does not include handrails. The greatest riser height within a flight of stairs cannot exceed the smallest by more than 3/8 inch. The following staircase code requirements pertain to straight-run stairs. The going must be betwee… Maximum stair step riser height (<= 7.75") or in some codes <=8" Minimum stair step riser height: >= 4" Step riser height uniformity <= 3/8" variation between successive step surfaces, or … I usually end up having to squeeze the stair for one reason or another, but on the rare occasions I can include a 7-11 stair, it ends up being very comfortable. Every staircase should have a landing at the top and bottom. 1.2. These rules are aimed at making staircases as safe as possible, so they should never be ignored or bypassed. Molasseskat commented with a good idea; here is a graph that shows what I consider the “sweet spot” for stair design. Stair Riser Height Measurement. That would give an r+R of 18”, right on the money for stride length. Run x rise = (70 to 75), Any idea how to add it to the graphic representation? 1917.120(b)(2) Stair landings shall be at least 20 inches (50.8 cm) in depth. (1) Staircase riser height translates to the distance you move your foot either up or down from one step to an adjacent step. 2r+R would be 24 ½”, pretty good, but r+R is only 16 ½”, not enough, and the stair would feel diminutive. The Stair layout remains the same, including the Actual Tread Depth, and Total Actual Number of Risers values. The result was a disastrously uncomfortable stair, with treads too short for adult feet. Knowing what kind of headroom or winder you can use is very, very important. How about a minimum run of 9 ½” but keep the riser down at 7”? It also happens to be the dimension of one of the cuts on each of the actual stair stringers–the framing members that hold up the stair treads. I included icons for each of the stairs described in this article: Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers. The minimum riser height shall be 4 inches. 9.8.4.4. The riser height shall be measured vertically between the leading edges of adjacent treads. The minimum tread depth is 10 inches, with a 1-inch nosing. The treads and landings of all straight-run staircases should have an artificial light source capable of lighting the treads and landings to no less than 11 lux (approximately 1-foot candle). Here’s a good example of a stair I don’t think anyone would mistake for being comfortable. Riser height shall be from 6 to 7.5 inches (15.24 to 19.05 cm), stair width a minimum of 22 inches (55.88 cm) between vertical barriers, tread depth a minimum of 12±2 inches (30.48±5.08 cm), and tread nosing shall be straight leading edges. For more information, see Section 1011 of the 2015 International Building Code for a more in-depth look at commercial stair requirements. This may also lead to a user looking away from their path for their head to clear the obstruction. You should measure riser heights vertically, between the leading edges of two consecutive steps. 27.2 TREADS AND RISERS On any given flight of stairs, all steps shall ha ve uniform riser heights and unif orm tread w idths. Nosings must project at least 3/4 inch and no more than 1 1/4 inches beyond the riser below. Twice the rise plus the run (2r+R) should be within an inch of 25”. → stairs will be comfortable, Shallow stair example: Although the rise itself wasn’t terrible, something about using it felt very cramped, and I set out to find what went into a safe, comfortable stair. If they are not circular the perimeter of the sides must total 4 to 6 ¼ inches with a maximum cross-section dimension of 2 … Not all staircase measurements are universally the same in all parts of the country, though. The problem is when you have a small space in your ground floor like 40 square meters floor area placing your stair with that measurement (7" - 11") is really a challenge. Handrail grips may be circular, 1 ¼ to 2 inches in diameter. If the stairs have open risers, the open space between the steps cannot be large enough to allow a 4-inch sphere to pass through. The minimum depth, measured in the direction of travel, is 36 inches. :). But 2r+R is only 22”, pretty far from 25”, and results in the stairs feeling like you need to take them two at a time, or that you are shuffling up them one step at a time. What if situation allowed for keeping the maximum rise of 8 ¼” and we expanded the run to 10 1/2”? 1009.7.2 Riser height and tread depth. Most straight stairs have a typical riser height between 7” – 7.5” whereas spiral stair riser height has a maximum riser height of 9.5”. My ideal stair has a 7” rise and an 11” run. This should be no more than 7 3/4 inches. Risers – the vertical faces of each step – should be 6” whenever possible under typical conditions, as this dimension provides the most ergonomic function. In order to eliminate tripping hazards, the dimension of a Riser should always be a minimum of 4” and a maximum of 7”. IBC 1011.14.2 requires that alternating tread devices have a maximum riser height of 9 1/2" (241mm). I relied on the 18” rule for several years, until I met another carpenter who insisted that a better measure was that twice the rise plus (2r+R) the run should be 25 inches. A step tread is the flat, horizontal surface that you walk on. The maximum of 18 risers in a flight. Table 9.8.4.1. Lee has over two decades of hands-on experience remodeling, fixing, and improving homes, and has been providing home improvement advice for over 12 years. On the first stairs I built, I sized them for a 1×8 riser and a 2×8 tread. I call it a lazy stair, because it seems to take no effort to use (but you still feel like you’re getting somewhere). Rise, Run and Tread Depth for Rectangular Treads. In any case, the local code is what you must follow to pass inspections. There should not be any single steps. Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. Keep in mind the straight stair riser height and spiral stair risers height is different. run R = 4" After trying to decide which rule really was better, I settled on the idea of using both. The riser shall be measured vertically between leading edges of the adjacent treads. run R = 9 1/4" The IRC (International Residential Code) calls for a maximum rise (“r”) of 7 ¾” and a minimum run (“R”) of at least 10”. The “Run,” however, seems to cause some confusion. Yes. In your case, if you'd like a shallower but still-comfortable stair, you'll need to add one or more risers to what is currently designed, then adjust the tread depth (aka Run), staying within the yellow zone on the new graph at the end of the article. The maximum riser height is 7 ¾ inches; all risers must be within 3/8” of each other. Buildings codes have been created to control the minimum and maximum measurements of risers and treads. Stairs with more than 36 risers in consecutive flights should have at least one change in direction between flights. By using The Spruce, you accept our, Staircase Riser Height: 7 3/4 Inches, Maximum, Staircase Tread (Run) Depth: 10 to 11 Inches, Minimum, Staircase Headroom: 6 Feet, 8 Inches, Minimum, Deck Code Guidelines for Guardrails and Stairway Railings, 17 Staircase Ideas That Stop Us In Our Tracks. If the stairs have nosings, you measure from the leading edge of the nosing to the edge of the next step’s nosing. By "squeeze the stair," I mean that on my jobs space is usually at a premium, so we cheat the stair to be steeper than ideal, often with code-minimum 10" Run and approaching the code-maximum 7 3/4" Rise. Critical measurements such as standard stairway width, riser height, and tread depth are not a matter of guesswork when you are remodeling or building a home. A not-too-extreme example of that would be something like a 4” rise and a 14” run. It might be best described using a graph of run vs. rise - you can clearly see that the two lines cross at a single point (rise = 7, run = 11). With an r+R of 17 ¼” and a 2r+R of 25 ½”, both numbers are close enough to the ideal to be comfortable for most people. Forming Part of Sentences 9.8.4.1. run R = 14" OSHA 1910.25(d)(2) requires spiral stairs to have h ave a maximum riser height of 9.5 inches (24 cm). Or if your design allows, you could have 18 risers at 6.56" with a Run of 12". Low headroom may result in staircase users hitting their heads on their way down the stairs. Narrow stairs make it more difficult to carry items up and down the stairs. Mike was able to eliminate a tread and riser and use the headroom gained to create more floor space and an interesting nook in one of the bedrooms, using a rise of 8” and a run of 9 ¼”, for r+R of 17 ¼” and 2r+R of 25 ¼”, well within the comfort zone. 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