Metal roof crisis: Restoration vs. TPO overlay
When dealing with a metal roof on purlins, you have two primary professional paths: Fluid-Applied Restoration or a TPO Overlay with Flute Fillers.
1. Fluid-Applied Restoration: The "Active" Defense
- The Rust Factor: Restoration actively treats corrosion. It uses specialized rust-inhibitive primers that chemically convert or encapsulate oxidation.
- The Process: Seams and fasteners are reinforced with mastics, and the surface is encased in a seamless membrane.
- Pros: Stops corrosion, lightweight, and has a 20-year renewable warranty (re-coat at year 20 to reset the clock).
2. TPO Overlay with Flute Filler: The "Cap" System
- The Warranty: Standard commercial TPO warranties typically cap at 20 years.
- The Insulation Factor: Provides a R-value boost and reduces interior condensation.
- Pros: Thermal barrier and aesthetic upgrade.
- Cons: Can trap oxidation (the “Greenhouse Effect”) and add significant “dead load” weight to purlins.
The "Save vs. Scrap" Checklist
1. The "Hammer Test" for Surface Rust
- Restoration Candidate: Rust is orange/red but metal is rigid and sounds solid when tapped.
- TPO Candidate: Metal flakes or is easily punctured. Structural integrity is gone.
2. Fastener & Seam Integrity
- Restoration Candidate: Fasteners are mostly tight; others can be capped with mastic.
- TPO Candidate: Fastener holes are “wallowed out” or seams are gapped beyond liquid sealant reach.
3. Interior Insulation Condition
- Restoration Candidate: Interior insulation is dry.
- TPO Candidate: Insulation is sagging, shredded, or water-logged.
Head-to-Head Comparison
- Rust Treatment: Restoration (Active: Primers stop rust) vs TPO (Passive: Covers rust)
- Warranty: Restoration (20 Years Renewable) vs TPO (20 Years Replacement)
- Efficiency: Restoration (High Reflectivity) vs TPO (High Reflectivity and some R-Value)
- End of Life: Restoration (Simple Re-Coat) vs TPO (Tear Off)
- Structural: Restoration (Preserves Panels) vs TPO (Adds weight)
- Tax Incentive: Restoration (Considered Maintenance) vs TPO (Amortized)
