How to Repair a Roof With Liquid Rubber

Prepare an EPDM roof for the application of the liquid rubber by removing any flaking coating or loose caulking with a putty knife and a wire brush. Scrape away any roof cement left on the EPDM and replace with a bead of butyl caulk. Repair any tears in the EPDM with a rubber patch. Cut the patch with a utility knife to the size of the tear, and then apply caulk to the bottom. Press the rubber over the tear, holding it in place 30 seconds until it binds to the surface. Wash the entire surface with denatured alcohol and a cloth to remove any oil or wax, and then wait about an hour for the alcohol to dry and the caulk to cure.

Prepare a metal roof for the rubber repair coating by cleaning the surface with a cleanser formulated for metal use. Rinse the cleaner form the roof then allow it to dry for about an hour. Glue down any loose areas of the roofing material using contact cement to hold the area down. Scrub away any rust with a wire brush, and then sand any smooth areas of metal with a coarse sandpaper attached to a sanding block to create texture.

Place a strip of masking tape around the edge of the roof to prevent the liquid rubber from dripping over the side and causing discoloration.

Mix the liquid rubber with an electric drill with a paddle bit attachment. Pour the catalyst into the rubber, following the mixing ratio provided by the rubber manufacturer. Mix the catalyst in thoroughly.

Pour the rubber over the roof. Use a squeegee to spread the rubber in a light layer evenly across the surface. Go over the spread rubber with a paint roller to smooth the rubber out. Allow the rubber to cure to hardness. Cure times will vary according to temperature. Check the manufacturer instructions for applicable cure times for the particular brand of rubber used.

Remove the masking tape to create a sharp line with the edge of the rubber.