Question 1

How do you calculate the slope of a ramp?

Accepted Answer

Divide the rise (vertical height) by the run (horizontal distance). For example, a 24-inch rise with a 288-inch run gives 24 ÷ 288 = 0.0833, which is a 1:12 slope ratio. The slope angle in degrees is arctan(rise ÷ run) = arctan(0.0833) = 4.8°. The grade percentage is (rise ÷ run) × 100 = 8.3%.

Question 2

What is the ADA ramp slope requirement?

Accepted Answer

The ADA requires a maximum slope of 1:12, meaning 1 inch of rise for every 12 inches of horizontal run (4.8° or 8.3% grade). Additionally, the maximum rise for any single ramp segment is 30 inches — beyond that, a level landing (minimum 60″ × ramp width) is required. Ramps must be at least 36 inches wide, with handrails on both sides when the rise exceeds 6 inches.

Question 3

How do you calculate ramp length from rise?

Accepted Answer

Multiply the rise by the slope ratio denominator to get the run, then use the Pythagorean theorem: Ramp Length = √(Rise² + Run²). For a 24-inch rise at ADA 1:12: Run = 24 × 12 = 288 inches, Ramp Length = √(24² + 288²) = √(576 + 82,944) = √83,520 = 289 inches (about 24.1 feet).

Question 4

What is a 1:12 ramp slope in degrees?

Accepted Answer

A 1:12 ramp slope equals 4.8 degrees. This is the standard maximum slope for ADA-compliant wheelchair ramps. For comparison, a 1:12 slope (IRC residential egress) equals 4.8°, a 1:10 slope equals 5.7°, and a 1:20 slope (ADA preferred) equals 2.9°. Steeper slopes are harder for wheelchair users to navigate safely without assistance.

Question 5

How many landings does my ramp need?

Accepted Answer

Under ADA, you need a landing for every 30 inches of rise. For a 60-inch rise: 60 ÷ 30 = 2 segments, requiring 1 intermediate landing. Under UK Part M, each ramp flight is limited by going distance at the required gradient (2 m at 1:12, 5 m at 1:15, 10 m at 1:20). A single flight within its gradient limit needs only top and bottom landings. ADA requires landings at least 60 inches long and as wide as the ramp. UK Part M uses 1.2 m head/foot landings, 1.5 m intermediate landings, and 1.8 m × 1.8 m passing places when the ramp has three or more flights.

Question 6

What is the maximum rise for a ramp without landings?

Accepted Answer

Under ADA standards, the maximum rise for a single ramp segment without a landing is 30 inches. If your total rise exceeds 30 inches, you need one or more intermediate landings. Under IRC (residential code), there is no strict rise-per-segment limit, but a 1:12 slope is standard for egress ramps. UK Part M limits each flight by going distance (2 m at 1:12, 5 m at 1:15, 10 m at 1:20); a single flight within limits needs only top and bottom landings. Note: Approved Document M requires alternative access (e.g. a lift) when total rise exceeds 2 m, regardless of flight count.

Question 7

How much does it cost to build a wheelchair ramp?

Accepted Answer

Ramp costs vary by material: pressure-treated wood ramps cost $15–$25 per square foot installed ($1,500–$2,500 for a typical 100 sq ft ramp). Concrete costs $20–$40 per sq ft ($2,000–$4,000). Aluminum modular ramps cost $25–$50 per sq ft ($2,500–$5,000). Steel ramps cost $30–$60 per sq ft ($3,000–$6,000). Labor typically accounts for 40–60% of the total cost.

Question 8

What is the difference between ramp slope and gradient?

Accepted Answer

Ramp slope and gradient describe the same thing — the steepness of the ramp — but are expressed differently. Slope is usually written as a ratio (1:12, meaning 1 unit of rise per 12 units of run). Gradient is expressed as a percentage: (rise ÷ run) × 100. A 1:12 slope equals an 8.3% gradient. In the UK and Europe, gradient percentage is the more common convention.

Question 9

What is the best material for a wheelchair ramp?

Accepted Answer

Wood is the most affordable and DIY-friendly option, ideal for residential ramps. Concrete is the most durable and maintenance-free, best for permanent installations. Aluminum is lightweight, rust-proof, and modular — excellent for rental properties or temporary needs. Steel is strongest but most expensive, suited for industrial or heavy-duty applications. Choose based on budget, permanence, and climate.

Question 10

Can I build a ramp steeper than 1:12?

Accepted Answer

Yes, but only in specific situations. IRC (US residential code) allows slopes up to 1:8 for private homes. However, steeper ramps are harder for wheelchair users to ascend safely and may require assistance. ADA-compliant public ramps must not exceed 1:12. Slopes between 1:10 and 1:12 require a 6-inch maximum rise per segment, and slopes between 1:8 and 1:10 are limited to 3-inch rise per segment.

Standard	Max Slope	Landing Rule	Min Width
ADA (US Accessibility)	1:12 (4.8°)	Every 30″ rise	36″
IRC (US Residential)	1:12 (4.8°)	Top + bottom required	36″
IBC (US Commercial)	1:12 (4.8°)	Every 30″ rise	44″
UK Part M	1:12–1:20*	Top + bottom; intermediate for multi-flight	1.5m

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