How to Use Polyfilla to Fill Holes on Outside Siding

Use a stiff hand brush to scrub the hole to remove loose dirt and siding debris. Scrape the sides and base of the hole with a utility knife to remove soft masonry or rotten wood.

Clean the hole and surrounding siding area with a damp cloth and a degreaser to remove oil-based dirt deposits. Allow the siding to dry.

Use Polycell Wood Flex Polyfilla for wood siding and use a ready-mix Polycell Multi Purpose Exterior Polyfilla for masonry-based siding, as recommended by Polycell.

Amalgamate the Wood Flex Polyfilla with a stir stick to produce a smooth and uniform consistency. Fill the hole with Polyfilla in a series of 3/8-inch depths, allowing a minimum of two hours for each 3/8-inch layer to dry before applying more Polyfilla. Glide a filler knife across the hole surface on the final layer to create an even finish.

Fill a hole in masonry-based siding in 3/8-inch layered depths. Allow the Multi Purpose Exterior Polyfilla a minimum of one hour to dry before adding another layer. Wet a filling knife with cold water and run the knife over the filled hole surface to provide a flat finish.