Roofing felt is an asphalt-infused paper that makes up the middle layer of most typical house roofs. It is generally installed on top of plywood or oriented strand board decking and underneath the top layer of shingles. Roofing felt helps waterproof the decking if water becomes dammed up on the roof and runs back under the shingles. It also provides a slight cushion between the shingles and the decking, making your roof more impact-resistant. Do-it-yourselfers can perform the installation.
Strip the shingles from the roof with a pitchfork or flat shovel. Start at the ridge line and work your way down, scraping underneath the shingles and prying up to release the nails. Slide the shingles over the edge of the roof where they can be picked up later.