Probably the most installed roof in the United States installed by the best roofing company is an asphalt shingle roof. A lot of companies specialize in the installation of asphalt shingles. Asphalt shingles have a long track record and are a proven commodity for roofs. But if you are thinking about installing a specialty roof then you will need to find the best roofing company for that particular installation. For example if you are going to install a slate style roof on your new home then you will need to find the best roofing company to install that slate roof and that is one that specializes in this type of roof. Slate roofs are a specialty roof. A well installed roof will last over 150 years. And you will need a roofing contractor who specializes in installing them or one who is willing to read and learn about them.
An important difference between the roofs decking for slate is it cant be plywood because it wont last 100 plus years. The decking should preferably be of rough sawn lumber one inch thick that is green. This would have to be ordered from a lumber mill. It could also be imported kiln dried softwood sheathing lumber or a few others. Another difference is you should use copper roofing nails. Old roofs used hot dipped galvanized nails and those are acceptable too. The flashing should also be of copper or stainless steel or lead sheeted material. Check out roofing st louis for more info.
A slate roof cannot be walked on. It has to be installed with roof ladders and roofing scaffolding. But also important is something called the headlap. On asphalt shingles there is overlap as there is on slate tiles but what matters is the headlap. With a correct headlap the slate roof will not leak. Slate tiles have a top and bottom, front and back. The top of the slate is covered by overlying slates. When the head is overlapped by two slate courses above it is called headlap. With proper headlap you wont even need a roofing felt. Now would you want that asphalt roofing specialist to install your several hundred thousand dollar slate roof? No you would want the best roofing company that specializes in slate roof installation.