Any outside project needs to be made using treated lumber. Using 2x4’s I built a ramp that rested on the top step and 3 2x4’s ( with a center one also) then 3/4” outdoor plywood for the ramp top, sloped 1”x12” ( like stated by Cheryl above). Add sand mixed into the paint to prevent slippery surface accidents.
How to make a ramp over existing stairs:
https://www.hunker.com/12000691/how-to-make-a-ramp-over-existing-stair-steps
Do you want it for a wherlchair, as in ADA Compliant?
If so, not only will the slope need to be 4.8 degrees or 1:12, which means 1” of rise for every 12”.
One can buy all kinds of aluminum ramps in various widths and lengths for much much less than ones’ time and materials are worth.
LMK if you’re having trouble finding them.
Making it by hand with untreated lumber is a waste of time if you expect it last more than two winters, based on my experience.
Any outside project needs to be made using treated lumber. Using 2x4’s I built a ramp that rested on the top step and 3 2x4’s ( with a center one also) then 3/4” outdoor plywood for the ramp top, sloped 1”x12” ( like stated by Cheryl above). Add sand mixed into the paint to prevent slippery surface accidents.