How to Repair a Flat Metal Roof Leak

What You'll Need
Roofing cement
Wire brush
Tin snips
Soldering iron
Safety glasses

However good a flat metal roof might be, it’s still liable to leaks as water can pool on it and cause rust that eventually forms a hole. When this happens you’ll need to fix the leak quickly. It’s not a difficult job, one even those without any construction experience can manage without a problem.

Step 1 - Metal

After establishing exactly where the leak is on the metal roof and how large it is, you need to discover what type of metal the roof is made from. You’ll need to match this in order for the metal patch you create to join on properly.

Step 2 - Cleaning

Use the all purpose cleaner on the area around the leak. This will take off the dirt so your patch can adhere fully without coming off later. When you’ve done that, use a wire brush on the area to clean more deeply all remove any last vestiges of dirt.

Step 3 - Patch

Your metal patch needs to be 2 inches larger in all directions that the leaking area. Having cut it, making sure it’s square, take your tin snips and cut in diagonally at each corner, making the cut about ½ inch in length. This will make it easier to fold the edges of the patch.

Now, with the pliers, fold over all the edges and press them down so they’re firm against the rest of the patch. Take your sandpaper and rub the edges you’ve just folder. They need to be brighter than the rest of the metal on the patch.

Step 4 - Solder

Apply a bead of flux both to the edge of the patch, where you’ve just sandpapered it, and also where the patch will lay on the flat metal roof. Now lay the patch in place and weight it down. A heavy stone is good for this.

Heat up the soldering iron and apply it where the patch meets the roof. Have your solder there, so the heat melts the solder and forms a bond between the roof and the patch. Go all the way around the patch, being sure that you don’t leave any spaces, no matter how small. Remove the stone.

Step 5 - Security

Cut 2 more metal patches, both of them bigger than the patch you’ve just soldered in place. To apply them, first put roofing cement on the area so it covers the same area as the patch you’ve just cut. Put the first of the new metal patches in place, pressing it down firmly so every part of it sticks.

Once you’ve done that, apply more roofing cement on top and stick the second patch on top of the first. Weigh it down, using the stone once more. After they’ve had a chance to dry, complete the job by coating with one final layer of roofing cement and your leak will be fixed.