Metal Roof Installation Cost Calculator

There are two metal roofs, and they are not grades of the same thing

Almost every confusing metal roofing quote comes from this. "Metal roof" describes two systems that share a material and nothing else that matters:

Both are real products and the cheap one is not a scam. But the difference is not finish quality — it is whether the roof has holes in it.

Every screw is a consumable

An exposed fastener roof is held down by screws driven through the panel, each with a bonded rubber washer that makes the seal. There is roughly one screw every two square feet, so about 1,500 of them on an 1,800 sq ft roof.

Rubber in sunlight has a life. Those washers harden, shrink and crack somewhere between 10 and 20 years in, and then each one is a small hole in your roof. The remedy is a re-screw: every fastener removed and replaced, usually with a slightly larger screw because the hole has grown. That is a real job with a real price — budget something in the region of $1 to $2 a square foot when it comes due, and expect to do it at least once in the roof's life.

The mechanism behind it is worth understanding, because it is the same one that explains the whole price gap.

Metal moves, and that is the entire design problem

A 40 foot steel panel is about half an inch longer on a July afternoon than on a January night. Every day it expands and contracts, and over decades that is tens of thousands of cycles.

• Standing seam fixes the panel with clips that let it slide. The seam holds two panels together while both move, and the fixings are above the water line and out of the weather. Nothing is being worked loose.
• Exposed fastener pins the panel at every screw. The metal still wants to move, so instead the hole slowly wallows — the screw slot grows, the washer loses contact, and the fastener works loose. This is why exposed fastener roofs leak at screws rather than at seams.

So the premium you pay for standing seam is not for a thicker panel or a better paint system, although you usually get both. It is for a roof that accommodates its own movement.

Oil canning, before somebody tells you it is a defect

Flat metal pans show slight waviness in raking light. It is called oil canning, it is inherent to the product, and it is specifically excluded from essentially every manufacturer's warranty.

It is not poor workmanship, and no installer can eliminate it. What reduces it:

• Striations or pencil ribs in the pan — light embossed lines that stiffen the panel and break up the reflection. The single most effective measure, and usually free to specify.
• Heavier gauge. 24 gauge oil cans noticeably less than 26, and both much less than 29.
• A flat substrate. Metal telegraphs whatever it is lying on, so a wavy deck gives a wavy roof. This is a reason to insist the decking is checked and corrected during tear-off.
• Narrower panels. 16 inch pans show less than 18 or 20 inch.
• A matte or low-gloss finish, which reflects less sharply.

Have this conversation before the order goes in, not after the roof is on. Specify striations unless you have seen a smooth-pan roof you were happy with in person.

Gauge, and why 29 is not a bargain

Gauge counts down — a smaller number is thicker metal.

• 29 gauge is the thinnest common residential panel, used on most exposed fastener roofs. It dents from hail and from a dropped tool, and it oil cans badly.
• 26 gauge is a reasonable middle, and a sensible upgrade on an exposed fastener roof.
• 24 gauge is the standard for residential standing seam and what you should assume a standing seam quote means. If a standing seam quote is cheaper than the others, check the gauge first.

Also ask about the paint system. Kynar 500 or Hylar 5000 — both PVDF coatings — hold color for decades. SMP, the cheaper polyester finish, chalks and fades noticeably faster, especially in dark and in red. A PVDF finish is typically 10 to 20% more on the panel and is the cheapest long-term upgrade available on a metal roof.

What you are paying for

For an 1,800 sq ft standing seam roof, walkable pitch, single story, at $24,150:

Two things to notice. The labor is roughly double an asphalt roof of the same size, because panels are measured and cut to the roof, every clip is placed, the seams are closed, and the valley and sidewall flashings are fabricated on site rather than bought in a box.

And the trim line is where quotes diverge most. Trim scales with edges, valleys and penetrations rather than with area, so a cut-up roof needs much more of it than a simple gable. A quote that looks $3,000 cheaper than the others is often a quote with less trim and more sealant in it, and sealant is a maintenance item where a flashing is not.

The fifty-year arithmetic, honestly

Metal roofing is usually sold on payback. Here is the sum on this roof, in today's money:

So on replacement cycles alone, metal does not pay for itself. It is roughly $8,750 more over fifty years, and anyone telling you otherwise is either assuming asphalt prices rise faster than metal prices or is selling metal.

What actually makes the case, and it is a real case:

• Once and done. One tear-off, one disruption, one dumpster in the driveway, and no re-roofing decision in your sixties.
• Hail and wind. A Class 4 impact-rated metal roof earns a meaningful insurance discount in hail states — commonly 10 to 30% off the wind-and-hail portion of the premium, which compounds over decades. Ask your insurer for the actual figure before you buy, because it varies enormously and in some states it is nothing.
• Fire. Non-combustible, which matters in wildfire country and sometimes in the premium too.
• Resale. Metal reads as a done roof to a buyer, where a 15-year-old asphalt roof is a negotiating item.
• Solar. Standing seam is the best substrate there is for panels — S-5 type clamps grip the seam with no penetrations at all, so there are no roof holes and no flashing to fail. If solar is anywhere in the plan, this is worth real money and is a genuine reason to choose standing seam over everything else.
• Energy, modestly. A reflective finish cuts cooling load in hot climates. Real, but usually a few percent of a cooling bill rather than the transformation it is sometimes sold as.

Decide on those rather than on payback, and the decision gets much easier.

Two things people worry about that are not real

• Noise. A metal roof over solid decking with underlayment is not noticeably louder in rain than asphalt. The reputation comes from barns and porches where panels are screwed to open purlins with nothing behind them. If anything, the underlayment and the airspace damp it.
• Lightning. Metal does not attract lightning. It is not more likely to be struck than any other roof, and being non-combustible and conductive it is arguably the safer outcome if it is. This has been studied; the concern is folklore.

Three things that are real

• Condensation. This is the genuine metal-specific risk. Metal gets cold, and moist air from inside the house meeting a cold underside condenses on it. In a vented attic with good intake and exhaust, and with the right underlayment, this is a non-issue. In an unvented or poorly vented assembly — a cathedral ceiling, a converted attic, a tight house with bathroom fans venting into the roof space — it can soak the insulation and rot the deck. If your roof is not a conventional vented attic, this question needs answering before the panels arrive, usually with a vented batten system or closed-cell insulation under the deck.
• Snow slides off in sheets. That is often good, but a slab of snow landing on a doorway, a walkway, a parked car or a gas meter is not. Snow guards or a snow rail above those spots are cheap at installation and awkward afterwards. Point out every door and path on the plan.
• You cannot casually walk it. Standing seam is walked carefully, in the right places, in soft shoes. Anything that gets mounted later — satellite dish, antenna, solar — needs seam clamps rather than screws, and a roofer rather than the installer of whatever it is. Decide about penetrations now.

Can it go over the existing roof?

Sometimes, and it saves the tear-off line in the table above — but it is a worse roof.

• Check the code and the layer count. Most jurisdictions allow a maximum of two roof coverings; if there are already two layers, there is no choice.
• The deck cannot be inspected. Going over the old roof means nobody looks at the sheathing, so soft spots, old leaks and failing nailers stay where they are under a fifty-year roof. This is the real argument against it.
• Furring or a slip sheet is needed. Metal laid directly on asphalt shingles abrades on the granules as it moves. It needs battens or a proper separation layer, which gives back some of the saving.
• Ventilation changes, and the condensation question above gets harder.

On a roof you intend to be the last one, pay for the tear-off and have the deck looked at.

Questions worth asking

• Standing seam or exposed fastener, and what is the gauge?
• Is it a PVDF finish — Kynar or Hylar — or SMP?
• Are the panels striated, and what width are the pans?
• Mechanically seamed or snap-lock? Mechanically seamed is better on low pitches and in high wind.
• What is the minimum pitch this system is rated for? Snap-lock systems usually want 3/12 or more.
• What underlayment, and is it high-temperature rated?
• Is the trim in the panel finish, and is it fabricated or stock?
• Is there an ice barrier at the eaves and in the valleys?
• How is the deck being checked, and is decking replacement an allowance or a line?
• Snow guards above which doors and paths?
• Is the attic ventilation being assessed as part of this?
• What is the warranty on the finish, as distinct from the panel, and is the workmanship warranty separate?