Certainteed rhymes with:
pitied, airspeed, aniseed, appleseed, ashmead, centipede, cottonseed, duckweed, fireweed, flaxseed, ganymede, goodspeed, highspeed, inbreed, krumwiede, linseed, lockheed, milkweed, nobody'd, nosebleed, oilseed, pitied, pokeweed, proofread, ragweed, rapeseed, rosemead, seaweed, siegfried, windspeed
Certainteed sounds like:
carotenuto, certainty, coordinate, coordinated, cordiant, cordoned