Apply a clear sealer to a cedar deck using a paint roller and extension pole. Apply a single thin coat of the water sealer to a clean dry deck. Choose a day when the forecast for the minimum temperature is 50 degrees Fahrenheit or above for the next several days and there is little chance of rain. Reapply the sealer when water splashed on the deck stops forming beads.
Prepare the deck by sweeping all foreign materials from the surface using a broom or leaf blower. Inspect the cracks between the decking for leaves, needles or other matter between the boards. Use a flat-blade screwdriver or similar tool to remove these materials. For a new deck, rinse the decking with water from a garden hose sprayer. For an older deck, use a pressure washer to remove any deep-seated grime.
If you have materials stored under the deck, cover them with a plastic drop cloth before applying the sealer. After giving the deck a minimum of 48 hours for air-drying, begin the application process. Pour the sealer into a paint roller pan, and apply it to any railings or other trim first. Use a brush for small pieces of trim. Thread the handle into the roller handle, and use it to apply the sealer to the deck surface. Allow at least 48 hours of drying time before use.