How-To: How Much to Buy

How Much to Buy

Before you go to the store to purchase roof coating, you will need to measure your roof. Knowing the square footage of your roof helps determine how many pails of Elastek coating you will need. Measure the length and width of the roof to determine the size in square feet by using the following formula:

Length x Width = Square Feet

A good rule of thumb is that every 100 square feet of roof equals one gallon of coating. Be sure to allow for roofing on parapet walls, garages, and porches. Take a simple sketch of your roof with dimensions to your coating dealer for help. Here’s an example roof:


Calculate the square footage of each area and then add them together:


Now, take the total Sq Ft, 2670, and divide it by 100 which equals: 26.7. This means you would need approximately 27 gallons to make one coat of the example roof shown or six 5 Gallon pails (27 divided by 5).

Below is a table with some example square footages to further help you determine how much coating material you’ll need for one coat:


How many coats do you need?

A single, thick application of Elastek roof coating may be adequate if you have a coated roof in good condition. Two coats should be used on new roofs or roofs in worn condition.