Metal roof systems in most cases weigh between 1 to 3 pounds per square foot. The actual weight is dependent upon metal gauge and profile of the panel. Metal roof systems are considered a lightweight roof covering compared to their counterparts. The following illustrates the different types of other roofing materials and their respective weights per square foot:
Asphalt Shingle: 2 - 3.5lbs psf
Textured Asphalt Shingle: 3.5 - 5lbs psf
Wood Shingles/Shakes: 3.5 - 4.5lbs psf
Clay or Concrete Tile: 5.5 - 10lbs psf
When you say roofing felt (or blackout paper) It usually means the felt paper used under asphalt shingles. If that's the case, a couple of inches is fine. If you're really talking roll roofing, then that's a whole different ball game.
Thick asphalt-impregnated paper used for roofing.
Black Knight roofing tar .
The benefit of roofing felt is to provide a simple barrier between the asphalt shingles and the wood sheathing below it. The sap in the wood is not good for the shingles.
15 lb felt is all you need.
Per square what? (Metre? Foot?) You haven't fully asked the question. A "square", when referring to roofing and siding, is 100 square feet.
type I is 15# felt and type II is 30# felt
It protects the roof sheathing from moisture.
Roofing shingles weight between 200 & 250 lbs per square. 1 square = 3 bundles. So if you know how many square of shingles are on a house, you will know about how much the roofing debris will weigh.
You can use roofing nails, but most people use a stapler, it's cheaper and faster. The felt paper is just a base for the shingles/tiles.
Forty-pound roofing felt, also known as #40 felt, typically has a thickness of about 0.30 to 0.35 inches. This thickness can vary slightly based on the manufacturer and specific product, but it is generally designed to provide a durable underlayment for roofing applications. It is heavier and thicker than the more common 15-pound and 30-pound felt options.
It weighs 3 Ibs per one square footage of asphalt shingle