Roll roofing is a common product chosen to cover low slope roofs. It is a rather inexpensive roofing material often installed over #15 felt underlayment by DIY homeowners. While it can, and has been, used for residential roofs, it is primarily used on utility structures.Click to see full answer. Thereof, does roll roofing need underlayment?While it is not necessary to install an underlay with roll roofing, it is inexpensive and adds a layer of protection that makes it worthwhile. Roll out the underlay and tack it down, making sure that it is flat and smooth, not buckled or wrinkled anywhere.Subsequently, question is, do you nail down roll roofing? Nail the roofing in place with short roofing nails spaced 6 inches apart and 1 inch in from the outer edges of the roll roofing. Add a second piece of full-width roll roofing over the first. Nail it in place with roofing nails spaced 6 inches apart and placed 1 inch from the edge. Accordingly, do you need roof felt? Roofing felt is usually required under roof tiles to prevent the desk from being exposed, it also may be applied as your roof deck may not lie perfectly straight. A layer of roof felt gives you an even surface to install tiles/shingles.How many rolls of roofing felt Do I Need?Rolls of felt coverage for roofs is sold in rolls that are one square each. One roofing square equals to 100 square feet. Always double check with the roofing calculator to make sure that you have enough felt to cover the entire area of the roof.