There are many ways to screw up a roof installation, but only one way to do it right. I will show you most of the common mistakes and how to avoid them. Read these carefully and watch out for that construction team. If by any chance you are going for the DYI approach you will have to watch steps with even more attention.

1)The first step and one of the most overlooked one is to only build in the right conditions. Roofing under 35 degrees Fahrenheit should never be attempted. This is mostly due to security reasons. You need a dry working area otherwise it can get very slippery. Of course I don't expect anyone to carry a thermometer around, you should always consider common sense. Look at the roof before going on top of it. If it looks moist stay away from it. If you find this to be harsh, try doing something else in the meantime, bring your roofing supplies closer, analyze what has been done so far, do some measurements, resize the materials if needed. Only a fraction from a roof installation is actually done on the roof.

2)Avoid walking on an installed roof. This is critical when it comes to tile or slate roofs. Ant true professional will avoid this at almost any cost and will always have an escape route which doesn't affect the already installed portions of roof. This is a very good way to detect inexperienced roof contractors. True professionals respect their work. Even with metallic sheet roofs, this should be avoided, because although they are very unlikely to break, they can bend and can remain that way.

3)Use a roof consultant. The fee you will pay will probably be one of the best investments you ever made. There are many hidden dangers that can affect the quality of roofing. Getting your facts and priorities has proven time and time again an invaluable factor. Making an informed choice and getting a glimpse in what your future roof should look like is sometimes the best choice available and can save you the cost of many mistakes.

4)Get the flashing right. Flashing is a critical part in regards to a roof's longevity. A poorly made job can ruin an entire roof. This is not the most difficult task at hand, but it is very important to get it right. First make sure you get the right supplies as the flashing metal must come in an appropriate size. Typically there are two ways of acquiring flashing overlapping and soldering. Soldering is the most difficult one to properly get it right. It is usually used for chimneys and low slopes. Get those corners right and make sure that no water can leak from the chimney. If by any chance a contractor puts a strong emphasis on the underlayment you should have all the alarm bells ringing. A good roof may actually require no underlayment at all. It is a sign that the builder is not very confident in its own work and thus neither should you. So please make sure that the overlapping is positive and that soldering jobs are done with the thermal contraction and expansion in mind. This also means that you should always do your flashing consistently, meaning that you should use the same metal on all the roof. Stainless steel is I think the best choice that you have available as it is both durable and flexible, if on the other hand you intend to make a DYI job, aluminium might be the right choice as it is very to bend, a warning though aluminium flashing won't last very long.

5)Get the right materials. And by this I mean that all the materials you buy should have just about the same longevity. If you are building a slate roof designed to last 200 years, it is not very wise to use plywood which will last 20 years. If on the other hand you intention to build a roof with small durability as a temporary solution, plywood will do just fine. Nails are also very important. They can be easily overlooked and are seen by the contractors as a mean to cut costs. The problem is that you will get what you pay for. Go the extra mile and buy some decent nails or at least make sure that the contractor does. Remind them gently and they will likely get them right.

6)Get the right tools. I know that this sounds obvious, but I have seen countless situations when the construction of a roof was greatly delayed simply because a crowbar could not be found anywhere around. Before you actually start building make sure that you have the proper tools.

7)When dealing with contractors make sure that everything is specified in the contract. The type of material used down to every single detail, the time required and the payment options. Look carefully before you sign anything. You won't need the help of a lawyer, most likely you will need the help of someone who actually knows something about roofing. This is extremely important as one you sign that contract you engage yourself in a very long and possible hard ride. Be careful and read everything.

8)Stay away from inexperienced contractors. This is critical. Before you actually choose a contractor ask for a portfolio and some proof of their qualification, friends can be priceless as their advice based on experience can help you to quickly locate a good contractor.