Patching a Metal Roof

Unlike the main roof that just needed scraping and painting, parts of the porch's metal roof had rusted through (Photo A). A new roof would have cost two to three times as much as repairing the current roof using Preservation Product's Reinforced Restoration System (see below).

The first step was to scrape the roof to remove any loose paint, roof cement [Roof cement should never be used on a terne metal roof], and loose rust (Photo B). A metal putty knife was used, carefully.

After the scraping, the roof was power washed and a strong solution of TSP brushed on. This TSP solution was then removed using a power washer. A chlorine solution was then washed on to remove any remaining moss, mildew, and algae. A hose with a nozzle probably would have worked as well as the power washer since the scraping and TSP solution took off all of the loose material. Power washing was limited to where there were no holes in the metal. I also used a sander.

The Preservation Product's restoration system required the following steps:

  • (1) A rust inhibitive primer coating was painted on using both a brush and roller (See below).
  • (2) Small sections of each roof panel were coated with an acrylic coating and a high strength stitch-bonded reinforcement fabric was embedded into this wet coating, Photo C. The fabric panels were cut to fit each section although the fabric come's in two sizes: One to go in between the roof panels and another size to go over the metal seams. If it is hot, large pieces of the fabric cannot be applied in the sun as the coating that the fabric is embedded into dries too quickly.
  • Two coats of a high strength waterborne elastomeric finish coating were applied on top.

In some places, the two inch metal overhang had rusted away. In these cases, pieces of fabric were dipped into the coating liquid and then draped over the edge to fill in the missing metal, Photo D.

Product Information

Preservation Productsleave site

Information on tin roof repair from a roofing firmleave site

Rust Converters

Study comparing rust convertersleave site

Rust-Oleum Rust Reformerleave site (Selected as the top performer in the study above)

Help support this site


Link to Amazon from here

Roof rusted through on an old house. DYI how to repair.

A. Roof had rusted through.

B. Roof was scraped.

C. Fabric reinforcement applied.

D. Where metal had rusted away, created an overhang using impregnated cloth .