The Complete Guide to Metal Roofing Installation

How is a metal roof installed?

The old covering comes off or is prepared to be built over, the deck is checked, underlayment goes down, flashing and trim are set at the edges and penetrations, and panels run from ridge to eave. On a standing seam roof the seams are then closed, by hand or by machine.

Get Metal Roof Cost Guide connects you with licensed local companies. We are not a roofing contractor and do not perform the work ourselves.

What are the parts of a metal roof called?

Knowing the vocabulary changes what you can ask about, and most of the components that decide whether a roof lasts are ones you will never see again once the job is finished.

What does the sequence on site look like?

A metal roof is a layered system installed in a fixed order, and each layer depends on the one under it being right. If you want to know whether a crew is thorough, watch what happens before any metal appears.

• Tear-off of the existing covering, or preparation to install over it
• Deck inspection, and repair of anything soft or damaged
• Underlayment across the deck, with attention at valleys and eaves
• Eave, rake and valley flashing set before panels
• Panels set in sequence, fixed with clips or through fasteners
• Seams closed, mechanically seamed on site where specified
• Penetrations flashed and sealed individually
• Ridge cap and ventilation completed
• Trim finished, and the site cleared of offcuts and fixings

Clearing up matters more than it sounds. Metal offcuts and screws left in a yard are a hazard, and a magnetic sweep at the end is a sign of a careful crew.

Why does underlayment matter so much?

Because it is the layer that actually keeps water out when something else fails, and because it is the only part of the system you can never inspect or upgrade again without taking the roof off.

A roof intended to last decades sitting on underlayment chosen to save money on quote day is a false economy of a particularly annoying kind. If a quote is cheaper than the others, this is one of the first places to look for the difference.

What is oil canning, and is it a defect?

Oil canning is the visible waviness that can appear in the flat area of a metal panel. It is an inherent characteristic of light gauge metal rather than a structural fault, and it does not affect how the roof performs.

It can be reduced by heavier gauge material, striations or ribs rolled into the panel, and careful handling and installation. Most manufacturers exclude it from warranty cover precisely because it is cosmetic and inherent, so if appearance matters to you, raise it before the order rather than after.

What should be written into the quote?

Ask for a specification rather than a price. It is what makes quotes comparable, and it is what you hold a company to if the finished roof is not what was described.

• Panel system and profile, and the seam type if standing seam
• Metal, gauge and coating or finish system
• Underlayment type and where it is applied
• Whether tear-off is included, and disposal with it
• What happens if the deck is found to be unsound
• Flashing details at valleys, penetrations and walls
• Ventilation, at ridge and at intake
• Snow guards, if the roof and location call for them
• Warranty terms, separating material from workmanship
• Who pulls the permit

Guides on this topic

Frequently asked questions