If you need help deciding whether you should use the RoofingFoil™ + Underlayment All-in-One product or the RoofingFoil™ Radiant Barrier Single-Sided Solid (Foil Only) product, you're in the right place. 

While both products are designed to reflect radiant heat and improve roofing performance, they are intended for two different types of roofing situations. 

The Biggest Difference: One Is a Complete Underlayment System, the Other Is a Standalone Radiant Barrier

The RoofingFoil™ + Underlayment All-in-One product is a true synthetic roofing underlayment that also functions as a radiant barrier. It is designed to replace a traditional synthetic underlayment while simultaneously adding radiant heat reflection to the roofing assembly.

The RoofingFoil™ Radiant Barrier Single-Sided Solid product is different. It is not intended to function as the primary roofing underlayment layer by itself. Instead, it is a standalone radiant barrier product that is typically paired with an existing waterproof roofing underlayment or installed over existing shingles that remain in good condition.

That distinction is extremely important when evaluating re-roof projects versus full roof replacements.

RoofingFoil™ + Underlayment All-in-One: A Complete Roofing Underlayment System

The All-in-One product was engineered specifically for new roofing installations and full tear-off projects where a complete roofing underlayment is required beneath the finished roofing material.

The product is a 16 mil, 5-layer reinforced assembly consisting of:

• A white non-woven slip-resistant walking surface
• Heavy-duty PE woven reinforcement
• A laminated pure aluminum foil layer

In addition to serving as a radiant barrier, it satisfies the requirements for a synthetic solid roofing underlayment and is Miami-Dade and Florida Building Code approved. 

This means the product is handling multiple jobs simultaneously:

• Secondary water protection
• Vapor barrier performance
• Roof deck protection
• Radiant heat reflection

Rather than installing a conventional synthetic underlayment first and then adding a separate radiant barrier layer above it, the All-in-One product combines both functions into a single integrated system.

This makes it particularly well-suited for:

• Tile roofs
• Standing seam metal roofs
• Stone coated steel roofing
• Batten and counter batten systems
• New construction
• Full tear-off re-roofing projects
• No-tear-off re-roofing projects

RoofingFoil™ Single-Sided Solid: A Dedicated Radiant Barrier Layer

The Single-Sided Solid product takes a different approach.

This product is designed primarily as a radiant barrier layer rather than a complete roofing underlayment system. The material is a durable polyethylene-based reinforced foil product with a pure aluminum reflective surface that reflects 97% of radiant heat when the foil side is installed facing an air gap. 

Because it is intended as a standalone radiant barrier, it is generally installed:

• Over an existing roofing underlayment
• Over existing shingles that are still in good condition
• Beneath battens or furring strips that create the required air space

This makes the Single-Sided product especially attractive for retrofit applications where the homeowner wants radiant barrier performance without performing a full tear-off down to the decking.

In many re-roof situations, the original tar paper or synthetic underlayment may still be intact and functioning properly. In those cases, the existing waterproofing layer can remain in place while the Single-Sided RoofingFoil™ product is added above it before installing the new roofing material.

Both Products Require an Air Gap to Reflect Radiant Heat

Both RoofingFoil™ products require a minimum ½-inch air gap on the foil side in order to function as a radiant barrier. Without that air space, the foil cannot properly reflect radiant heat and instead functions primarily as a vapor barrier only. 

Fortunately, many roofing systems naturally create this required cavity through:

• Battens
• Counter battens
• Purlins
• Tile roof profiles
• Furring strips
• Raised metal roofing systems

This is why RoofingFoil™ products integrate especially well beneath metal and tile roofing assemblies.

Which Product Should You Choose?

Use RoofingFoil™ + Underlayment All-in-One When:

• Performing a full roof tear-off down to the decking
• Installing tile roofing, over your primary waterproofing layer
• Installing a completely new roofing system
• The existing shingles or underlayment are deteriorated, damaged, or old
• A complete synthetic underlayment is required
• You want both waterproofing and radiant barrier performance in one product

Use RoofingFoil™ Single-Sided Solid When:

• The existing underlayment remains in good condition
• Existing shingles are remaining in place
• You only need a radiant barrier layer
• You want a more economical retrofit approach
• The roofing assembly already has a proper waterproofing layer

Why Most Contractors Prefer the All-in-One System

From a building science perspective, the All-in-One product is often the cleaner and more comprehensive approach because it integrates the waterproofing layer and radiant barrier into a single engineered system.

Rather than layering multiple separate materials together and relying on the condition of an older underlayment beneath, the installer starts with a fresh high-performance roofing underlayment that also delivers radiant heat reflection.

That becomes particularly important on tile roofs and full re-roof projects where long-term durability, code compliance, and moisture management all matter. Note on tile roofing: many tile roofing jobs spec at least 2 waterproofing layers. If this is the case in your area, the RoofingFoil™ product will be your top-most layer, with the foil facing up, toward the sky and the air gap. 

The Single-Sided product remains an excellent option for retrofit situations and economical radiant barrier upgrades, but when the roof deck is already exposed or the roofing system is being rebuilt from scratch, the RoofingFoil™ + Underlayment All-in-One product typically provides the most complete roofing assembly insulation solution.