When it comes time to install metal roofing there's one basic rule of thumb.

If you can't easily walk on the roof because it's too steep, call a professional contractor. With that rule in mindif you want to have a metal roof but can't afford what the professionals have bid, here's how to do it.

First the proper tools are needed. These include a measuring tape, a chalk line with plenty of chalk, a good drill, a sturdy extension ladder and a safe step ladder, ½ pound of ¼ inch roofing nails, metal roofing screws, metal snips, and to hold the nails and screws a nail bag.

Using the tape measure the roof's height adding the desired overhang, generally two to four inches. Make accurate measurements keeping in mind the handy man's mantra “measure twice, cut once.” Now measure the roof's length and height on both sides to estimate how much metal edging to add. Bring these measurements to a local roofing supply company. They will tell you how much roofing to purchase. Keep in mind that three to six inches of unblocked air flow is needed between layers.

It's best to remove the old roof before laying a metal roof. Remove old shingles with a pitch fork, roofing shovel, or roofing pliers . Then lay down 30 pound tar paper which is the base for the new roof. If there's only one layer of shingles on the old roof, lay down 1”x4”x building length pine wood boards screwed onto the old shingles. Apply metal roof edging once the roof is prepared.

Now it's time to place the metal sheets running from top to bottom rather than side to side. They are screwed into the wood slats, using a screw every two feet on both sides of the sheet. Each sheet must overlap the last. At the edge cut the last metal sheet so it's just past the edge of the roof.

When the sheets are applied to both sides of the roof it's time to apply the metal trim along the sides of the roof at the edge. The trim also goes on the peak, first scoring it in the middle so it can be bent over the peak.

Of course these instructions are useful only for installing the standard type of tin barn roof seen in industrial buildings, garages and the like. Other types of metal roofs require different methods for installation. But those can be tackled equally as well by a do it yourself person who wants to install metal roofing.