What This Guide Covers
This article is written for contractors, facility managers, and architects who need to bring existing or new commercial door thresholds into ADA compliance using interlocking wheelchair ramps. Whether you are managing a school renovation, retrofitting a healthcare corridor, upgrading a retail entry, or closing out a punch list on an industrial facility, getting the threshold transition right is one of the most frequently cited ADA deficiencies in commercial buildings. This guide explains the code context, sizing considerations, installation realities, and common mistakes to avoid.
What Is a Threshold Wheelchair Ramp?
A threshold wheelchair ramp, sometimes called an ADA door ramp, threshold ramp, or door transition ramp, is a low-profile wedge-shaped device that bridges the vertical change in level between a floor surface and a raised door threshold. These ramps are surface-mounted, require no cutting or frame modification, and are designed to create a smooth, beveled transition that a wheelchair, walker, or mobility device can cross safely and with minimal force.
Interlocking designs allow two ramp sections to pair together so both the approach side and the egress side of the threshold are addressed in a single installation, keeping the assembly stable and preventing shifting under traffic.
Why Threshold Transitions Fail ADA Inspections
The ADA 2010 Standards and ICC A117.1 are specific about floor-level changes at doors on accessible routes:
- A vertical change in level of 1/4 inch or less may be left square (vertical edge).
- A change between 1/4 inch and 1/2 inch must be beveled at a slope no steeper than 1:2.
- Any change over 1/2 inch must be ramped at a slope of 1:12 or less.
- The maximum threshold height for doors on accessible routes is 1/2 inch. Existing or altered thresholds may reach 3/4 inch if beveled on each side with a slope no steeper than 1:2.
In practice, older commercial buildings frequently have thresholds that exceed these limits, and even new construction can create a non-compliant transition if the finish floor height was not coordinated with the frame and threshold selection early in the project. Threshold ramps are the most practical retrofit solution when tear-out or frame replacement is not feasible.
Sizing Matters: Width, Height, and Fit
A common specification error is selecting a threshold ramp based only on height without confirming width. A ramp that is too narrow leaves exposed edges on either side of the door opening, which can snag wheels or create a tripping hazard. As a general rule:
- Ramp width should match or slightly exceed the clear opening width of the door.
- ADA requires a minimum 32 inches of clear opening width for swinging doors (measured at 90 degrees, face of door to stop).
- Ramp height must correspond to the actual measured threshold rise, not the nominal threshold height. Measure on-site before ordering.
- On interlocking two-piece assemblies, confirm that both approach and egress sides are accounted for, especially on double-egress corridors and cross-corridor doors.
For example, a ramp that is 27 inches wide would be under-width for a standard 3-foot commercial door (which produces roughly 34 inches of clear opening). Match the ramp width to the actual clear dimension of the specific opening, not a generic door nominal. Always field-measure.
Installation Realities for Contractors
Threshold ramps are surface-mounted, making them one of the faster accessible hardware upgrades to execute. That said, a clean install requires attention to a few details that get skipped in the field:
Floor Substrate and Adhesion
- The floor surface under the ramp must be flat, clean, and free of debris. Uneven concrete or curling vinyl tile will cause the ramp to rock, creating a trip hazard rather than eliminating one.
- Most manufacturers provide adhesive tape or recommend construction adhesive for permanent installations. Confirm whether the application is intended as permanent or removable before bonding.
- On smooth hard floors (polished concrete, ceramic tile, LVT), skid-resistant backing is important. Check the product for non-slip underside treatment.
Door Clearance and Sweep Interaction
- Before installing a threshold ramp, verify that the door closer is adjusted so the door does not drag or bind across the ramp surface. A ramp that is taller than the door's undercut clearance will require door closer backcheck adjustment or a door sweep replacement.
- ADA requires a minimum of 5 seconds for a door closer to sweep from 90 degrees to 12 degrees from latch. After any threshold modification, re-test closing speed and opening force. Interior non-fire doors must not require more than 5 pounds of force to open.
- If the existing door has a surface-mounted door bottom or automatic door bottom, the ramp profile height must be compatible with the sweep's ride height.
Interlocking Ramp Alignment
- On interlocking two-piece designs, the two halves must be aligned squarely so the joint does not create a raised lip. A misaligned joint defeats the purpose of the assembly.
- Secure each piece independently before engaging the interlock so neither piece is pulled out of position by the connection.
Applications by Building Type
Schools and Educational Facilities
K-12 and higher education campuses often have older threshold conditions that predate modern ADA standards. Gym entrances, cafeteria thresholds, and exterior corridor doors are common problem locations. Budget-conscious facilities teams appreciate that a quality threshold ramp is a fraction of the cost of threshold replacement and can be installed without disrupting the school day.
Healthcare Construction and Renovation
Patient corridor doors, exam room entries, and accessible restroom thresholds in hospitals and outpatient clinics must meet both ADA and facility-specific life safety requirements. Interlocking ramps provide a stable solution in high-traffic rolling-equipment environments, such as hallways where hospital beds, IV poles, and supply carts pass frequently.
Retail and Hospitality
Storefront entries and service corridor doors in retail environments often have exterior threshold conditions subject to water intrusion, which complicates compliant threshold design. Threshold ramps used in conjunction with properly specified thresholds and door sweeps from the DoorwaysPlus accessible hardware inventory can close this gap efficiently.
Industrial and Warehouse Facilities
Maintenance teams at industrial sites frequently encounter threshold conditions at office-to-warehouse transitions, break room entries, and accessible restroom doors. Heavy-duty threshold ramp materials rated for high-traffic applications are the appropriate choice for these environments, where lighter-duty residential-grade products will fail quickly.
Coordinating the Full Accessible Door Assembly
A threshold ramp is rarely a stand-alone fix. An accessible door opening functions as a system. When specifying or retrofitting a threshold ramp, review the complete assembly for compliance:
- Door closer: Confirm opening force at or below 5 lbf for interior non-fire doors. Preferred closer lines such as Norton, Hager, and Corbin Russwin offer adjustable spring tension and backcheck that make ADA compliance straightforward to dial in.
- Lever hardware: ADA prohibits round knobs on accessible routes. Lever handles, loop pulls, and paddle-style trim are acceptable.
- Maneuvering clearance: ICC A117.1 Figure 404.2.3 specifies required floor clearances on the pull and push sides of the door. A ramp installed without confirming the full clearance envelope may still leave the opening non-compliant.
- Threshold and sweep system: In new construction or full retrofits, coordinating the threshold height from the outset with a product such as those from Pemko or Hager eliminates the need for a ramp addition later.
DoorwaysPlus carries accessible door hardware across all of these categories, from thresholds and door bottoms to closers and lever trim, so you can spec a complete compliant opening in a single order.
Common Mistakes to Avoid
- Ordering by door nominal instead of measured clear opening width. Always measure the actual clear opening.
- Ignoring the egress side. Both approach and egress transitions must be addressed on accessible routes.
- Skipping door closer re-adjustment after installation. A ramp changes the effective floor height and may cause the door to drag if the closer sweep is not checked.
- Assuming a ramp solves all accessibility deficiencies. Document the full opening condition and address maneuvering clearance, hardware, and closing force as a complete system.
- Using a residential-grade product in a commercial application. Material durability and load ratings matter in commercial and institutional traffic volumes.
Specify with Confidence
Getting threshold transitions right protects building owners from ADA complaints, simplifies inspections, and most importantly creates a genuinely accessible environment for every person using the building. If you are putting together a hardware schedule or planning a retrofit scope, the team at DoorwaysPlus can help you match the right ramp dimensions and materials to your specific opening conditions alongside a complete accessible hardware package.
Browse threshold ramps, door closers, accessible lever trim, thresholds, and door sweeps at DoorwaysPlus.com or contact us to request a quote for your project.