Determine the primary purpose of the ramp (e.g., vehicle access, wheelchair access).
Measure the height difference between the garage floor and the ground to determine the necessary length and slope of the ramp. The Americans with Disabilities Act (ADA) recommends a slope ratio of 1:12 for wheelchair ramps, meaning 1 inch of rise per 12 inches of ramp length.

Decide on the material for the ramp. Common options include concrete, wood, aluminum, and steel. Each material has its advantages and considerations such as durability, cost, and ease of installation.

Sketch a design plan for the ramp, including dimensions, slope, and any additional features such as handrails or non-slip surfaces.

Review local building codes and regulations to ensure compliance with any legal requirements for ramp construction.

Depending on the chosen material, gather the necessary supplies. For a concrete ramp, you'll need concrete mix, rebar or wire mesh for reinforcement, and forms to shape the ramp. For a wooden ramp, you'll need treated lumber, screws or nails, and non-slip treads.

Essential tools might include a measuring tape, level, hammer, saw, drill, trowel (for concrete), wheelbarrow, and protective gear.

Remove any obstacles, debris, or vegetation from the construction area. Ensure the ground is level and compact.

Use stakes and string to outline the ramp’s footprint. Double-check the measurements to ensure accuracy.

Excavate the area within the marked layout to the required depth, usually about 6-8 inches for a solid base.

Set up wooden forms to shape the ramp. Secure the forms firmly to ensure they hold the concrete in place during pouring.

Lay a gravel base within the excavated area for proper drainage and stability. Compact the gravel to create a solid foundation.

Place rebar or wire mesh within the forms to reinforce the concrete and prevent cracking.

Mix the concrete according to the manufacturer’s instructions. Pour the concrete into the forms, starting at the lower end and working your way up.
Use a trowel to spread and level the concrete, ensuring a smooth surface.

Use a float to smooth the surface and a broom to add a non-slip texture.
Allow the concrete to cure according to the manufacturer's guidelines, typically 24-48 hours.

Cut the treated lumber to the required dimensions. Construct the frame of the ramp by attaching the side rails to the support posts.
Attach the cross beams to the side rails at regular intervals for stability.

Secure the decking boards to the frame using screws or nails, leaving a small gap between boards for drainage.
Ensure the surface is even and smooth.

Install handrails if necessary, ensuring they are sturdy and at a comfortable height.
Attach non-slip treads to the ramp surface for added safety.

Thoroughly inspect the ramp for any structural issues or uneven surfaces. Ensure all components are securely fastened.

Address any issues identified during the inspection. For concrete ramps, patch any cracks or uneven areas. For wooden ramps, tighten any loose screws or nails.

Periodically inspect the ramp for signs of wear and tear, especially after harsh weather conditions.

Keep the ramp clean by removing debris and, if necessary, using a pressure washer to clean the surface.

Promptly address any damage, such as cracks in concrete or loose boards in wooden ramps, to maintain safety and functionality.
By following these steps, you can successfully install a garage.