1 Total costs (materials plus shipping and labor) for installing a straight, return or L-shaped stair can run $1,300-$7,000 or more. 2  Materials plus labor for custom-built wooden stairs, such as a sweeping circular or elliptical design, can cost $10,000-$30,000 or more, depending on the size, style and type of wood.
Make another bleach solution and pour it onto the driveway. Wait 20 more minutes for the bleach to kill the mold. Rinse the driveway thoroughly with a garden hose. Prevent future mold with a borate solution. Mix 1/4 cup of borate detergent with 1 gallon of warm water in a bucket. Pour the solution onto the driveway and allow it to dry. Don't rinse it.
But if you are concerned, first clean the mold with soap and water. Then, spray the mold liberally with rubbing alcohol and allow the alcohol to sit on the mold for 15-20 minutes. Spray again with alcohol and rub off with a paper towel, then give the mold another wash with dish soap and water.