Can Shingles Be Used to Level a Floor Before Installing the Subfloor?

Place the 8 foot level on the floor throughout the room to determine the areas that have a considerable slope or unevenness. Start from one wall, placing the level on the ground and slowly move across the floor taking note of significantly uneven areas. Cut a piece of string that stretches across the length of the room. Hammer a nail into the two opposing walls one inch from the established floor level. Tie each end of the string to each nail so that the string is taut. The string allows you to visualize large dips in the established ground.

Lay out the initial layer of one-sixteenth inch roofing shingles in the depressed area that will go underneath the subfloor. Cut shingles in half or quarters to mimic the edges of the depression when necessary using a roofing blade. Only place roofing shingles in depressed areas. There is no need to cover the entire floor in the initial layer.

Lay a second layer of roofing shingles on significantly depressed areas over top the initial layer of shingles. Continue to fill in the most depressed areas slowly diminishing the number of roofing shingles near the edge of the depression. There should be a fair amount of overlap in each layer in order to even out the depressions in the flooring.

Double check the evenness of the floor as you continue laying out the roofing shingles with your eight foot level. Place the level on top of the roofing shingles and onto the rest of the level flooring. Fill in areas that remain uneven.

Place the subfloor materials, such as plywood, over the roofing shingles as you would on an unmodified flooring project.