Stair Dimensions 9.8.2.1. where the … The minimum widths stated above still apply. Width is calculated as clear, net, usable, unobstructed space. If you’re looking at a door on a set of plans rather than measuring the clear width of an existing door, the exact clear opening width can vary slightly depending on the hinges or pivots. Stair width: Landing Travel Top Distance 8 §1011.6 FIG 7 : Stair width: Landing Travel Bottom Distance §1011.6 FIG 7 : Stair width: Landing Door Swing Clearance §1011.5.7.1; §1011.6 FIG 7 : Stair Width ÷ 2: Landing Door Open Clearance §1011.5.7.1; §1011.6 FIG 7 : … Unlike residential stairs per the IRC, where the width is just a given measurement, commercial stair width per the IBC is based on capacity. We cannot have a stairway that is 44” wide and the other one is 46”. 2)Exit stairs serving a single dwelling unit shall have a width of not less than 860 mm. Note, the building is fully sprinklered so it is my understanding that under exception (2) the 48" minimum width between handrails required for a stair to be "accessible" per 1009.3 does not apply. In order to determine this the code refers us to Section 1005.1, but before we look at this section the code does say that the minimum width shall not be less than 44 inches. It shall be unlawful to alter a building or structure in a manner that will reduce the number of exits or the minimum width or required capacity of the means of egress to less than required by this code. 2. ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures. How do the codes aid in achievin… (C) The total cumulative occupant load assigned to a particular stair shall be that stair’s prorated share of the total occupant load, as stipulated in 7.2.2.2.1.2(D) and 7.2.2.2.1.2(E), calculated in proportion to the stair width. 11” deep treads. International Building Code Ships Ladder Requirements. Where stairways serve more than one story, only the occupant load of each story considered individually shall be used in calculating the required capacity of the stairways serving that story. When we consider the ideal classroom, we may think in terms of 15:1 or 20:1 student:teacher ratios.When we discuss the realities of District resources, we may see as much as 25:1 or 35:1.Applying the code requirements between these two scenarios requires analysis of the unique environment. Finally calculate the total exit capacity after discounting the largest exit (or exits in the case of ones that are By Sarah. occupants cannot access it due to a fire) the remaining stairway width(s) cannot be reduced to less than half the required combined width. Example: calculating multi-story stair width, Example: calculating single-story stair width. available width of egress components (doors, stairs, corridors, walkways, etc.). 1011.2 Width & Capacity The required capacity of stairways shall be determined as specified in Section 1005.1, but the minimum width shall be not less than 44 inches. What are the objectives? 1001.3.1 Maintenance of Exterior Stairs and Fire Escapes. Further requirements in Chapter 7 of NFPA 101 provide the details for calculating egress capacity of the space. Take the largest width that you calculate, and use it for the entire stairway system. Width is calculated as clear, net, usable, unobstructed space. What factor do I use to determine my “calculated width”? According to the International Building Code 2018, ship ladders cannot be used as a means of egress (with one exception.) A minimum 44″ wide in most cases (36″ wide areas served by less than 50 people) Railings & Guardrail. Stair widths are based on the use and occupancy loads of adjacent spaces and must be serviced with handrails on one or both sides depending on the stair width. To calculate the occupant load for an area without fixed seating, the code says to compute the area of the room or space at a rate of one occupant per unit of area using the occupant load factor found in Table 1004.1.2. Contact. Step 1 Walk along the egress path and determine the narrowest location in the route. Step 3 . Example calculation for occupancy figure Using the floor space factors the number of persons that the plan premises can safely hold is 450. July 27, 2012. (D) For downward egress travel, stair width shall be based on the total number of occupants from stories above the level where the width is measured. These calculations give you the required COMBINED width of all exit stairs serving that floor. Step 2 . Step (stair tread) width is important. Note that when looking for commercial stair standards, one must look at the International Building Code (IBC). For stairs serving a single user (typically private residential), a minimum of 36” (91 cm) is required. COMMERCIAL STAIR WIDTH. 1005.3.1 Stairways  The capacity, in inches, of means of egress stairways shall be calculated by multiplying the occupant load served by such stairways by a means of egress capacity factor of 0.3 inch per occupant. Occupant Load Capacity. OSHA Stairs. OSHA/BOCA/IBC stair conforms to new 2017 standard 42" guards 36" inboard rails 32° comfort angle, conforms to IBC groups F, H, I, S for industrial/commercial uses to 144" Alternating Tread Stair … Connecticut. Calculating the capacity of a current exit is done by measuring its width and doing a calculation to understand how many occupants it can serve. What is the intent of the codes? As some of you are aware, the 2009 IBC deleted the exit width reduction when a building is sprinklered throughout. Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum. Stair Width. Then I edit the circle and give it a radius equal to the radius of the stair minus the width of the stair … 36” = 120 persons. Calculating tread width of commercial stairways. You'll get detailed drawings, 3D interactive visualization, all necessary stair dimensions (angle, run and rise, risers and treads, no. Landings in all sets of stairs more than 12 feet in … If the stairway serves a floor with an occupant load of less than 50, the minimum clear width is reduced to 36″. Handrails may project into the required exit width by 4-1/2 inches (2012 IBC Section 1012.8 -- similar requirement in older editions, but different section numbers). There is a minimum number of exits that is based on the occupant load per story: The combined width calculation performed above must be distributed between the minimum number of required exits while still meeting the minimum width requirement. Section 1005.3.2 addresses other egress components (such as doors, corridors, aisles, etc.) There is a sprinkler system, but the system was not installed per code requirements. This video talks about the basic procedures of calculating Egress widths for stairs and other egress components such as hallways and doors. Stair Width 1)Except as provided in Sentence (2), required exit stairs and public stairs serving buildings of residential occupancy shall have a width of not less than 900 mm. Stair tread depths shall be 11 inches (279 mm) minimum. That’s it! Objects with leading edges more than 27 inches (685 mm) and not more than 80 inches (2030 mm) above the floor shall not project horizontally more than 4 inches (102 mm) into the circulation path. Note that IBC code for I-3 spaces calls for 5" minimum. If you haven’t read our IBC Stair Width Calculation article, I recommend reading that first so that you can see the IBC codes we reference. STAIR TOLERANCES IBC 1009.7.4 Risers shall be solid and vertical or sloped under the tread above [IBC 1009.7.5]. [2] Do the calculation provisions in 1005.3.2 ("Other egress components") apply to doors only, or to corridors as well? Keep in mind, the minimum clear width is typically 44″, but it is sometimes reduced to 36″ for low-capacity floors. EGRESS WIDTH. However, since we only have two stairways, each stairway must be at least half of the 90″. Calculating Single-Story IBC Stairway Width If you haven’t read our IBC Stair Width Calculation article, I recommend reading that first so that you can see the IBC codes we reference. These sections give requirements on design criteria such as egress width and capacity, allowable riser height, allowable tread depth, headroom, landing size, and stair construction. By Sarah. However, the minimum clear width between handrails is 44″. Stairs come in many different forms, and while building a basic staircase may appear to be a simple task, there are actually a number of parameters, calculations, and building codes that must be considered. The exit is on level 1, but egress from level 1 is in a different location. 1022.1 Exits Once a given level of exit protection is achieved, such level of protection shall not be reduced until arrival at the exit discharge. For stairs serving multiple floors, multiply the occupant load of the floor that serves the most people by 0.3. ... Unit 1 Lesson 3 Stair calculations - Duration: 16:15. Calculating Single-Story IBC Stairway Width. The width of stairways shall be determined as specified in section 1005.1, but such width shall not be less than 44 inches (1118mm). Three questions must be asked: 1. See Section 1009.3 for accessible means of egress stairways. Scenario: We need exit stairs from the second story of a building. The width of IBC stairs can vary, but a minimum of 36 inches is standard for factory industrial and storage occupancies. ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures. see section 1007.3 for accessible means of egress stairways. STAIR. 2012 International Building Code IBC . Summary: calculate the total width per floor you need by multiplying the occupant load by 0.3″ and in some cases 0.2″. Reference the IBC codes below to check your work. Calculating the IBC stair width can be complicated because it is determined by the building’s occupant load, so we have put together this simplified version of the IBC codes. The means of egress width shall not be less than that required by this section. 1005.3.1 Stairways The capacity, in inches, of means of egress stairways shall be calculated by multiplying the occupant load served by such stairways by a means of egress capacity factor of 0.3 inch (7.6 mm) per occupant. If you have already read it, below is a scenario in which we calculate the required width of a multiple stairways serving one floor. ACI 318-99 proposed limiting the spacing and removed actually calculating the width and also removed the exposure conditions. How to calculate stairs. The stair doors probably don’t have to accommodate beds so they would normally have a minimum clear width of 32 inches. Ideally the Occupant Load Worksheet should be completed first, before this worksheet, … You can regulate the step width by changing the nosing. Stairs serving a more significant occupation load (over 50) can be required to have a 44-inch stair width. G — step width (run, going); ... IRC (International Residential Code) for dwellings, for commercial stair standards IBC (International Building Code) – stair code of the United States of America; NBC (National Building Code of India) – for India. Summary: We calculate the minimum required combined width by multiplying the occupant load of the floor by 0.3″, which is 90″. In IBC Code, Uncategorized. 3. The total width of means of egress in inches (mm) shall not be less than the total occupant load served by the means of egress multiplied by 0.3 inches (7.62 mm) per occupant for stairways and by 0.2 inches (5.08 mm) per occupant for other egress components. Then, figure out how many exits are required by referencing the chart above, and divide the required width between the required number of stairways. The width shall not be less than specified elsewhere in this code. 2012 RESIDENTIAL STAIR GUIDE . The population on level 3 is Y. Several components are looked at such as stair width, headroom, riser and tread heights. IF there is a compliant sprinkler system installed throughout the building, multiply the occupant loads by 0.2, not 0.3. BUT in case a stairway is destroyed or inaccessible during an evacuation, the remaining stairway needs to be at least half of the required minimum (144″). That’s a lot of space used for a staircase! In order to access a 12-foot-high platform, an IBC stair would need 21 steps (7-inch rise, 11-inch tread), making the entire horizontal run of the stairs 19.25 feet. 16:15. For stairs serving one floor, multiply the floor’s occupant load by 0.3. However, even with a 36-inch minimum tread width, there is an increased width for stringers, guardrails, handrails, and other clearances. Exception: Handrails are permitted to protrude 4 1 / 2 inches (114 … Interior stairs shall comply with the following requirements: (a) Capacity. Why? If we lose the 46” stairway to a fire, we only have the 44” stairway which is less than half the required width. STAIRS. ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures. Try it, for free! There are formulas for designing comfortable staircases among carpenters - Rule of thumb formulas: ( Rise + Going ) = 17 ½ - 18 inches (44.45 - 45.72 cm) ( 2 x Rise + Going ) = 24 - 25 inches (60.96 - 63.5 cm) (Rise * Going) = 70 – 75 inches (177.8 - 190.5 cm) Handrails shall not project more than 4.5 inches (114 mm) on either side of the stairway PHOTO 2 and the This is complicated, no doubt, but there’s a formula for calculating the tread width. READ MORE . The occupant loads are as follows: Floor 1: 175 occupants Floor 2: 300 occupants. AND if one exit stairway is “lost” (i.e. 1009.5 Headroom. The total width of means of egress in inches (mm) shall not be less than the total occupant load served by the means of egress multiplied by 0.3 inches (7.62 mm) per occupant for stairways and by 0.2 inches (5.08 mm) per occupant for other egress components. Stairways shall not be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height PHOTO 1. The IBC stairs code is not appropriate for industrial and manufacturing spaces. Stairway code requirements are partially detailed in Sections 1005.3.1 and 1011 of the 2018 International Building Code (IBC). Factor 0.3” per occupant. The commercial stair code reflects these diverse users and their needs. The optimum angle ranges from 30° to 40°. IBC 1014.3.1 Part 2: Where the handrail is not circular, it shall have a perimeter dimension of not less than 4” and not greater than 6.25” inches with a maximum cross-sectional dimension of 2.25” and minimum cross-sectional dimension of 1”. (D) For downward egress travel, stair width shall be based on the total number of occupants from stories above the level where the width is measured. In order to build stairs, a calculation for a stair stringer (to what the unit run and unit rise attach) must be obtained. To use our stair calculator, you need to enter the following measurements as a minimum: Total Run – The total horizontal length of the stair stringer; Total Rise – The vertical height between the bottom of the first step and the top of the final step in the stair stringer with two or more flights of stairs, where the risers and treads comply with Section 1011.5, the mini-mum depth of the tread is 13 inches (330 mm) and not less than one handrail complying with Section 1014 is provided within 30 inches (762 mm) of the centerline of the normal path of egress travel on the stair. This is complicated, no doubt, but there’s a formula for calculating the tread width. If you originally have three stairways and lose one, you still have two stairways left. Section 1009 Stairways . [F] 1001.3 Maintenance. 38” = 126 64” = 213 40” = 133 66” = 220 I couldn't find one. STAIR WIDTH FACTOR REQUIRED STAIRWAY WIDTH OTHER EGRESS COMPONENT FACTOR OTHER EGRESS COMPONENT WIDTH Is part of the space shown above an assembly seating facility? International Building Code for Stair treads and risers 1009.3 Stair treads and risers. [1] According to the IBC, doors have an "ultimate" maximum allowable width of 48 inches per (1010.1.1). Careers. A change in elevation, consisting of one or more risers. The exception, per IBC … ... 42” overall stair width. Closed diamond plate treads and risers. The width of interior stairs shall be the clear width between walls, grilles, guards, or newel posts. Posted May 6, 2019. IBC stairs require the most space but are common to use even when the stairs are not a part of the means of egress since they have a lower pitch (around 33 degrees) and are more comfortable for people using the stairs regularly. STAIRWAY HEADROOM IBC 1009.5 CONVENTIONAL STAIRWAY IBC 1009.7.2 All occupancy Groups Except Group R-3 and within Group R-2 Risers shall be solid and vertical or sloped under the tread above [IBC 1009.7.5]. Step 4 . For stairs serving a single user (typically private residential), a minimum of 36” (91 cm) is required. Choose the type of drawing - b&w, color. Floor 2: 300 occupants x 0.3” = 90”. To calculate the egress width of the entire opening for a pair without a mullion, measure between the faces of both doors when open to 90 degrees. A minimum 22″ wide stair . Do corridors and stairs similarly have "ultimate" maximum allowable widths, other than those calculated? Per IBC stair landing requirements, landings must match stairway width. By IBC standards, how do you calc. ACI 318-95 based on statistical method of Gergely & Lutz 1968 limits Z based on exposure. OSHA requires railings on open sides of stairwells and a handrail on at least on the side, preferably the right side descending at 42″ high. IBC Code Analysis for Fire Safety 5 / 7 Example 2.2 Determine the Maximum Egress Travel Distance for each level 2.3 Determine the minimum egress width criteria for doors, corridors and stairs. Therefore, you can add 4-1/2 inches or the distance to a surface, whichever is less, on each side of a stair. the following situation? of steps &etc.). If instead stair angles range from 20° to 30° and from 40° to 45°, the level of comfort will be significantly reduced. However, the calculation can take into account handrails, which can encroach on either side by a maximum of 4.5 inches. Glen Martin 29,939 views. With a 4 week lead-time you can have your IBC stairway installed in no time. For the walk line I draw a circle, snapping the center of the circle to the center point of the stairs. Step 1 . 62” = 206 persons. Calculating exit inches required doors and Stairs for IBC and NFPA, understanding occupant load "Building Code" Select units of measurement - mm, cm, m, inches, feet. Stairways shall have a minimum headroom clearance of 80 inches (2032 mm) measured vertically from a line connecting the edge of the nosing’s. STAIRWAY. The required total stairway width per floor is as follows: Floor 1: Not applicable because this floor is ground level. For stairs serving one floor, multiply the floor’s occupant load by 0.3. Here’s where it is in the 2018 IBC: 1010.1.1 Size of doors. We will need two stairways because we have an occupant load between 1 and 500 per story. Commercial Stairways – 2015 IBC Section 1011 T:\2017 Shared Building Dept Folder\Informational Hand Outs\15 IBC Stairways.doc PLAN ATTACHMENT 1002.1 Definitions- Chapter 2. However, in the 2012 IBC, we see that the reduced exit width factors are back. Exit width for stairs is measured above the handrails. IBC Stair Width Calculation. 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