Open stair tread design is very beautiful. They give the appearance of the stair floating. They give a light and airy feeling to a sometimes forgotten design element. Do you want an open stair tread in your design? Their are specific requirements for how large the tread needs to be, the minimum and maximum height between treads. Some of the most beautiful stairs have open stair treads. Can you use them in your next project?
Code Analysis – Open Stair Treads
Building codes sections about stairs are very lengthy. They go into detail about length and width of treads, where handrails are needed etc. The code is very clear when open stair treads are allowed . Per IBC 1011.5.5.3, Solid Risers “Risers shall be solid“. Their are a few exceptions to open stair treads.
Solid risers are not required for stairways that are not required to comply with Section 1009.3 provided that the treads do not permit the passage of a sphere with a diameter of 4 inches. (Interpretation – Essentially it means any stairway not required for the exiting of the building or one which is in excess of the required stairs can have open stair risers). Occasionally, you will see a commercial building with a grand stairway in a lobby that has open treads. I believe this is how they are able to achieve this. The 4″ diameter is the same rule of thumb for stair guardrails or guardrails at balconies. This is eliminate the possibility of a small child from slipping between the cracks. Never a good thing.
Solid risers are not required for occupancies in group I-3 or in Group F, H and S occupancies other than areas accessible to the public. The size of the opening in the riser is not restricted. (Interpretation – can occur in industrial, factory, hazardous and storage facilities. This is why you generally see them occur in those conditions.)
Solid risers are not required for spiral stairways constructed in accordance with Section 1011.10.
In residential applications, you will see the majority of the open risers stairs. Some defy gravity and cantilever off the walls. They can be a work of art within a space. This is why, architects push the design envelope in residential design when designing stairs. The IRC, Section R311.7.5.1, specifically states “At open risers, openings located more than 30 inches, as measured vertically, to the floor or grade below shall not permit the passage of a 4 inch diameter sphere. (Interpretation – Open treads allowable anywhere in a residence as long as their is not an opening greater than 4″).
Summary
Open stair treads can add a beautiful element to any architectural design. Can you use this design element? Current code does not allow it in some commercial applications. They are not allowed as a required exit in a commercial project. They are allowed in occupancies such as Industrial, factories, storage facilities and hazardous occupancies. Use them in any of your residential projects. As with all projects, Check with your local jurisdiction to ensure your projects success. As with all design elements, their are exceptions to the rules.
Should my door have panic hardware? – Building Codes
As an Architect, I interact with clients, engineers and contractors who have acquired bits of information about Building Codes. Sometimes, those bits are misconceptions and regurgitated information. The building codes can be intimidating and have no beginning or end. To learn the code, the best way is jumping in feet first.
Upcoming Blog Posts
In the next series of blog posts, I will explore common Building Codes. Each City has adopted a code but most in Arizona use the IBC (International Building Code).
The item in bold are addressed in this post. As an Arizona Architect, most City’s jurisdictions work with the IBC (International Building Code). This code analysis is based upon the IBC.
Should my door have panic hardware?
Panic hardware – ‘A device designed to provide fast and easy egress in an emergency. Where is it required by code?’
Panic hardware is required by code in a few locations. Use it in buildings for its ease of exit. The following are some basics on where it applies:
Doors serving Occupancy ‘H’ – Hazardous
Occupancy ‘A’ (Assembly) or ‘E’ (Education) where occupant load is > 50.
Electrical Rooms with equipment rated at 1,200 amperes or more and over 6 ft wide that contains switching devices or control devices.
Exception – Panic hardware not required for the following:
Main Exit in Occupancy A(assembly) where occupant load is less than 300.
In occupancy types B(business), F(factory), M(mercantile) and places of religious worship, the main exterior doors are permitted to be equipped with key-operating locking devices provided: 1. Locking device is readily distinguishable as locked. 2. Sign adjacent to door states “This door to remain unlocked when building is occupied”
Summary
Should my door have panic hardware? Use them in spaces with large amounts of occupants or in rooms with hazardous conditions. The purpose of panic hardware is to ensure safety and security of a building. Panic Hardware isn’t required in all Occupancy types. It does allow occupants an easy means of egress. Always verify with current codes or specialist to ensure that your condition is code compliant.
As an Architect, I interact with clients, engineers and contractors who have acquired bits of information about Building Codes. Sometimes, those bits are misconceptions and regurgitated information. The building codes can be intimidating and have no beginning or end. To learn the code, the best way is jumping in feet first.
Upcoming Blog Posts
In the next series of blog posts, I will explore common simple and more complex Building Codes. Each City has adopted a code but most in Arizona use the IBC (International Building Code).
The issues addressed in the following Blog Posts are:
Item in bold is addressed in this post. As an Arizona Architect, most City’s jurisdictions work with the IBC (International Building Code). The code analysis is based upon the IBC.
Number of Exits within a Room
The number of exits within a room is determined by the occupancy and the level of hazardous condition. The type of Occupancy (ie. office, retail, industrial etc.) generally determine quantity of occupants based upon a load calculation. For example:
Portion of Occupancy Table
Once the number of occupants is determined, a maximum number of occupants are allowed before second or possibly third exit is required. The general rule of thumb are as follows:
Number of Exits Rule of thumb
In occupancy’s such as business group (offices), Assembly (Theaters, night clubs, restaurants), Educational (Schools), Factory (manufacturing), Mercantile (stores, markets, retail) and Utility (agriculture buildings, barns, sheds), if occupant load stays below 49 people, one exit is required. Other factors may play into the requirement, such as travel distance, but that will discussed in a later blog.
In hazardous occupancy’s, the maximum occupant load is greatly reduced to either 3 or 10, depending upon the use, before a second exit is required. In storage occupancy the number of occupants allowed before a second exit is required is 29.
Once occupant loads reach greater numbers, such as 501 – 1,000 occupants, minimum 3 exits are required. Beyond 1,000 occupants, four exits are required. An example of this may be a large conference room or convention center where spaces are large enough to hold these quantities.
Another requirement to take into account is location of the exits themselves. A good rule of thumb to follow is that the distance separating the exits must be greater than 1/2 the distance of the overall diagonal dimension of the room. So in a large office space that is an open plan with no walls, such as the one depicted below, the number of occupants possible by code would be 12,000 s.f. / 100 s.f. per person = 120 occupants. this exceeds 49 occupants therefore 2 exits required. See graphic below.
Exit calculation
Summary
Number of exits and their separation are dependent upon occupant loads. Once a threshold of occupants are met, exit quantities increase. Separations of those exits are required to allow for occupants to safely exit in time of emergency. For example, if a fire occurs within one side of the room, having adequate separation ensures that both exits are not blocked.
When learning building codes, once you begin digging into the code, it begins to make sense. However when in doubt, rely on an Architect to explore the code and assist you.
