Typical nap lengths you'll find at your local homes store include 1/4, 3/8, 1/2, 3/4 and 1 inch. As a general rule, surface texture will determine the nap length to choose. For example, a rough surface like thick drywall texture, stucco, or masonry will require a long nap of 3/4 inch or more to force paint into the uneven finish.