Metal roofing
Metal is a detailing trade, not a material choice
A metal roof that is installed properly outlasts two or three shingle roofs. A metal roof that is installed like a shingle roof leaks at every penetration within a few years.
The two systems, and what separates them
| Consideration | Standing seam | Exposed fastener |
|---|---|---|
| How panels are fixed | Concealed clips, no penetrations through the water plane in the field | Screws through the panel face with a rubber washer |
| Thermal movement | Clips allow panels to move as they expand and contract | Movement works against a fixed screw, which eventually elongates the hole |
| Maintenance | Almost none in the field; attention goes to flashings and penetrations | Washers harden and need checking; some screws need replacing over the life of the roof |
| Where it fits here | Main roof planes on houses, and anywhere the roof is visible | Outbuildings, barns, porch roofs, and budgets where the trade-off is understood |
| What it asks of the installer | Accurate layout, correct clip spacing, and flashings fabricated rather than bought off a shelf | Correct screw torque, which sounds trivial and is not |
Where metal genuinely makes sense on a Cincinnati house
- Low-slope sections that shingles cannot cover. Porch roofs, additions and dormer tops below the minimum slope for asphalt. This is the most common good reason for metal on an otherwise shingled house.
- Complicated historic rooflines where standing seam was the original material and a shingled version looks wrong and details badly.
- Long, simple slopes where a standing seam system can run unbroken from ridge to eave with no penetrations to work around.
- Houses where snow shedding is wanted, with the important caveat that shedding snow has to go somewhere that is not a doorway or a driveway.
What decides whether it performs
Almost everything that goes wrong with a residential metal roof happens where the metal stops: at the eave, at a wall, at a chimney, at a valley, or at a pipe. Panels in the field of the roof rarely fail. Fabricated flashings, correct clip spacing, allowance for movement, and a plan for every penetration are what the job actually consists of.
Ask to see how the installer intends to detail the valleys and the wall junctions before anything is ordered. If the answer involves sealant as the primary defense rather than as a backup, that is the answer.
The honest trade-offs
- Metal is noisier in rain than shingles over a solid deck, and noticeably so over an open framed porch.
- Oil-canning — slight waviness in flat panel areas — is a characteristic of the material, not a defect. Striations and heavier gauges reduce it and do not eliminate it.
- Walking on a finished metal roof requires knowing where to step. Anyone who works on the roof afterwards, from a satellite installer to a chimney sweep, needs to know that.
- A metal roof is a long commitment. If the house is likely to change hands in a few years, the value of that longevity does not all come back to you.
Considering metal for a porch, an addition or the whole house?
Request a free inspectionCan metal go over my existing shingles?
It is sometimes done over purlins. It is still hiding a deck nobody has looked at, and it makes any future work on the structure harder. Where a metal roof is worth doing, it is worth doing on a deck that has been seen.
Does a metal roof attract lightning?
No. It is not more likely to be struck, and because it is non-combustible and conductive it is generally considered a safer covering in a strike than a combustible one.
Will it dent in hail?
Softer metals and lighter gauges can dent in large hail. Given that this market records far more damaging wind than hail, denting is usually a smaller consideration here than wind performance, where metal does well.
All work is performed by licensed and insured local roofing professionals.