Just measure the length and width of each plane on the roof, including dormers. Then, multiply length x width to get the square footage of each plane. Simply add the square footage of each of the planes together to derive the total square footage of your roof.
How to calculate a flat roof area in square metres. Measure the length and width of the structure from the outside for accuracy. Multiply the two figures to calculate the square meterage of the flat roof. E.G. 4 metres (length) multiplied by 3 metres (width) = 12 square metres in total.
Two feet is the general maximum length for a typical roof overhang. This will protect a roof from most types of damage. Roof overhangs can extend farther than 2 feet, but beyond this length, they begin to lose structural integrity and require external support.
A flat roof is generally any roof with a pitch of 1-10 degrees. That means flat roofs aren’t actually flat. It may look horizontal but often has a minimum slope of 1/4 inch per foot. This allows water to run off the roof to prevent damage.
Roof cost by material type. The average cost for a new asphalt roof in 2021 was about $28,256. Inflation was up 8.5% on average for the last 12 months (ending in March 2022). With this in mind, you can estimate that the average price for an asphalt roof will be about $30,700 in 2022.
The smallest pitch of a roof is 1/4:12, which translates to 1/4 inch rise to 12 inches of run. Such a small pitch can only work with built-up roofing or specialized synthetic roofing. Covered porches that are near trees or in areas with heavy rains should not be covered with a low-slope roof.
If your roof was properly installed, your attic is adequately ventilated, and your roof is maintained, it will get as close as possible to the maximum lifespan. This means you shouldn’t need a replacement for around 20 years or even up to around 50 years (or longer), depending on what kind of roofing material you have.