As always the first step in any roofing application is safety. I Know it gets old to hear, but it could save your life or at least your wallet from those absorbinant medical bills. A 1/4 inch thick metal plate, with eyelets for hooking to, should be screwed to the opposite side of the roof from which you will be working. An approved safety lanyard and properly fitting harness should also be worn. True skipping this step could save time and money, but it could also prove very costly.
First step of the actual process is to prepare the surface. This is easy on new construction, just clear decking of all debris. On older houses it is acceptable to overlay one layer of shingles,providing that you use long enough screws to penetrate metal, shingles and decking. Inch and a half or longer is sufficient. If two or more layers of shingles are present, they will have to be removed. A shingle shovel or “bulldog” is very helpful, some friends with strong backs are even more useful. A large trailer or dumptruck is required for disposal of the old shingles.
Once the shingles are removed and all old nails and debris have been cleared, it is time to begin laying your metal. It is important that you take precise measurements before you order your metal, as it is pre-cut to your desired length. It is pertinent that the first piece you lay be absolutely square as you will gain or lose in eve overhang length if it is not. By placing a string 3″ off of your eve on each end and keeping your metal 1/2″ off your string you can keep your metal running square and neat.
Your metal should be screwed 6″ from the bottom and every three feet after. Keeping the screws straight is important for the looks of the house, so I suggest using a chalkline. The best method is to place screws on ridges, but be careful not to overtighten as this will dent the metal. Screws with neoprene washers should be used and are available anywhere you order your metal. A chalkline should also be used when applying your ridgecap. Rubber fillers are available to fill in the gap between your metal and the cap, however this would cause you to miss out on a unique opportunity for a perfect and very adequate ridge vent. Before the metal is applied, cut a one and a half inch gap on each side of the ridge. Apply aluminum screen down the ridge to keep out the bumblebees. Allow your metal to come to the bottom of this gap. Order your Ridge cap at least 14″ wide. The wide cap costs a little more , but you can save big on your cooling bills. For more information on more complicated applications visit my blog at or check my recent article on premeasuring for and application of valley metal. This can be tricky and costly if done wrong.