Commercial Door Thresholds
What is a commercial door threshold? A commercial door threshold is a threshold that meets specific building codes in order to cover, or fill the gap between the floor and the door. Thresholds are typically extruded out of aluminum, bronze, stainless steel and many other finishes. Because thresholds are typically extruded this means the cross section of a threshold is the same at any point in the threshold. This is why thresholds are typically shown with a side view diagram, as this contains all the dimensions that are consistent, no matter what length of the threshold you need. The two main dimensions of the threshold that are typically most important are the height and the width of the side view. These dimensions will determine the footprint of your threshold. Commercial door thresholds come in many different styles including saddle, half saddle, bumper seal, offset, ramp and many others. We will go over the different types of thresholds below so you can determine the proper threshold you need. In the diagram below, we illustrate the main types of commercial grade thresholds.
Saddle Thresholds are the most common type of threshold on the market. This is what is commonly used for doors, and transitions between two different surfaces. Saddle thresholds are symmetrical and of a trapezoidal shape. This type of threshold is typically offered in 1/4" and 1/2" heights to meet ADA requirements. Please see ADA Threshold Requirements section to learn more. Saddle thresholds are typically 2" to 10" wide, just enough to span a door or hide an expansion joint. In terms of visual appearance, saddle thresholds can come in smooth top finishes, fluted, or even coated with an anti slip coating to prevent any injuries in outdoor, or weather exposed applications.
Smooth top saddle thresholds
This threshold has a smooth finish, and is not textured at all for grip. These are typically used mainly for aesthetic purposes as there is no real advantage in structural integrity or slip resistance. Smooth top is usually only available for more narrow profile thresholds or specialty stainless steel or bronze thresholds. They are usually not comprised of any type of reinforcing ribs or material underneath. This is why smooth top aluminum thresholds are typically narrow and have a thicker profile. The reason specialty thresholds like stainless steel are offered in wider profiles, Again, this finish is mainly for aesthetic purposes over functionality.
Fluted saddle thresholds
The most widely used saddle threshold. Fluted thresholds have textured ribs across the top, and sometimes down either ramp side of the saddle threshold. The main reason for this is to increase rigidity and add extra grip to prevent slip.
Anti slip coated thresholds
Anti slip coating has many different names in the commercial hardware industry, but they all have the same function. The anti slip coating is a slip resistant textured surface coating that is applied to the surface of the threshold. Some anti slip coatings actually embed small particles of hot nickel and titanium onto the surface of a threshold by use of a high pressure thermo electrostatic process. By using this process the coating has an extremely high bond strength and excellent resistance to oxidization. This is the ideal choice for a threshold in a weather exposed environment where rain or water can cause a challenge in maneuvering into and out of doorways.
Heavy Duty Thresholds ANSI BHMA A156.21
Heavy duty thresholds are thresholds that meet or exceed ANSI BHMA A156.21. ANSI A156.21 is a certification for heavy duty thresholds that comply with American National Standard for Thresholds heavy duty 10,000 lb. load test. What that means is that this threshold can withstand 10,000 lbs without deflecting or failing. Heavy duty thresholds are typically used in applications where heavy objects, like cars, forklifts, or other objects heavier than 1,000 lbs at a time are moving over the threshold. These are used frequently in car dealerships, warehouses and many others. You can easily tell a heavy duty threshold from a standard duty or residential grade threshold by the thickness of the extrusion. You can see that the typical wall thickness (measurement of the thickness of the the threshold at its top surface) is usually much thicker, and there are ribs present for added support(s) depending on the width and height of the threshold. The diagram below illustrates the same threshold, but one is the heavy duty model, while the other is a standard duty model. The heavy duty model on the left has 50% more typical wall thickness than its standard duty counterpart. You can also see that the heavy duty threshold has an added support near the center of the threshold. Supports are placed strategically to minimize the deflection when the threshold is under load. In this particular threshold, the support is offset because the mounting holes run down the center of the threshold. In any case by adding more material and the support, you get the heavy duty threshold that can support 10 times the weight of its counterpart. 10,000 lbs vs. 1,000 lbs.
Half Saddle Thresholds
Half saddle thresholds are a threshold with only a single ramp on one side of the threshold and a flat top. The opposite side of the ramp is exposed. Because of this characteristic, this type of threshold is typically used to butt up against another surface, almost used as a small ramp. These work well in mating two uneven surfaces typically against tile, or some other finished flooring. Half saddle thresholds typically range from 1/4" to 3/4" heights and widths of 2" to 5". Half saddle thresholds are very similar to offset thresholds and are often organized into the same category because they accomplish the same task. That task being mating two different surfaces together in a smooth transition. If you would like to learn more about offset thresholds and the differences, please see the offset threshold section below.
Carpet / Tile Divider Thresholds
Carpet / tile divider thresholds are intended to be used as a transition between two different types of flooring or connecting seams. There are many different profiles of dividers, and there is no standard shape or profile to them, as they are made to be used in special applications. Some carpet dividers will actually hold the carpet in place, or slide into the threshold to create a seamless looking profile. Carpet / tile divider thresholds are available in many different materials, from standard aluminum to vinyl. These special purpose commercial thresholds are not as common as its counterparts, but are very useful for creating a smooth transition. Below is the typical profile of a carpet / tile divider. As illustrated below, you can see that one distinctive trait about these thresholds is the raised ends on both sides of the threshold. The center supports These are meant to have the finished floor under each side of the threshold to close the gap.
Ramp thresholds are ADA compliant thresholds that gradually inclines on one side and is a flat drop on the opposite side. These are meant to compensate for elevation changes in commercial applications. There are several requirements for commercial buildings to meet these standards.
- Ramps can have no more than a maximum slope of 1:12 (1 inch of vertical rise every 12 inches of horizontal length)
- Ramps must be a minimum of 36 inches wide, some applications or areas may require wider
- All edges must be protected to keep anyone from slipping off
- All ramps shall have top and bottom landings as wide as the ramp itself and at least 60" in length
- Ramps must have handrails on both sides if their rise is greater than 6 inches or length is greater than 72 inches
- ADA does recommend ramps have a 1:16 or 1:20 slope to make entry and exit more accessible
Ramp thresholds fall under both thresholds (1/2" height or under) and ramp (3/4" and over) ADA guidelines. Under 1/2" vertical rise, thresholds to not need to abide by the 1:12 maximum slope to meet ADA requirements. For a 1/2" vertical rise you can use a ramp threshold with as small of a horizontal length as 4". ADA guidlines for thresholds are shown below.
- Thresholds cannot exceed 3/4" in height for exterior sliding door applications or 1/2" in height for all other types of doors
- Any elevation level up to 1/4" can be vertical and does not need an edge treatment
- Elevation changes between 1/4" and 1/2" must have a beveled slope equaling 1:2
The image below displays two different ramp thresholds that meet ADA compliance. The threshold on the left meets ADA compliance due to the threshold guidelines, where the larger unit on the right meets ADA compliance under the ramp guidelines.
Offset thresholds are meant to connect two different floor elevations to make a seamless transition. Both offset, ramp and half saddle thresholds all accomplish this exact same task, but do it in different ways. An offset threshold acts almost like a bridge to fill the elevation difference between two different height floors, by spanning either side of the transition and creating two different sized ramps on either end. This usually results in the top flat portion of the threshold as the highest point in comparison two the two floors you are spanning and the ramps on either side having two different slopes. Offset thresholds are meant to give the appearance of a saddle threshold. They have a flat top and taper down on either side of the flat surface. If you are in the market for an offset threshold, one of the main dimensions you need to be concerned with is the offset. This dimension comes from the elevation change you are trying to span. The image below demonstrates this offset dimension and how to measure for it to find the correct offset threshold.
Because offset thresholds can be used for large differences in elevations, these do not always meet ADA requirements. If you are using an offset threshold that has an offset of 1/4", this will meet ADA compliance. However, anything over 1/4" usually results in a non ADA compliant threshold. The reason for this is that the height of offset thresholds can be determined by the offset + 1/4". So if you are trying to span a 1/2" gap, the height of the offset threshold would end up being 3/4" tall, which means this would not meet ADA threshold guidelines.
Bumper Seal / Panic Thresholds
Bumper seal / panic thresholds are thresholds used to create a seal between the door and the threshold. Bumper seal thresholds are unique in the fact that they are typically not just a metal extrusion. They also usually contain a channel in the threshold that will allow a silicone, pile, vinyl or other type of seal. This seal is mounted horizontally on purpose to provide contact with a door and create a seal. Because the threshold has a seal built in, this seal is usually off centered so that the door will sit at rest in the middle of the threshold and against the seal. This also means unlike the other thresholds on this list, this threshold will only allow the door to swing one way. This is a useful characteristic for this type of threshold because this allows you to convert a door that swings in or out into just an outswing or inswing door. This also adds a layer of extra security if the threshold does make contact with the bottom of the door. Security comes from the lip that the door rests against, which is basically an extra rabbet for the door to rest against if someone is trying to break the door in by force.
As for standards, many commercial bumper seal thresholds are air infiltration tested to meet ASTM E283 standards. ASTM E283 test determines the air leakage rates of exterior doors under specified differential pressure conditions across the thresholds. Any threshold with this rating will basically provide a much better seal and insulation against the door than a standard bumper seal threshold.
Bumper seal thresholds are generally taller than saddle thresholds due to the channel holding the seal. In a standard bumper seal threshold profile, There is a steep side, which contains the channel that holds the seal and there is a more gradual ramp side that is longer. Most commonly, this type of threshold will not have a flat top, and it will have a ramp on either side of the seal portion. The image below depicts a bumper seal threshold and its typical application.
ADA Compliant Thresholds
ADA compliant thresholds are thresholds that meet the following requirements:
- Thresholds at doorways, shall be 1/2 inch high maximum
- Changes in level of 1/4 inch high maximum shall be permitted to be vertical
- Changes in level between 1/4 inch high minimum and 1/2 inch high maximum shall be beveled with a slope not steeper than 1:2
- Change in level of 1/2 inch is permitted to be 1/4 inch vertical plus 1/4 inch beveled. However, in no case may the combined change in level exceed 1/2 inch. Changes in level exceeding 1/2 inch must comply with ramps or curb ramps.
- Existing or altered thresholds 3/4 inch high maximum that have a beveled edge on each side with a slope not steeper than 1:2 shall not be required to comply with the above lines.
Common Commercial Door Threshold Questions Answered
How thick is a door threshold?
Door thresholds vary in thickness and in height. Typically a standard duty commercial door threshold will be no taller than 1/2" and a typical wall thickness thickness of .11" to .16". Heavy duty thresholds usually have the same height of 1/2" and a typical wall thickness of .25". Again, these are just based on common sizes and applications for commercial use. Thresholds can vary greatly in both height and typical wall thickness.
How high is a door threshold?
Door thresholds are typically 1/2" or 1/4" tall. This is because ADA guidelines state that a threshold cannot be taller than 1/2". However, this is a general rule of thumb in commercial applications. Commercial applications are much more predictable due to the governing requirements. Residential or other applications may not be limited to these same ADA guidelines, so you can expect usually one of the following heights: 1/4", 1/2", or 3/4". Most commonly, when people refer to threshold, they are actually referring to a saddle type threshold. Threshold height can also differ between the types of thresholds. For example Bumper seal thresholds tend to be 1/2" up to 1" tall. This is because of the construction of this type of threshold. Bumper seal thresholds add a seal mounted on top of the threshold which is the only way to allow for a channel in which the seal can be held in. This results in a threshold that is at minimum 1/2" tall. An offset threshold also tends to be taller than the average threshold. this is because it is spanning two different height surfaces. By making a threshold a minimum of 1/4" taller than the higher floor results in a 1/2" (from the lower floor) height at minimum, and some thresholds 1" or taller (to cover a 3/4" height difference in the two floors).
How do you extend a door threshold?
Commercial door thresholds are typically not extendable. If you need to extend a threshold, you would have to remove your current threshold and replace it with a new threshold that fits the wider dimension you desire. Because thresholds are extruded and a standalone item, you cannot piece these together without compromising the integrity and standards / ratings the threshold has.
Does a door need a threshold?
Doors are not required to have thresholds, but they do serve many different purposes. Typically they are used for entrances to increase the rigidity of the door and frame. Thresholds can also be used in conjunction with a sweep to create a weatherproof seal from the outside elements.
What type of door threshold do I need?
The answer to this question depends on what you are trying to accomplish with your threshold. In most cases the threshold people need are a saddle threshold. This is your standard symmetrical commercial door threshold that is used to help close the gap between the door sweep and the floor. Another common type of threshold is the panic threshold which is a threshold with a seal built into it. This is used to create a seal between the door and the threshold. This threshold also will only allow the door to open in only one direction. The last type of common threshold you may need is a half saddle threshold. These thresholds are ramped only on one side. These are meant to butt up against tile, or another type of raised flooring so you have a seamless gap between the two different height floors. These are the most common threshold types and will work in nearly most situations.
Why are thresholds important?
Thresholds help to seal the gap between the bottom of the door and the floor. This usually results in a more energy efficient setup to keep the heat or cold inside the building. Thresholds also create a raised barrier to help make it much harder for water, snow, mud, or other elements to track inside the building. In some cases thresholds are important to meet ADA guidelines and provide a safe transition for the disabled.
How do you seal a door threshold?
A door threshold can be sealed by using a silicone caulk when installing the threshold. The caulk needs to be a continuous bead across the entire length of the threshold, and be generous enough to cover any gaps in the surface you are planning to seal against. Doing this will allow you the best energy efficiency as this will seal any draft that could normally come in underneath the threshold. This method of sealing is also highly recommended for rainy areas where water can easily seep under the threshold and inside your building. Please follow the link here
to follow our tutorial on sealing a threshold.