Rounded Stair Riser Base
As you can see here in this
picture we used a piece of 1-1/8 inch plywood for our rounded stair
riser base which was scrap from our stair treads after we cut them. You
look closely you can see the glue losing out to the bottom in between
the concrete and the plywood. You can also use shots and pins to fasten
the plywood to the concrete.
Round Stair Tread And Riser
Upper Rounded Stair Tread
If you look in the picture you will see 2 shots and pins one to the right and one to the left attached to the 2 x 4 treated material. Make sure that the rounded base is held back three quarters of an inch so when you nail the plywood strips for the risers they will be flush or even with the front riser.