Apply a coat of water to the porch with a garden hose so the material is just damp to the touch. A wet porch simplifies the cleaning process.
Protect surrounding plants with drop cloths.
Fill a pump sprayer with a biodegradable deck cleaner. Secure the top of the sprayer and prime the pump as instructed in the user manual.
Hold the wand of the sprayer 4 to 5 inches away from the porch's surface and spread the cleaner evenly onto the damp surface.
Scrub the porch with a nylon-bristled brush to work the cleaner into the material and effectively clean the surface.
Rinse the cleaner off of the porch with a garden hose. Allow the porch to dry fully before continuing.
Clean out the pump sprayer and then fill it with a waterproof sealant. Prepare the sprayer for use and spray the sealant onto the porch evenly. Overlap your passes with the sprayer so that you do not miss any spots. Wait 48 hours after application before using the porch.