Sometimes metal roofs can develop holes in them, due to either something falling on the roof and damaging it or from deterioration over time. Whenever a hole develops on your metal roof, it is important to repair the hole promptly.
#1 Clean Around The Damaged Area
First, you need to clean around the damaged area on your roof. You can use simple soap or a product designed specifically for roofs. You want to get rid of any dirt or plant growth around the hole; dirt and plant growth could compromise your patch.
#2 Scuff Up The Damaged Area
Next, you are going to want to take a wire brush and use it to scuff up the surface area the damaged area. Scuffing up the surface will help the patch adhere better to your existing roof surface. It is kind of like sanding wood before you work on it; scuffing up metal will make it easier to repair. Be sure to just scratch the surface though; you don't want to create deep gouges on the roof.
#3 Measure The Damaged Area
Then, take a measuring tape and measure the damaged area. Then, add at least two inches to each side of the measurement. This measurement is the size of the patch that you are going to need to cut out. You want to have extra room to work with so the patch can adhere to your metal roof.
#4 Cut The Patch
Take the measurements you obtained in step three and use it to measure out and cut a patch of sheet metal for your roof. You can cut sheet metal with sheers or a metal saw. When you cut the sheet metal, be sure to round the corners so that the patch doesn't have sharp corners on it.
Put the patch over the damaged area and make sure that it is large enough. If it isn't large enough, you may need to re-cut another patch.
#5 Apply Metal Sealant
Flip the patch over and apply metal sealant to the patch. Put the sealant on the middle of the patch and around the outside edges of the patch where it will meet with your metal roof. It is okay to put a lot of sealant on the patch.
#6 Attach Metal Patch
Finally, take the metal patch and put it over the damaged area. Hold it down and press it into place. Some of the sealant may spill over the edges; that is okay. Then, take some pan-head sheet metal screws and attach them around the perimeters of the patch. Place a screw every few inches, and make sure the screws are not right on the edge of the patch, but at least an inch inward on the patch. This will help keep the patch more secure.
If your roof is painting, you should also paint the patch so that it matches and blends in with the rest of your roof.