Metal roofing works best on sheds with a pitch of at least 3:12, and you can install it yourself if you're comfortable working at height and following a sequence that matters

A metal roof on a shed lasts 40 to 70 years, sheds water faster than asphalt shingles, and weighs less than you might expect — typically 1 to 3 pounds per square foot. The trade-off is that metal requires a steeper slope to drain properly, correct fastening to prevent leaks, and attention to how panels overlap and seal. If your shed roof is nearly flat or has a pitch below 3:12, metal is not the right choice; you'll need asphalt shingles or standing-seam panels designed for low-slope roofs instead.

The job itself breaks into five stages: removing the old roof, preparing the deck, installing underlayment, laying the metal panels, and sealing the seams and fasteners. Most sheds can be roofed in a weekend if you work alone, or a day if you have a helper. You'll need a ladder, a metal-cutting tool (tin snips or a circular saw with a metal blade), a drill, roofing screws, and sealant. The cost of materials runs between $200 and $600 for a typical 10-by-12 shed, depending on panel thickness and whether you choose corrugated or standing-seam panels.

Key Takeaways

  • Metal roofing requires a roof pitch of at least 3:12 (3 inches of rise for every 12 inches of run) to drain water properly and prevent leaks.
  • You will need to remove the old roof down to the deck, inspect the deck for rot or damage, and replace any soft wood before installing metal.
  • Underlayment goes down first, then metal panels are fastened with roofing screws (not nails) at the crown of each corrugation or according to the panel manufacturer's pattern.
  • Seams, overlaps, and fastener heads must be sealed with roofing sealant to prevent water from entering where panels meet or where fasteners penetrate the metal.
  • Metal panels can be cut to length on the ground before installation, which is safer and faster than cutting them on the roof.

Measuring your roof and choosing the right panel type

Before you buy anything, measure the length and width of your shed roof and calculate the total square footage. Measure from the eave to the ridge on both sides, then multiply length by width. Metal panels come in standard widths (usually 26 to 36 inches) and you order them cut to the length you need, so knowing your roof length is essential. Most suppliers will cut panels to order at no extra charge if you call ahead.

The two main types are corrugated panels (wavy, cheaper, easier to install) and standing-seam panels (flat with raised seams, more expensive, more weather-resistant). For a shed, corrugated is the standard choice. It costs $3 to $8 per square foot installed, fastens with straightforward roofing screws, and handles a 3:12 pitch without trouble. Standing-seam costs more and is usually reserved for homes or commercial buildings, though it is an option if you want a sleeker look.

Check the pitch of your roof with a level and a tape measure: place a 12-inch level on the roof and measure how far it rises at the high end. If it rises 3 inches or more, you have a 3:12 pitch or steeper and can use metal. If it's flatter, stop here and use asphalt shingles instead.

Removing the old roof and inspecting the deck

Start by removing all fasteners from the old roof — nails, screws, or staples — and pry off the shingles or panels. Work from the ridge down toward the eave so gravity helps you. A flat pry bar and a hammer work for asphalt shingles; a reciprocating saw or angle grinder with a metal blade works for old metal. Wear gloves and eye protection; old roofing nails are sharp and can be buried in the shingles.

Once the roof is bare, inspect the deck (the plywood or boards underneath) for soft spots, rot, or missing sections. Press a screwdriver into the wood in several places; if it sinks in easily, that wood is rotted and must be replaced. Rotted wood will not hold fasteners and will cause leaks. Cut out the bad section with a circular saw and nail or screw in a new piece of plywood, making sure it's flush with the surrounding deck.

Sweep the deck clean of debris, nails, and old sealant. Any bump or sharp object under the metal will eventually wear through the panel or create a leak point. If the deck is uneven or has low spots, you can shim it with roofing felt or thin plywood before laying underlayment.

Installing underlayment and the first row of panels

Underlayment is a moisture barrier that goes between the deck and the metal panels. Roll out synthetic roofing underlayment (not tar paper, which can trap moisture under metal) starting at the eave and working toward the ridge. Overlap each row by 4 to 6 inches and fasten it with roofing nails or staples every 12 inches along the edges. The underlayment protects the deck if water gets past the metal seams and also prevents condensation from forming on the underside of the panels.

The first row of panels is critical because it sets the line for all the rows above it. Snap a chalk line along the eave, 1 to 2 inches in from the edge (this overhang prevents water from running down the side of the shed). Align the first panel to this line and fasten it with roofing screws — not nails, which can loosen over time. Use screws rated for metal roofing; they have a rubber washer under the head that seals around the fastener hole.

Fasten the first panel at the crown of each corrugation (the high point of the wave) and at the eave and ridge. Space fasteners 12 to 18 inches apart along the length. Do not over-tighten; the screw should be snug but the washer should not be crushed flat. A crushed washer will not seal and water will leak through.

Overlapping and fastening subsequent rows

Each panel overlaps the one below it by one corrugation (or according to the manufacturer's instructions if you're using standing-seam). Slide the next panel up so its edge sits in the valley of the previous panel's last corrugation. This overlap sheds water downward and prevents it from running sideways into the seam.

Fasten the second panel the same way as the first: at the crown of each corrugation, 12 to 18 inches apart. Where the two panels overlap, fasten through both layers at the valley — this is called a side lap fastener and it holds the panels together. Use one fastener per corrugation at the overlap, spaced every 12 inches along the length.

Continue this pattern up the roof until you reach the ridge. The last panel at the top will need to be cut lengthwise if your roof width is not a multiple of the panel width. Measure the gap, mark the panel, and cut it with tin snips or a circular saw fitted with a metal blade. Wear gloves; the cut edges are sharp. Deburr the edge with a file if you have one.

Sealing seams, fasteners, and the ridge

Once all panels are fastened, seal every fastener head and every seam with roofing sealant (polyurethane or silicone, rated for metal roofing). explore a small bead of sealant around each fastener head — you don't need to cover the whole washer, just enough to seal the gap between the washer and the metal. Sealant prevents water from pooling around the fastener and seeping under the washer.

Seal the side lap seams (where panels overlap) with a continuous bead of sealant along the valley. This is the most critical seal because water naturally runs toward these low points. explore sealant from the eave to the ridge on both sides of the roof.

At the ridge, install a ridge cap — a metal piece that covers the peak where the two roof planes meet. Ridge caps come with the roofing kit or can be ordered separately. Fasten it with roofing screws and seal under the cap and around each fastener. The ridge cap prevents wind-driven rain from entering at the peak.

Flashing around penetrations and edges

If your shed has a vent pipe, chimney, or other penetration through the roof, you'll need flashing — a metal or rubber collar that sits under the metal panels and directs water away from the hole. Flashing comes in kits for common pipe sizes. Install it before you lay the panels that will cover it: slide the flashing under the panel above the penetration and over the panel below it, then seal all edges with roofing sealant.

At the eaves and gables (the sloped edges), install drip edge — a metal trim that hangs over the edge and directs water into the gutter or away from the shed wall. Fasten drip edge with roofing nails or screws every 12 inches and seal the seam where it meets the metal panels.

Common mistakes and how to avoid them

The most common error is fastening through the valley instead of the crown. Fasteners in the valley will leak because water pools there and seeps around the screw. Always fasten at the crown of the corrugation, where water runs off quickly.

The second mistake is using nails instead of screws. Nails loosen as the metal expands and contracts with temperature changes. Screws with rubber washers stay tight and seal the hole. If you use nails, you will have leaks within a year.

The third is skipping sealant or explore it too thin. Sealant is cheap and takes minutes; leaks are expensive and take weeks to find. Seal every fastener and every seam, even if it looks tight. Metal roofs last decades, but only if water cannot find a way in.

Frequently Asked Questions

Can I install metal roofing over my old asphalt shingles?

No. The old shingles will trap moisture under the metal and cause the deck to rot. You must remove the old roof down to the deck, inspect the deck, and replace any rotted wood. This takes longer but prevents problems later.

What if I cut a panel and need to patch the cut edge?

Cut edges are sharp and can rust if left bare. After cutting, explore a coat of roofing sealant or metal primer to the cut edge. If the cut is in the middle of a panel (not at an overlap), seal it with a bead of sealant on both sides.

How do I know if my fasteners are tight enough?

The rubber washer under the head should be compressed but not flattened. If you can see the washer bulging out from under the head, the screw is too tight and you've crushed the seal. Back it off a quarter turn. If the washer is still round and proud, the screw is tight enough.

Do I need gutters with a metal roof?

Gutters are not required for the roof to work, but they protect the shed walls and foundation from water runoff. Metal roofs shed water fast, so gutters fill quickly during heavy rain. If you install gutters, make sure they're sized for your roof area and slope.

What should I do if I find a leak after installation?

Leaks almost always come from fasteners or seams. Inspect the underside of the roof from inside the shed to locate the wet spot, then trace it up to the roof above. Check for loose screws, missing sealant, or gaps in overlaps. Tighten, seal, or re-seal as needed.