What Makes It Different
Every metal roof is not the same roof, and the difference is not cosmetic. It is how the panel is held down.
Standing seam — concealed clips
The panel is not screwed down. It is held by clips hidden under the seam, which let it slide as it expands and contracts. A 20-foot steel panel moves measurably between a January night and a July afternoon, and the system is designed around that. Nothing penetrates the weather surface in the field of the roof.
Exposed fastener — screwed through
Screwed through the face into the deck, with a neoprene washer under each head. The panel still wants to move; the screw stops it. Every thermal cycle works the fastener against the washer. That is why it costs roughly half and lasts 25–40 years against 40–60.
The seam itself stands proud of the water plane, which is the whole idea in the name: the joint between panels sits above where water runs rather than in it.
Exposed-fastener panel is a sound choice on an unheated barn and a poor one over finished, heated space. It is cheaper for a reason, and in this climate the reason shows.
What Goes on the Quote
| Item | What to look for |
|---|---|
| Panel material | Galvalume steel for most houses; aluminium near salt or heavy road-salt spray; copper where budget and architecture warrant it. |
| Gauge | Lower number is thicker. Thicker resists oil-canning and denting better and costs more. It should be stated, not implied. |
| Seam profile and pan width | Narrow pans read as residential and period-appropriate; wide pans read agricultural. On a historic house this is the decision that matters most visually. |
| Finish system | There is a real difference between coating systems in how they hold colour. Ask which, and ask what the finish warranty covers separately from the panel. |
| Clip type and spacing | Fixed or floating, and at what centres. On long panel runs floating clips matter. |
| Underlayment | High-temperature synthetic under metal, plus ice-and-water membrane at eaves and valleys — not optional in this climate. |
| Panel forming | Roll-formed on site to exact length, or factory panels trucked in. Site forming avoids transverse seams; some lots have no room for the machine. |
| Snow retention | Where, and what type. $1–$3 per square foot of protected area. |
| Deck repair rate | Agreed before tear-off. On an older roof something is usually found. |
New Hampshire Numbers
| Material | Per sq ft installed | Typical 1,600 sq ft roof |
|---|---|---|
| Galvalume standing seam | $12–$16 | $19,200–$25,600 |
| Aluminium standing seam | $14–$20 | $22,400–$32,000 |
| Copper standing seam | $25–$40 | $40,000–$64,000 |
| Snow retention, added | $1–$3 | — |
Where you land in those bands is decided by complexity rather than size. Valleys, dormers, hips, chimneys, stacks and the junctions of connected ells are where the labour and flashing are. And roof area is not footprint — multiply by roughly 1.06 for a shallow pitch, 1.25 for a moderate one, 1.45 for a steep one.
- Priced off the actual roof form, not the footprint
- Concealed-clip system so panels move with temperature
- High-temperature underlayment, ice-and-water at eaves and valleys
- Snow retention designed for where a slide would actually land
- Deck condition assessed and the repair rate agreed before tear-off
- Panel profile and finish shown against your own house before you commit
Questions
Is it noisy in the rain?
Not over a solid deck with underlayment and an insulated assembly beneath it, which is how a house roof is built. The noise people remember is from panel screwed to open purlins over an uninsulated barn — nothing between the metal and the space below. A house roof is a completely different construction.
What is oil-canning, and should I worry?
The slight waviness visible in flat metal panels at certain angles and light. It is an aesthetic characteristic of the material, not a defect, and it does not affect performance. Heavier gauge, narrower pans and striations or ribs in the pan all reduce it. Ask to see a panel in daylight rather than a brochure photograph.
How long does installation take?
A straightforward house roof is typically a few days to a week depending on size, complexity and weather. Complex roofs with a lot of flashing take longer, and site-forming panels adds a day of setup. Weather governs more than anything — nobody should be installing metal panels in high wind.
Can solar panels go on it later?
Yes, and standing seam is the best possible roof for it. Clamps attach to the seams themselves with no penetrations at all, which is not true of any other roofing material. If solar is anywhere in your plans, that is a genuine argument for doing the roof in standing seam first.
What maintenance does it need?
Very little, though not none. Keep valleys and gutters clear of debris, check flashing and sealant at penetrations every few years, and look at the snow retention after a heavy winter. The things that fail on a metal roof are almost always the details rather than the panels.