How to Install a Metal Roof on an Existing House

When it is time to replace the roof on your home, you may decide you’d like to use a corrugated metal roof instead of shingles.
Installing metal roofing over existing roofing adds insulation.Installing metal roofing over existing roofing adds insulation.
Metal roofing usually costs more, but it will stand up to fire, storms and insects. Such a roof will typically last many years longer than a shingle roof, and many homeowners find that they can do the installation themselves. The end result is well worth the effort involved, and doing it yourself provides not only personal satisfaction but also a substantial cost savings.

Step 1

Wear gloves, eye protection and a safety harness when working on the roof. Brace the ladder carefully and make sure it is solidly placed before attempting to climb onto the roof.

Step 2

Remove the old roofing from the entire surface of the roof, if you are choosing to not cover old shingles. Old shingles can be pried off with a roofing spade and disposed of according to local regulations. Your county may have laws regarding the disposal of old roofing materials, so be sure to check before dumping them.

Step 3

Sweep the surface of the roof so that it is free of any debris. Remove any screws or nails that are sticking up so that the surface is smooth.

Step 4

Unroll an insulated vapor barrier across the roof one section at a time. Be sure the vapor barrier side is against the roof. Nail it in place with galvanized nails. It can either be attached to the roofing deck or to the trusses.

Step 5

Place the closure strips along the eaves and fasten them in place with galvanized nails. Some closure strips have adhesive on them to help hold them in place. Seal the upper edges of the strips with roof caulking to keep moisture out.

Step 6

Lay the corrugated panels in place so that they fit snugly over the closure strips and use screws with attached washers to secure the panels. Start with the row at the lowest level of the roof and complete it before moving to the next row. Overlap the sides of the panels as you place them, applying a line of caulking between them before you fasten each one in place. Also apply caulking between the rows so that water can’t get in around the ends of the panels.

Step 7

Place the ridge panel on the ridge of the roof after all of the metal panels are in place. Apply caulking where it touches the corrugated panels. Use screws with washers to hold the ridge panel in place and complete the roof.

Things You Will Need

  • Gloves
  • Eye protection
  • Safety harness
  • Ladder
  • Roofing spade
  • Broom
  • Insulating vapor barrier
  • Roofing nails
  • Hammer
  • Closure strips
  • Metal roofing screws with nylon washers
  • Metal roofing panels
  • Screwdriver
  • Roof caulking and gun
  • Ridge panel

Tip

  • You may be able to install your new metal roof over the existing roof without removing the shingles. Most building codes allow a new roof to be installed on top of an old one. This results in additional insulating value, as well as a significant savings of cost and labor.

Warning

  • Always use safety gear and never work on a wet or frosty roof. Use gloves and eye protection to further protect you from injury.