In this article 14 sections
- What Are Your Options for an Old Metal Building Roof?
- Restore vs Retrofit vs Replace
- How a Metal Retrofit Works
- Common retrofit framing systems
- Panel Choices for the New Roof
- Stopping Condensation Drips in a Metal Building
- San Antonio Factors
- FAQs | Metal Building Roofs
- Can a metal building roof be replaced while the building is in use?
- How do I know if my metal building can handle a retrofit?
- Should I replace skylights when re-roofing?
- Does a new metal roof need insulation?
- Can I put a membrane roof over my metal roof?
- Get Your Metal Building Options Priced
What Are Your Options for an Old Metal Building Roof?
San Antonio has thousands of pre-engineered metal buildings from the 1970s to the 2000s, and most are reaching the point where screws, laps and skylights leak. Here’s how we choose between the options for commercial roofing in San Antonio.
Restore vs Retrofit vs Replace
| Restore | Retrofit (over existing) | Tear off and replace | |
|---|---|---|---|
| Cost / sq ft | $3 – $9 | Priced per project; no tear-off | about $8 – $13 for old metal |
| Added life | 10 – 20 years | New roof life (standing seam 40 – 70 yrs) | New roof life |
| Building stays in use | Yes | Yes, stays dry | Mostly, with phasing |
| Adds insulation | No | Yes, between old and new roofs | Yes |
| Structure check | Minimal | Required (added weight) | Purlins inspected during tear-off |
| Best when | Panels solid, leaks at screws and laps | Panels worn, building occupied, want insulation | Rust-through or structural damage |
Core Commercial Roofing (2026); BuilderMuse (Jul 2026); Roof Hugger via Roofers Coffee Shop. Tear-off on metal can drop to about $0.40 – $0.75 / sq ft when scrap value offsets disposal.
How a Metal Retrofit Works
- Structural review confirms the frame can carry the added weight.
- Sub-purlins or retrofit framing are fastened through the old panels into the existing purlins.
- Insulation is laid between the old roof and the new one.
- New panels (usually standing seam) are installed on the new framing.
- Trim, gutters and penetrations are rebuilt to fit the new roof height.
A retrofit can also change the roof’s slope or switch from metal to a single-ply membrane, which is useful when the old slope is very low.
Common retrofit framing systems
| System | How it works | Best for |
|---|---|---|
| Panels fastened directly over existing | New panels sit on the old ribs with spacers | Sound roofs, minimal insulation added |
| Notched sub-purlins | Z or hat sections notched over old ribs, fastened to existing purlins | Adding insulation; most common |
| Grid system | Adjustable framing grid over the old roof | Thicker insulation or uneven roofs |
| New framed roof | Light-gauge framing builds a new slope | Changing a near-flat roof to a steeper slope |
Retrofit system types: MBCI, Five Retrofit Choices Using Metal Roofing Systems.
Panel Choices for the New Roof
| Panel | Cost / sq ft | Notes |
|---|---|---|
| Standing seam | $8.64 – $15.35 (San Antonio) | Concealed clips, low leak risk, 40 – 70 years |
| Exposed fastener (R-panel, PBR) | $8.25 – $13.75 (national commercial) | Lower cost; screws need maintenance |
Commercial Roof Guide (Mar 2026); Roof Observations (Jan 2026).
Compare panel types in standing seam metal roofing, and see metal building roofing and commercial metal roofing in San Antonio.
Stopping Condensation Drips in a Metal Building
If your metal building “rains” inside on cool, humid mornings, the panels are reaching the dew point. Re-roofing is the best time to fix it:
- Add continuous insulation in the retrofit cavity
- Install a sealed vapor retarder on the warm (interior) side
- Improve ventilation and control indoor moisture sources
- For existing roofs, an anti-condensation coating on the underside can reduce drips
San Antonio Factors
- Wind: new roofs must meet the city’s wind-uplift requirements (design wind speed about 123 mph).
- Hail: heavier gauges and impact-rated panels resist denting better.
- Heat: PVDF finishes and added insulation cut heat gain in summer.
- Permits: retrofits and replacements need a building permit in San Antonio.
FAQs | Metal Building Roofs
Can a metal building roof be replaced while the building is in use?
Yes. A retrofit keeps the old roof in place, so the building stays dry. Tear-off is done in sections that are closed up the same day.
How do I know if my metal building can handle a retrofit?
A structural review of the frame and purlins checks the added weight. Many buildings handle it easily, but older or lightly built ones may need reinforcement.
Should I replace skylights when re-roofing?
Usually yes. Old fiberglass skylight panels are a common leak and fall hazard, and replacing them during the roof project is cheaper than later.
Does a new metal roof need insulation?
When you replace the roof, the energy code may require insulation. A retrofit makes it easy to add a thick layer between roofs.
Can I put a membrane roof over my metal roof?
Yes. Flute filler, insulation and a single-ply membrane such as TPO can go over a low-slope metal roof, which is common on very flat metal buildings.
Get Your Metal Building Options Priced
We’ll inspect panels, fasteners and structure, and price restore, retrofit and replace side by side.
- Free roof assessment across San Antonio, including Westover Hills, metal roofing in Schertz, Selma and Converse
Book your free roof inspection in San Antonio or see metal roof repair and restoration.
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Questions get answered by the roofers who wrote the article, not a chatbot.