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Ramps are the change families most often assume will be simple, and then discover is a construction project. The reason is arithmetic.
Key figures
- 4 feet Example: ramp run for a 4-inch rise
- 7 feet Example: ramp run for a 7-inch rise
- 30 feet Example: ramp run for a 30-inch rise
The slope rule
The 2010 ADA Standards for Accessible Design, which govern public buildings, set a maximum slope of 1:12 for ramps: one unit of rise to twelve units of run. In plain terms, every inch of height needs a foot of ramp.
They also set other requirements worth borrowing at home: a clear width of at least 36 inches between handrails, level landings at the top and bottom, landings where a ramp changes direction, and handrails on ramp runs that rise more than a small amount.
Those standards apply to public accommodations and commercial facilities. They are not a legal requirement for a private house. They are, however, the most reliable guide available to what a person can actually push a wheelchair up or walk down in the rain.
The arithmetic, worked
Measure the total rise from the ground to the threshold, not the height of one step.
| Rise | Ramp length at 1:12 | What that means |
|---|---|---|
| 4 inches | 4 feet | A single step, easily solved |
| 7 inches | 7 feet | One typical step |
| 14 inches | 14 feet | Two steps, plus landings |
| 21 inches | 21 feet | Three steps: a substantial structure |
| 30 inches | 30 feet | Usually needs a turn and an intermediate landing |
- 4 inches4 feet
- 7 inches7 feet
- 14 inches14 feet
- 21 inches21 feet
- 30 inches30 feet
Sources cited in this article: US Department of Justice, US Access Board, US Department of Veterans Affairs, Internal Revenue Service. Values reproduce the table; consult its scope and exclusions.
- One step, 7 inch rise7 feet
- Two steps, 14 inches14 feet
- Three steps, 21 inches21 feet
- Porch at 30 inches30 feet
Calculated from the maximum 1:12 slope in the 2010 ADA Standards for Accessible Design: one foot of ramp per inch of rise. Landings at the top, bottom and any turn are additional.
Add the landings: typically 5 feet at the top so a door can be opened while standing or seated on the level, 5 feet at the bottom, and a level square where the ramp turns.
That is why a three-step porch becomes a 30-foot construction with a turn, and why many households end up looking at a different entrance, a different door, or a lift.
The options, from smallest to largest
Threshold ramps. Rubber, aluminium or timber wedges for a single small step or a raised door sill. Inexpensive, removable, and the right answer far more often than people expect. Check they cannot shift and that the door still opens over them.
Portable folding ramps. For a couple of steps, usually with a vehicle in mind. Useful for occasional access rather than daily use, and steeper than 1:12 in most real installations, which means somebody has to push.
Modular aluminium ramps. Bolted systems with handrails and landings, hired or bought, installed in a day and removed later. Often the best value where the need may be temporary or where planning permission is awkward.
Built timber ramps. The traditional answer, and the one volunteer groups often build. Needs good detailing to avoid becoming slippery, and needs handrails and a non-slip surface.
Concrete. Permanent, low maintenance, expensive to change your mind about.
A lift. Where the rise is large and the space is not there, a vertical platform lift can be the only workable answer.
Check the other doors before building anything. Many houses have a back or side entrance with one step instead of three, or a garage with a nearly level route. Moving the accessible entrance is frequently cheaper than ramping the front door, and it is the option most often missed because the front door feels like the entrance.
Details that decide whether it works
- Surface. It must grip when wet and when frosty. Bare smooth timber does neither.
- Edge protection. A raised edge stops a wheel running off the side.
- Handrails on both sides, at a height the person can use, continuing through the landings.
- Drainage, so water does not sit on the ramp or run into the door.
- Light at the top and along the run, on a switch reachable from outside and inside.
- Snow and ice, where relevant: who clears it, and can it be cleared from a seated position?
- Permits. Many jurisdictions require one for a permanent ramp, and some have rules about setbacks. Ask before building.
Paying for it
A ramp is the single most commonly funded item in this field. The VA’s HISA grant explicitly lists construction of permanent ramping among the improvements it covers. Medicaid waivers in most states cover ramps as an environmental modification. Many counties have a volunteer ramp programme through the Area Agency on Aging, and the IRS treats constructing entrance or exit ramps as an improvement that does not usually increase a home’s value, so the full cost can count as a medical expense for households that itemise.
In other words, ask before paying. This is the item most likely to be covered by somebody else.
Related reading: Older Eyes Need More Light Than You Think and What to Ask Before Buying a Stair Lift.
Questions people ask
How long should a wheelchair ramp be?
At the 1:12 slope used in the federal standards for public buildings, one foot of ramp for every inch of rise, plus level landings at the top, the bottom and any turn. A 21-inch rise, roughly three steps, needs about 21 feet of ramp before landings.
Do ADA ramp rules apply to my house?
No. The 2010 ADA Standards apply to public accommodations and commercial facilities, not private homes. The dimensions are still the best available guide to what is usable and safe, which is why builders and programmes generally follow them.
What is a threshold ramp?
A small wedge in rubber, aluminium or timber that bridges a single step or a raised door sill. It is inexpensive, removable and solves a surprising share of access problems, provided it cannot shift and the door still opens.
Who pays for a wheelchair ramp?
Often somebody other than the family: the VA's HISA grant lists permanent ramping among covered improvements, most state Medicaid waivers cover ramps, and many counties run volunteer ramp programmes. The IRS also treats ramp construction as a fully countable medical expense for those who itemise.
Where these figures come from
- 2010 ADA Standards for Accessible Design US Department of Justice · ada.gov
- Chapter 4: Ramps and Curb Ramps US Access Board · access-board.gov
- Home Improvements and Structural Alterations (HISA) US Department of Veterans Affairs · prosthetics.va.gov
- Publication 502, Medical and Dental Expenses Internal Revenue Service · irs.gov
Figures last checked September 2026.
