The short answer
Standing seam hides its fasteners under raised seams so nothing penetrates the water plane, lasting 40 to 50 years with minimal maintenance. Exposed fastener panels screw through the face, cost far less, and need re-screwing every 10 to 15 years as the washers fail. Use standing seam over living space and exposed fastener on barns and shops.
Side by side
| Factor | Exposed fastener (R-panel) | Standing seam |
|---|---|---|
| Fasteners | Through the panel face | Concealed under seams |
| Service life | 20 to 30 years with maintenance | 40 to 50 years plus |
| Maintenance | Re-screw at 10 to 15 years | Essentially none |
| Leak risk | At every screw | Very low |
| Thermal movement | Wallows out screw holes | Clips allow free movement |
| Relative cost | Lowest metal option | Roughly 1.5 to 2 times more |
| Solar mounting | Requires penetrations | Clamp on, no penetrations |
Choose Exposed fastener (R-panel) if
- You are roofing a barn, shop, equipment cover or well house
- The structure is unconditioned and a little condensation on a concrete floor does not matter
- Budget is the dominant constraint on a secondary structure
- You accept re-screwing as a scheduled maintenance item
Choose Standing seam if
- It is over living space of any kind, including a barndominium
- You want a roof you never think about again
- You are collecting rainwater off it
- Solar is planned, since clamp on mounts avoid roof penetrations entirely
- The property is exposed to ridgeline wind
What this looks like in the Hill Country
Around Spring Branch, Canyon Lake and the Kerrville acreage, we see a lot of ten year old exposed fastener roofs that are dripping at dozens of points. The panels are usually fine. The washers are done. That roof does not need replacing, it needs re-screwing, which is a fraction of the cost. Ask about that before accepting a tear-off quote.
