Metal Roof Underlayment Solutions for Florida Homes
MRM Tornado Underlayment, engineered for the same climate as the panel above it.
Florida's climate is hard on ordinary roofs, and that includes what's underneath the panel. MRM Tornado Underlayment sits between your deck and your Tornado panel, doing five specific jobs while it's there.
What This Underlayment Does Under a Florida Metal Roof
Class A Fire Rated
Rated for Class A fire resistance as part of a tested roof assembly.
Radiant Energy Barrier
Reflects radiant heat instead of absorbing it, cutting the heat that reaches your attic.
Sound Barrier
Dampens the drumming of rain and hail on a metal roof so the house stays quiet.
Secondary Water Barrier
A self-adhered layer that helps keep water off the deck if the panel above is damaged, until repairs are made.
Self-Adhered Leak Barrier
In Florida the threat is wind-driven rain, not ice. The membrane bonds to the deck and helps seal around fasteners; edges, seams and penetrations are detailed during install.
Where It Goes, and Why That Spot Matters
Installed directly on the plywood roof deck, underneath the MRM Tornado steel or aluminum panel. It's the part of the roof system you never see again once the panel goes on — which is exactly why it has to be right the first time.
Why the Underlayment Matters As Much As the Panel
A metal panel is only as good as what's underneath it. Salt air, summer heat and driving rain all reach the deck eventually — the underlayment is what meets them first.
Felt, Synthetic or Self-Adhered?
Three kinds of underlayment show up under Florida metal roofs. Here's how they differ in practice.
Felt
The traditional, lowest-cost option: asphalt-saturated felt nailed down in overlapping rows. Nail holes aren't sealed, and standard felt can dry out under the heat that builds up beneath a metal panel.
Synthetic
A lightweight woven sheet held with cap nails. It resists tearing better than felt, but it sits on the deck rather than bonding to it, so every fastener hole is still a possible path for water.
Self-adhered
A rubberized membrane that bonds to the deck and seals around the fasteners driven through it. High-temperature versions are built for metal roofs. The MRM Tornado lineup falls in this category.
What “Secondary Water Barrier” Really Means
The metal panel is the primary barrier: it sheds nearly all of the water that hits your roof. The secondary water barrier is the layer underneath that handles what gets past, such as rain driven under a seam, water at a fastener or a leak at a damaged panel.
It works by keeping that water on top of the deck and moving it downslope to the eave. It doesn't replace flashing at walls, valleys and penetrations, and it isn't meant to stay exposed for long, so a damaged panel still needs prompt repair.
The MRM Tornado Underlayment Lineup
Four Tornado underlayment products make up the current lineup.
MRM Tornado Radiant Barrier SWR 5000 FR
Aluminum-foil face for reflective performance, fully self-adhered.
MRM Tornado Radiant Barrier SWR 2000 FR
The lighter-duty companion to the SWR 5000 FR, same reflective aluminum face.
MRM Tornado Duo Barrier 1500 HT
A high-temperature, self-adhered duo-layer barrier built for the deck side of the system.
MRM Tornado White SBS Cap Sheet 4000 FR
Mineral-coated white cap sheet for jobs that call for extra surface durability.
Certifications & Approvals
- Miami-Dade County Approved
- Class A Fire Resistance
- Meets or exceeds ASTM D1970
- Standard 20-Year Limited Warranty
- Manufactured in the USA
- Paired system approval with MRM Tornado Steel & Aluminum Roof Panels (FL-approved)
How Our Metal Roofing Process Works
Free Consultation
We look at your roof, your goals and your budget.
Custom Quote
Clear pricing for the full system, panel and underlayment.
Manufacturing
Panels formed to spec in our Florida facility.
Installation
A licensed crew, a clean job site and a final walkthrough.
Get Your Florida Metal Roof Quote Today
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