As a homeowner, when you're told that your home's roof needs repair or replacement, your first concern is probably going to be about the price. Of course, you will usually get a different price quoted from each roofer you approach, but there are some basics about this job that often affect the price and which can help you better understand how a roofer prepares that quote. Note a few of those basics here, and then you'll be better prepared to have a conversation with a contractor about the price of repairs or replacement for your home's roof.
Roofers often quote a price based on squares, which refers to the square footage of your home's roof, and this number is often rounded up. This isn't any type of scam or an attempt by a roofer to squeeze a few extra dollars from you. Shingles, tiles and other materials may get damaged during the installation process, so a roofer will always want some spare materials on hand. In some cases, they will even leave you with leftover tiles, so you can use them when a shingle eventually blows away or otherwise needs replacing.
Note, too, that shingles and other roofing materials are sold in certain quantities, so it may not be possible for your roofer to order the exact amount needed for your roof's actual size. To ensure they have what they need, a roofer will typically round up to the next batch quantity available.
The pitch or angle of your roof affects the type of tiles available for repair or replacement. On very steep roofs, tiles actually need to slow down the flow of water so that the gutters don't overflow. Your roofer may need to apply tiles with larger granules or lay a metal roof with more trenches that stem the flow of water. As with square footage, don't assume that a roofer offering you a limited number of options for your roof is just a way to get more money; understand that this is to protect your home from potential water damage.
Putting tile over the current roof without tearing off the old tile can save you money, but a roofer will need to hammer down any bubbling and other such imperfections before adding that new roofing layer. Fixing these imperfections is called telegraphing, and the more that needs to be done, the bigger the job for a roofer. This is another factor that will affect your price, and you may see this work included in your re-roofing quote.