Close all doors and remove all porch furniture and decorations. Sweep the porch clean of excess dirt and debris.
Mix 1/2 cup of mild detergent in a bucket of water. Scrub stains or caked-on debris. A clean porch makes it easier for carpet tape to stick. Let the porch dry thoroughly.
Unroll the carpet and allow it to relax overnight. This will make it easier to lay it out smoothly.
Line the porch edges with carpet tape, sticking one side to the porch bottom and leaving the backing on the tape until the carpet is in place. Place a tape "X" with 6-inch strips every 2 feet across the entire porch. Again, leave the backing on the tape until the carpet is in place.
Sit the carpet on the porch, centering it with all excess carpet hanging over the sides or climbing up against the wall or railings.
Fold half of the carpet over itself, exposing half of the porch. You will work from the center out to prevent bubbles in the carpet.
Work in small sections, unpeeling each "X" one at a time to ensure the carpet is smooth and flat. Roll half out first, leaving the edges unattached until the other side is unrolled and secured to the porch.
Trim the edges with the utility knife in line with the porch edge. Unpeel the tape and secure the carpet edge in place. Repeat on all sides of the porch.
Apply a touch of seam adhesive to the ends of the carpet where you trimmed it to prevent fraying.