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Metal roof repair

A mobile home with a potential leaky roof

If the metal roof on your manufactured home develops a leak, find the source and fix it right away. If you don't, your walls, flooring, insulation, woodwork, doors and windows can become permanently damaged.

Finding the leak can be the most challenging part of the repair. Don't be surprised if a leak in your bathroom originated from a separated roof seam over your living room. When it comes to roof leaks, water does not always travel straight down. It could follow the truss system, it could seep down the sidewalls, or it could pool up in the moisture barrier until it finds an outlet.

To get started, closely inspect your entire roof for possible leaks. Pay particular attention to:

  • The J-rail.
  • The flashing around vents, pipes and skylights.
  • The seams and roof sealant.
  • All existing rumble buttons (don't add anymore!).
  • Any rusted or worn-looking areas.

You should also make sure you have a roof leak and not a condensation problem. If you can't find the leak, you may need to coat the entire roof, which needs to be done every two years anyway. See our article on Coating Your Metal Roof for instructions.

CAUTION! Proceed with Caution When Walking on Metal Roofs

Most makers of manufactured homes say you can walk on your roof, but you should take precautions before climbing onto it. First, inspect your roof and its trusses to make sure they are in sound condition and can safely support your weight. Take extra precautions if the roof is wet, moss-covered, icy or snowy, so you don't slip off.

Whenever possible, make your repairs from a ladder. If you must go up on the roof, watch where you step. If you step in the wrong place, you could pop a seam. Always put your weight on the trusses (rafters) that are usually spaced every 16 or 24 inches. You can also put your weight on the edge of the roof.

Better yet, bring up a large board. The board should be at least ½ inch thick, two feet wide and four feet long. Put your weight on the board to prevent breaking the seal on a seam.

Do not balance the board on the arch of the roof. Instead, place the board so it runs across the rafters. This will help spread your weight. Do not use a board on a steep pitch. It could slide off.

How to Patch a Hole

Materials You'll Need:

  • a piece of galvanized metal
  • sheet metal screws
  • butyl tape
  • roof coating
  • caulk

Tools You'll Need:

  • flexible putty knife
  • tin snips
  • wire brush

Before you patch the hole, carefully inspect the rest of the roof. Especially check all seams, seals and flashings.

If the damaged is extensive, you can make repairs by covering an entire width of the roof. This could be both easier and more effective than installing multiple patches.

Step 1: Clean Area

Remove dirt from the area to be patched. Carefully scrape off any flaking or loose roof coating with a flexible putty knife.

Step 2: Apply Butyl Tape

Put one- or two-inch wide strips of butyl tape around the perimeter of area to be patched.

Step 3: Cut & Cover

Cut a patch out of galvanized metal that will overlap the hole by two to three inches on all sides. Place on top of the butyl tape.

Step 4: Insert Screws

Pre-drill holes in the galvanized metal (both the patch and the roof). Using metal screws, screw through the new patch, butyl tape and existing roof metal. Do not screw into trusses. Make sure the patch is flush with the surface. Start by placing the screws every two inches. If not it's not tight, put a screw every one inch.

Step 5: Seal

Seal around the edges of the patch and the screws with caulk. When that dries, cover with a roof coating.

How to Membrane a Seam

Materials You'll Need:

  • aluminum base roof coating
  • asphalt impregnated, glass membrane fabric roof patch

Tools You'll Need:

  • putty knife
  • paint brush or roller

Use this method of repair to fill in the space created by a parted roof seam, or even a small, narrow crack.

This easy repair is tempting to use on larger holes instead of a metal patch, but, membraning is not recommended for anything but small, narrow holes.

Step 1: Clean Area

Remove dirt from the area to be patched. Carefully scrape off any flaking or loose roof coating with a flexible putty knife.

Step 2: Coat Roof

Cover the area with a good quality, aluminum base roof coating. Make sure you cover both sides of the seam. Do not give the roof coating time to completely solidify.

Step 3: Cover

Use an asphalt impregnated, glass membrane fabric to patch the parted seam. Lay the patch across the seam, on top of the roof coating. The patch must be wider than the seam and it should overlap the parted seam by at least two inches on all sides.

Step 4: Coat Roof Again

Put second layer of roof coating over the patch.

How to Replace an Entire Metal Roof Section

Materials You'll Need:

  • sheet of galvanized metal, longer than the width of your roof
  • butyl tape
  • sheet metal screws
  • roof coating
  • silicone sealant

Tools You'll Need:

  • tin snips
  • flexible putty knife
  • power or standard screwdriver
  • flashlight
  • rubber mallet

If a large area of your galvanized metal roof is damaged, you may want to install a new roof section that's the full width of your home. Overlaying a large roof area is no more difficult than installing several smaller patches.

With damage this extensive, it's important to check the rafters and the area under your roof for damage. Before you overlay your roof, use a flashlight to look for any structural damage and to see if you need to replace the insulation. Remove any standing water and completely dry the attic area before you install the roof section.

Do not screw the roof to the rafters! Your galvanized metal roof is attached to your house only along the perimeter of the house. It needs to be loose everywhere else so it can expand and contract. If your roof already has “rumble buttons,” do not add any more.

Step 1: Loosen J-Rail

Use your power screwdriver to remove the screws along the J-rail on both sides of your roof where you will overlay new material. You do not have to totally remove the J-rail, but it does have to be loose enough so the new metal sheet can slide under it.

Use a flashlight to examine the interior of your roof. Replace any damaged insulation and remove any standing water. Repair or replace any damaged trusses or rafters. Allow the area to dry out before overlaying the roof. If necessary, use tin snips to cut away the damaged roof section to gain access to the attic area. Otherwise, you do not need to remove damaged metal.

Step 2: Cut New Sheet

Make sure the new sheet of galvanized metal is the same length as the damaged piece, but a bit longer than the width of your roof. Also make sure it's at least one foot wider on both sides of the damaged area.

Step 3: Butyl Tape

Apply two-inch butyl tape along the bottom “long” edges of the new sheet metal. You do not need to apply any butyl tape under the width, or short, edges of the sheet metal. These edges slide under the J-rail.

Step 4: Overlay Section

Carefully place the new sheet of metal over the damaged metal. You'll probably need a helper. Make sure this new piece is long enough to fit under the J-rail on both sides.

Slide the edges of the new metal section under the J-rail. Put butyl tape along the edge of the roof, positioned so the J-rail will go on top of the tape. Insert screws through the J-rail, butyl tape, new roof metal and side of house. Do this on both sides of roof. If necessary, purchase longer screws to go through all of these layers.

Step 5: Attach Sides

On top of the roof, insert screws through the new metal sheet, butyl tape and existing metal roof. Do not screw into the roof rafters. Start by spacing the screws every two inches. If needed, space the screws every inch to draw the metal flat to the existing roof.

Step 6: Seal

Seal the edges on all four sides and the seams with a good quality metal roof coating.

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