How to Repair a Hole in a Metal Roof System

How to Repair a Hole in a Metal Roof

1. Clean the Repair Area

   Clean the surface of the metal panel thoroughly using Simple Green or another cleaner until the surface of the roof panels is entirely free of any dirt, film, and algae growth. Wipe away any cleaner residue with a wet cloth.

2. Scuff the Metal

   Use a wire brush to scuff the surface where the repair will be made. Scuffing will help the sealant bond to the metal. Use the wire brush only in the area to be patched; wire brushing beyond that may remove the protective coating from the metal panel surface, causing later deterioration.

3. Measure the Repair Area and Cut a Patch

   • Cut the chosen sheet metal to a size that matches the area to be patched. The sheet metal patch should overlap with the metal panel at least 2 inches past the edges of the damaged area.
   • After the sheet metal patch has been cut and fit to size, round the corners of the patch with a file or emery cloth to prevent any sharp corners from becoming a catching spot for snow or ice.
   • Place the patch over the hole being repaired. Outline the patch in pencil onto the roofing.
   • Remove the patch and measure the outline to make sure the patch will overlap by at least 2 inches in all directions past the edges of the damaged area.

4. Install the Repair Patch

   • Apply a color-matched urethane sealant to the surface of the metal panel with the hole, staying just inside the marked pencil line. Apply the sealant liberally in the area so that there are no gaps or voids at the leading edge of the patch.
   • Press the patch into place over the damaged area. The sealant should squeeze out from the edge of the patch along all sides.

   Tip

   If there are areas where the sealant is not oozing, these are areas where moisture may later penetrate under the patch, causing a deterioration of the patch. Apply a little more sealant here to eliminate any gaps.

5. Secure the Patch

   Secure the sealed patch using pan-head sheet metal screws. Space screws every 3 to 4 inches around the patch's perimeter and within 1 inch of the patch's edges so that they apply uniform pressure to the edges and to the sealant beneath the patch.

   The screws should be only long enough to secure the patch to the underlying roofing panel. Never screw the patch down through the roofing panels and into the roof decking or rafters.

   Tip

   After the patch has been attached, retool any sealant bleeding from the edge of the patch using a putty knife. This will ensure that the sealant properly seals the patch's edges and prevents moisture from penetrating. It may take a day or more for the roofing sealant to skin over but up to one week to cure fully.

6. Paint the Patch to Match the Roof (Optional)

   • Confirm that the paint you are using will be compatible with the sealant you used.
   • Wait for the sealant to cure before painting. 
   • Lightly wire-brush the surface of the metal patch and the metal panel just past the patch's edges.
   • Paint over the patch's surface and onto the underlying panel's surface.

Holes in Raised Roofing Seams

If the hole or damage to the roof is in the raised seam between panels rather than in the flat area of a panel, patch it with an asphalt-impregnated glass membrane fabric over the damaged portion of the seam itself.

On raised-seam roofs, the individual panels must be allowed to move along the seams, so never attach a metal patch anchored to both roofing panels over the seam. Instead, repair the damage to the seam with narrow strips of membrane fabric confined to the raised seam section. The patching strip should overlap the damaged area by at least 2 inches.

Apply a coating of urethane sealant over the top of the patching strip, then another patching strip. Done correctly, both roofing panels will still be able to move independently.

When to Call a Professional

Do not attempt on-roof repairs if you are uncomfortable working at heights and on ladders. If there are concerns about completing your roof repair safely, contact a professional roofing contractor who can do the repair for you safely and professionally.

Larger cracks or buckling and wrinkling often require replacement. In these cases, it's best to consult a professional to ensure repairs are completed correctly for the long-term durability of your roof. Most leaks can be located in your attic by finding rafters and joists with water damage, but a professional can also help you find the source of your leak if needed.

Rust is a red flag. It's a sign that your roof is aging and may need a complete overhaul. An expert can evaluate the situation, usually determining how long your roof can last.

The benefit of working with roofing experts is they work on roofs all the time and can finish the job in less time. If you're experiencing a big leak causing damage, instead of spending valuable time researching how to fix the problem, an expert can get it done quickly. Also, the experts are aware of maintaining the roof up to code. Small fixes may seem minor, but they can lead to major headaches if not done correctly.