Under the 2010 ADA Standards, a threshold at a doorway can be no more than 1/2 inch high (section 404.2.5). A change in level up to 1/4 inch can have a plain vertical edge. Between 1/4 and 1/2 inch the edge must be beveled no steeper than 1:2, and anything over 1/2 inch must be treated as a ramp. Existing or altered thresholds may be up to 3/4 inch high if they have a bevel on each side no steeper than 1:2.
What does the ADA say about thresholds?
The rule sits in section 404.2.5 of the 2010 ADA Standards for Accessible Design, published by the US Department of Justice. It says thresholds at doorways shall be 1/2 inch high maximum. Raised thresholds and changes in floor level at door openings must also be beveled following sections 302 and 303, which cover floor surfaces and changes in level.
In plain terms, the saddle is treated like any other bump in the floor. The taller it is, the more its edge has to be shaped so a wheelchair, walker or cane can get over it.
How high can an ADA compliant threshold be?
The answer depends on how far the top of the threshold sits above the floor next to it. This table follows sections 303 and 404.2.5.
| Height of the change in level | What is required | Section |
|---|---|---|
| Up to 1/4 inch | Allowed with a vertical edge, no edge treatment needed | 303.2 |
| Over 1/4 inch up to 1/2 inch | Must be beveled, with a slope not steeper than 1:2 | 303.3 |
| Over 1/2 inch | Must be ramped, with a running slope not steeper than 1:12 | 303.4 and 405 |
| Existing or altered threshold up to 3/4 inch | Permitted if it has a beveled edge on each side with a slope not steeper than 1:2 | 404.2.5 exception |
Notice that the limit is a height above the floor, not the thickness of the stone. A 3/4 inch thick saddle set down in the same bed as the tile can sit well within 1/2 inch of the floor. Our threshold thickness guide explains how to work that out.
What does a 1:2 bevel actually mean?
A slope of 1:2 means that for every 1 unit the edge rises, it must run at least 2 units across. Steeper than that does not qualify as a bevel under these rules.
- A 1/2 inch rise needs at least 1 inch of horizontal run.
- A 3/8 inch rise needs at least 3/4 inch of run.
- A 3/4 inch rise under the exception needs at least 1-1/2 inches of run on each side.
A longer, gentler run is fine. The rule only sets the steepest slope allowed.
Which marble threshold profiles help with accessibility?
The profile of the long edges decides how a saddle handles a change in level. We cut three:
- Single Hollywood bevel: a long, gentle slope on one long edge. Use it when one floor is lower than the other, with the slope facing the lower floor. This is the usual choice where tile meets a lower wood or vinyl floor.
- Double Hollywood bevel: a long slope on both long edges. Use it when the saddle sits above the floor on each side. This is the shape the 3/4 inch exception describes.
- Standard bevel: a small 1/4 inch chamfer on one long edge only, with the other long edge square. It softens the corner but is not designed as an accessibility slope. Don’t rely on it to meet the 1:2 rule for a step over 1/4 inch.
If you need to document a slope for an inspector, ask us for the profile dimensions of the piece you are ordering before it is cut. You can compare all three on the bevel page.
Does the ADA apply to my home?
Generally, no. The ADA applies to public accommodations and commercial facilities, such as stores, offices, restaurants and hotels. Private homes are generally not covered.
That said, the same dimensions are good practice in any house. A saddle that stays within 1/2 inch of the floor and has a proper slope is easier for older relatives, anyone on crutches, and anyone pushing a stroller or a cart. If you are renovating a bathroom for aging in place, it is worth designing to these numbers from the start.
Some multifamily buildings and other projects may fall under other accessibility codes as well. Always check with your local building department.
How do you plan an accessible doorway with a stone threshold?
- Measure the finished floor height on each side of the door. Our measuring guide shows how.
- Work out how high the top of the saddle will sit above each floor once it is set.
- Keep that height at 1/2 inch or less wherever you can, and at 1/4 inch or less if you want a square edge.
- Choose a single or double Hollywood profile for any rise over 1/4 inch, and check its slope against 1:2.
- Set the stone in a full bed with no hollow spots, so it does not rock. See our installation guide.
- Confirm the plan with your architect, contractor or local inspector before the stone goes in.
Contractors working on commercial jobs can reach us through the contractors page. For an odd length or a thicker piece, request a custom threshold.
What can a stone supplier promise about compliance?
We cut and finish the stone. Whether a doorway meets the ADA depends on how the saddle is set, the floors around it, the door hardware and the rest of the opening. That is why we do not describe any of our products as ADA certified.
What we can do is cut a profile that suits your measurements and tell you its dimensions. The inspector or design professional on your project makes the call on compliance.
Frequently asked questions
What is the maximum threshold height under the ADA?
1/2 inch at doorways, under section 404.2.5 of the 2010 ADA Standards. Existing or altered thresholds may be up to 3/4 inch if they have a beveled edge on each side with a slope not steeper than 1:2.
Is a marble threshold ADA compliant?
A marble saddle can be part of a compliant doorway if it is set at the right height and has a suitable bevel. The stone alone is not compliant or non-compliant. The finished installation is what gets checked, so confirm it with your local inspector.
Does a 1/4 inch step need a bevel?
No. Section 303.2 allows a vertical change in level up to 1/4 inch with no edge treatment. Above 1/4 inch and up to 1/2 inch, the edge must be beveled no steeper than 1:2.
Which bevel should I choose for a wheelchair-accessible bathroom?
Usually a single Hollywood bevel facing the lower floor, or a double Hollywood if the saddle sits above the floor on each side. Keep the rise within 1/2 inch and check the slope. For background on profiles, read what a marble threshold is.
Do I have to follow the ADA in my house?
Private homes are generally not covered by the ADA. Local building codes still apply, and following the ADA dimensions is good practice for anyone with limited mobility. Check with your local building department.