How to Install Metal Roofing
Time Required: Over 1 day
If you are looking to update your current roof, metal roofing can be an attractive upgrade to standard asphalt shingles. Metal roofing will not only conserve energy, but many metal types can withstand the elements for many years. While the installation process can be completed as an advanced DIY project, it is complicated and can vary slightly based on the brand of panels or shingles that you select. We recommend that you complete this project with one or two helpers and fall protection equipment designed for roof work.
This guide will teach you about metal roof types and give you step-by-step instructions on how to install a metal roof.
Things to consider before you begin:
Whether you are looking to install a metal roof on a shed or a house, it's important to know the difference in the various types of metal roofs available. Let's take a look at the most common types of metal roofs for houses.
- Tin: An affordable option and easier to lay than shingles, tin is the most commonly used type of metal roofing. Often the material used is not actually tin, but galvanized steel or aluminum. Although it is durable, it will produce a little noise if rain or wind occur.
- Copper: Often chosen for its aesthetic, copper roofing is also selected because it will not rust or require additional painting. Though it can be costly and a bit harder to install, copper roof panels can withstand severe weather, fire and is lightweight enough that it won’t put a lot of pressure on the structure of your house.
- Aluminum: Lightweight and rustproof, aluminum is a great choice for coastal climates due to its resistance to salt water corrosion. It's important to note that it does need to be painted and can dent easily.
- Steel: Steel roofing can be costly but it is a lifetime investment. Noise is usually not a factor if you are installing a steel roof over asphalt. Galvanized steel, which is created by using a soft layer of zinc to protect the inner layers, is the most common type of steel roofing.
- Zinc: Long-lasting, corrosion-resistant and recyclable, zinc is a softer metal and can be damaged by hail or extreme weather. Because of its higher cost and soft surface, it would make a good choice for a mild climate.
- Corrugated metal roof panels: While they didn’t used to be considered the best metal roofs for houses, corrugated metal panels are gaining popularity due to their strength, energy-efficiency and resistance to corrosion.
- Use measuring tools to find the length and width of the roof from the ground outside.
- Figure out the slope of the roof by setting a carpenter’s level on the underside of one rafter in the attic. Measure the vertical distance (rise) from the 12-inch mark on the level (run) to the underside of the same rafter.
- Slope is calculated as rise over run. For example, if the vertical height was 6 inches, your slope would be 6:12, or 6/12 or 0.5, expressed as a decimal.
- Multiply the area by the slope. The result is the total square footage in your roofing project.
- Order roofing supplies by the square footage and add 10 percent more for waste.
- Be sure to order your roofing screws at the same time as your metal roofing panels so that you’ll match the colors.
Tip: When installing a metal roof, you want to make sure you are starting square.
- Start from the top of the roof and remove the old shingles along with the flashing, underlayment and vents.
- Hammer down any large nails that are exposed by the removal.
- Inspect the underlying roof sheathing for damage and make any needed repairs.
- Install a layer of roofing insulation as recommended by the roofing manufacturer.
- Use 1 1/4-inch nails to cover the outline of the roof with strips of metal eave flashing, also called edging.
- Place corner pieces where panels will meet bends at the edge of the roofing.
- If there are gutters installed on the eaves, the eave flashing should be installed to overhang the lip of the gutter by about 1/2-inch.
- Align the first metal roofing panel so that it overlaps the edging by 1/2 to 3/4 of an inch and is square to the roof line.
- Be sure the larger edge is laid so that the small edge of the next panel will overlap it.
- Install the roofing screws vertically along each rib in the panel. Place the first screw about 7 inches from the bottom and each subsequent screw about 18 to 24 inches apart along the vertical run.
- Secure the screws but do not overtighten. The washer under the screw head should seal to the surface of the panel without bulging or shifting.
- Run a bead of 100 percent silicone sealant along the underside of the short edge of the next panel. Install the panel so that the short lip overlaps the large lip. The silicone will spread and adhere, creating a seal.
- Screw the new panel in place as described.
- Continue adding panels until the roof is covered. You may need to cut panels to fit angles, using a circular saw with a metal-saw blade.
Metal roofing is also available in the form of shingles.
- Lay the starter row of metal shingles at the drip edge and affix to the roof with metal roofing nails.
- Work up from the initial row starting at the lower corner in a diagonal pattern, staggering the shingles to prevent gaps.
- Most metal shingles will be attached to the roof using metal shingle clips, but metal roofing shingle installation can be system specific.
- Consult the guide for your shingle brand to determine the specific method of installation required to preserve the warranty.
A roof vent installation kit will provide everything you need to vent your roof in one convenient package.
- When determining the placement of the roof vents, measure the vent housing and mark off the space on the roof. Allow space for the edge of the vent opening where it will rest on the roof.
- Mark the outline of the roof cuts that will be needed, then use a skill saw to cut the outlined space. You should be able to see the attic interior when done.
- Apply a layer of sealant to the edges of the hole, then place the vent into position.
- Drill starter holes if needed, then scew down the vent with the fasteners in the installation kit.
- Apply a second layer of sealant around the lip of the vent outside. Then move into the attic and apply to the underside of the opening and vent.
- Place the cover over the vent opening and screw into place.
- Flashing is metal trim that fits over joints where two sections of roof meet. It helps direct water away from the meeting points and keeps the roofing dry.
- Bend the flashing into a V-shape to fit over the top roof ridge and the corners where the panels meet.
- The flashing should overlap the edge of the roof by one inch to help direct water.
When learning how to install a metal roof, understanding safety is the most important step. Always be sure to prioritize safety when working above ground.
Gloves and safety googles should be part of your roofing supplies and worn at all times to prevent injury. Always prioritize safety when working above ground.
- Be sure there are no electrical wires or low branches hanging over the roof.
- Secure your ladder at the base and at the point of roof contact. Test the ladder to be certain it will not shift under your weight.
- Use proper fall protection equipment and be certain the system is anchored to your roof studs correctly.
- Wear appropriate safety shoes when engaging in roof work.
While this overview can give you a good idea of what is generally required to install a metal roof, the process can be very complex and hazardous. A project of this scope is often best assigned to a professional installer. If you decide to hire professionals for your metal roof installation, thoroughly research and select a team that has experience in roof repair, the roofing system you want and that is insured (general liability and worker’s compensation insurance) and licensed as required by your state.