Many roofing materials out there are measured in their weight per roofing square. Felt is just one of the many materials that is measured like this. For instance, a material that is labeled ‘10# roofing shingle’ would weigh the same as 10 lbs, per square of the roof. Heavier weights will provide you with fewer squares per roll of shingle.
The most common concrete tile out there comprises of around 90 tiles per roof square.
When roofing, it’s easy to make mistakes in the estimation of the amount of roofing material that is required. Even the most experience roofers will have problems when roofing, and can easily make mistakes. There are many contractors out there that will overestimate roofing material, and hence, you should always be careful.
If you’re doing the roofing yourself, however, then there are a couple of things you can do to make sure that you’re measuring correctly, when it comes to a roof square.
Using squares can help simplify the way that you rood, and you should remember that one square will equal 100 sq ft (ie, 10 ft x 10 ft). So instead of thinking that your house will require 2,500 sq ft of material, you should remember that your house would require 25 squares of roofing.