Firstly these membranes generally share some desirable traits.
Single layer roofing felt.
Asphalt saturated felt starting at the eaves and lapping upper courses over lower by a minimum of 2 inches.
Click to enlarge any image.
Able to meet highly challenging design briefs single layer roofing systems deliver excellent thermal insulation and airtight construction thereby reducing a building s carbon footprint while ensuring high quality protection.
In short any roof covering that can make a flat roof waterproof in one layer unlike roofing felt with its 3 layer system for instance.
Single ply roofing cost.
You can t fit a dpm on the deck first and there is no advantage in it in any case.
Single ply roofing is priced per square foot and an average price for materials and installation of a 60 mil roof may range from 3 to 5 per square foot.
Single layer roofing membranes.
Single layer bitumen roofing membranes deliver high performing lightweight flexible roofing systems which are also easier safer and quicker to install.
Roofing felt offers an additional layer of protection against the elements.
In a single coverage felt installation the lower edge of each course overlaps the previous course by a minimum of 2.
Vertical joints should lap a minimum of 4 inches and be offset by at least 6 feet in successive rows see figure 2 2 at left.
Most shingle warranties do not apply when shingles are layered over existing roofing according to internachi.
Sometimes called roofing felt underlayment roofing tar paper or roll roofing this is a layer of protection installed between the roof deck and the roofing shingles.
Some roofers install a layer of waterproof shingle underlayment wsu over the existing shingles at the eave end as would be done for a roof laid on bare sheathing.
That s because on roofs like the one in the photo with slope of 4 12 or greater only a single layer of felt is required under asphalt shingles.
Felt done properly should last more than 10 and up to 25 years in the right place.
For decades roofers have fitted a layer of felt over a roof s sheathing or roof deck before installing shingles.
This provides added protection against ice dams.
However installing new flashings including special drip edge flashings made for reroofing will ensure a tight seal and a long life.
What is a single ply membrane.
Why roof shingles work best in single layers the temporary savings you receive from adding a second layer of shingles does not outweigh the negative aspects.
One layer is bonded to the deck and then another one or two laid on that.
On roofs with a slope of 4 12 or greater use a single layer of 15 lb.
