Choosing underlayment for a metal roof installed over existing shingles takes more than picking a roll with strong water resistance. The right material depends on the metal roofing system, the condition of the existing roof, local code, and whether the panels will sit over shingles or over a separate batten system. The products below offer different approaches, but they are not automatically approved for every retrofit. Check the metal panel manufacturer’s instructions and local requirements before you buy or install anything.
Table of Contents
Quick Comparison
| Product | Type | Standout feature | Best suited for |
|---|---|---|---|
| Zeluga 32-390 Synthetic Roofing Underlayment | Mechanically attached synthetic | 95 GSM woven polypropylene; 180-day UV exposure rating | Projects calling for a large synthetic roll, subject to system approval |
| Grip-Rite ShingleLayment HT | Roof-deck underlayment; listing describes self-adhering installation | Slip-resistant surface and temporary exposure protection | Installers who confirm the exact product and application instructions first |
| SIPA 100 GSM Synthetic Waterproof Underlayment | Synthetic underlayment | 1,000-square-foot roll; stated compatibility with metal roofing | Projects that need a synthetic membrane and follow its fastening instructions |
| Titanium PSU30 Peel & Stick | Self-adhering membrane | Peel-and-stick application and slip-resistant surface | Approved areas where an adhered membrane is specified |
| Tyvek Protec 200 Roof Underlayment | Synthetic roof underlayment | Class A fire rating and stated six-month exposure protection | Projects seeking a lightweight synthetic option with stated code approvals |
Our Picks: Best Underlayment For Metal Roof Over Shingles reviews
1. Zeluga 32-390: Large-Roll Synthetic Underlayment
The Zeluga 32-390 is a mechanically attached synthetic underlayment made with 95 GSM woven polypropylene. Its 48-inch-by-250-foot roll covers 1,000 square feet, which can mean fewer roll changes on a larger roof. Printed fastening and overlap guides are intended to help with placement during installation.
The product has a textured, slip-resistant surface and a stated UV exposure rating of up to 180 days. Its listing also cites ICC-ES ESR-5197 and AC188 criteria, ASTM D8257, and regional approvals. Confirm that those approvals and the installation method match your project and local code; a general roof-underlayment approval does not by itself establish suitability over shingles beneath a particular metal panel system.
This is a practical candidate when a project calls for mechanically fastened synthetic material and the roof-system instructions allow it. Its large roll and printed guides are useful details, but the product data does not establish that it should be laid directly over old shingles. Check the required substrate, fastening pattern, and any need for battens or another separation layer.
Pros:
- Large roll covers 1,000 square feet.
- Woven polypropylene construction with a stated 95 GSM weight.
- Textured surface and printed fastening and overlap guides.
- Stated UV exposure rating of up to 180 days.
Cons:
- Mechanical fastening may not suit every retrofit or metal-roof assembly.
- Direct use over shingles is not established by the supplied product details.
Verdict: Choose the Zeluga if your approved roof assembly calls for mechanically attached synthetic underlayment and you value a large roll; do not treat it as a universal layer for covering shingles.
2. Grip-Rite ShingleLayment HT: A Product to Verify Before Buying
Grip-Rite ShingleLayment HT is described as a polypropylene roof-deck underlayment with a woven, slip-resistant surface. The listing also describes a self-adhering, self-sealing peel-and-stick installation, while other details refer to plastic cap nails. Because those descriptions point to different attachment methods, verify the exact product packaging and current installation instructions before ordering or planning the job.
The supplied details state that the material is UV-treated for up to 180 days and designed to resist tearing, cracking, and moisture during temporary outdoor exposure. A non-skid top surface and slip-resistant base are also listed. These features may help with handling during installation, but they do not answer whether the membrane is approved over existing shingles or compatible with your metal panels.
This option could suit a project if the actual product is the intended version and its instructions match the roof assembly. It is less straightforward than the other picks because the supplied description leaves the attachment method unclear. Ask the seller or manufacturer to confirm the exact SKU, required substrate, and approved use before relying on it.
Pros:
- Listing describes a slip-resistant top and base.
- Stated UV exposure protection of up to 180 days.
- Polypropylene construction is described as tear- and moisture-resistant.
Cons:
- Supplied details are unclear about whether it is peel-and-stick or mechanically fastened.
- Suitability for installation over shingles is not established.
Verdict: Consider Grip-Rite only after confirming the exact product and its attachment instructions with the manufacturer or seller.
3. SIPA 100 GSM: Synthetic Underlayment Listed for Metal Roofs
SIPA’s 100 GSM synthetic underlayment comes in a 48-inch-by-250-foot roll, with stated coverage of 1,000 square feet. Its listing says it is suitable for residential and commercial roofs and compatible with asphalt shingle and metal roof systems. That makes it one of the more directly relevant choices here, though you still need to confirm that it fits the specific metal-over-shingle design.
The product is intended to provide water resistance before and during installation of the final roof covering. Its stated UV exposure limit is up to 60 days, shorter than the 180-day claims for Zeluga and Grip-Rite. The listing also cites ASTM D4869 and ASTM D226 performance specifications and TDI/FBC approval. Check the product’s installation sheet for the fastening method and whether a particular approval applies to your location and roof assembly.
At 100 GSM, it is a substantial synthetic option in this group, but weight alone does not determine compatibility or performance in a retrofit. The supplied installation information calls for a hammer or roofing nailer and roofing nails with plastic caps or cap staples. If you need an adhered membrane or a longer period of uncovered exposure, another product type may be a better fit.
Pros:
- Listing states compatibility with metal and asphalt-shingle roof systems.
- 1,000-square-foot roll coverage.
- 100 GSM synthetic construction.
- Stated TDI/FBC approval and ASTM performance specifications.
Cons:
- Stated UV exposure limit is up to 60 days.
- Compatibility with a metal roof does not confirm approval for every over-shingle installation.
Verdict: SIPA is a strong option to investigate when you want a synthetic underlayment explicitly listed for metal roofing, provided its instructions approve your retrofit assembly.
4. Titanium PSU30: Peel-and-Stick Membrane for Approved Applications
Titanium PSU30 is a self-adhering roof underlayment with a stated minimum thickness of 45 mils. The listing describes an asphalt-to-asphalt lap system, all-temperature performance from -40°F to 240°F, and a slip-resistant surface. Unlike the large synthetic rolls, it comes in a 36-inch width and covers two squares per roll.
A peel-and-stick membrane can be useful when the roof design calls for an adhered layer, but the listed lap system and product details do not confirm that it can be applied directly over existing shingles. Before choosing it, confirm acceptable substrates, surface preparation, temperature limits, and compatibility with the metal roofing materials. Follow the product instructions rather than assuming that self-adhesive means it will bond correctly to an old shingle surface.
The smaller coverage per roll may also mean more seams and handling compared with the 1,000-square-foot options. Its stated six-month UV exposure rating and temperature range may be useful for projects with exposure concerns, but only if the installation and roof design call for this membrane.
Pros:
- Self-adhering installation for assemblies that specify a peel-and-stick membrane.
- Stated temperature performance from -40°F to 240°F.
- Slip-resistant surface and stated six-month UV exposure rating.
Cons:
- Two-square roll coverage is smaller than the large synthetic options.
- Supplied details do not confirm direct application over shingles.
Verdict: Choose Titanium PSU30 when an approved roof design specifically calls for a peel-and-stick membrane, not simply because you are installing metal over shingles.
5. Tyvek Protec 200: Lightweight Synthetic with Stated Code Approvals
Tyvek Protec 200 is a synthetic roof underlayment supplied in a 4-foot-by-250-foot roll with stated coverage of 1,000 square feet. The listing gives a roll weight of 36 pounds and a thickness of 16.5 mils. It also describes the product as wrinkle-free, with a Class A fire rating under ASTM E110 and a 50-year limited product replacement warranty.
The product details state up to six months of protection and cite ICC-ES AC188 approval and Miami-Dade County approval. Those details may matter when your project requires a specific approval, but they are not a substitute for checking the current product documentation and local code. The supplied information does not state that Protec 200 is intended to be installed directly over shingles beneath metal panels.
Compared with the thicker or higher-GSM options in this list, Tyvek is a lightweight choice with clearly stated roll coverage and approvals. Its stated warranty and fire classification may be useful selection factors, but make sure the warranty and approval apply to the planned use. Confirm the required attachment method and whether the metal-roof manufacturer allows this membrane in the assembly.
Pros:
- 1,000-square-foot roll with a stated weight of 36 pounds.
- Stated Class A fire rating under ASTM E110.
- Listing cites ICC-ES AC188 and Miami-Dade County approval.
- Stated exposure protection of up to six months.
Cons:
- Direct installation over existing shingles is not established by the supplied details.
- Its stated 16.5-mil thickness is less than the Titanium PSU30 minimum thickness.
Verdict: Tyvek Protec 200 is worth considering when its stated approvals and lightweight roll suit your project, but verify its role in the metal-over-shingle assembly before purchasing.
How to Choose Underlayment for a Metal Roof Over Shingles
Confirm that the existing roof can stay in place
Before comparing rolls, find out whether your metal roofing manufacturer and local code allow installation over the existing shingles. The number of existing roof layers, roof condition, deck condition, added weight, and local rules can affect whether shingles may remain. Underlayment does not fix a damaged roof deck or make an unsuitable roof ready for a new covering.
Understand the exact roof assembly
Metal panels may be installed using different systems, including assemblies with battens or other separation layers. The correct underlayment and its location depend on that design. Ask whether the membrane goes on the roof deck, over the existing shingles, or in another position, and whether the panels need an air space or a specific supporting surface.
Match the material to the manufacturer’s instructions
Synthetic underlayments are commonly mechanically fastened, while peel-and-stick products adhere to an approved substrate. Neither type is automatically right for every metal roof. Check the panel manufacturer’s instructions and underlayment documentation for approved materials, fastening patterns, lap dimensions, and any required separation layer.
Check exposure limits and job timing
Temporary UV exposure ratings matter if the roof will remain uncovered during the work. The products here list exposure limits ranging from up to 60 days to up to 180 days or six months. Treat those as product-specific limits, not as permission to delay the finished roof; follow the applicable instructions and protect the roof as required.
Compare coverage, weight, and installation method
Several products come in rolls covering 1,000 square feet, while Titanium PSU30 covers two squares per roll. Larger rolls can reduce roll changes, but size is only one part of the decision. Consider the roof layout, crew handling, fastener requirements, seams, substrate condition, and whether the product’s application method is practical for the approved assembly.
Verify approvals and warranty terms
Listings may cite standards, regional approvals, or warranties, but requirements vary by location and roof design. Confirm the exact product’s documentation, check that approvals apply to your project, and understand any limits in the warranty. If you are unsure whether an approval covers an over-shingle metal installation, ask the manufacturer or a qualified roofing professional.
Frequently Asked Questions
Can I install metal roofing directly over shingles?
It depends on the metal roofing system, the existing roof’s condition, and local code. Some systems may allow an overlay with specific preparation or support; others may require removal of the shingles. Check the panel manufacturer’s instructions and get a qualified assessment before proceeding.
Do I need underlayment between shingles and metal roofing?
There is no single answer for every roof assembly. The required layers and their placement depend on the metal panels, installation method, local requirements, and manufacturer instructions. Do not assume that any roll labeled “roof underlayment” is approved to go directly over shingles.
Is synthetic underlayment better than peel-and-stick?
Neither is universally better. Synthetic products are typically mechanically attached, while peel-and-stick membranes are designed to adhere to suitable substrates. Choose the type specified for your assembly and confirm that the substrate and installation conditions meet the product instructions.
Which product in this list is explicitly described as compatible with metal roofing?
The SIPA listing specifically says it is compatible with metal roof systems. That statement does not confirm every metal-over-shingle use, so check the product documentation and the metal panel manufacturer’s instructions before installation.
How long can these products stay exposed before the metal roof is installed?
The supplied product details state up to 180 days for Zeluga and Grip-Rite, up to 60 days for SIPA, up to six months for Titanium PSU30, and up to six months for Tyvek Protec 200. Exposure ratings are product-specific; follow the label and installation instructions for the exact product you buy.
Can I use roofing nails with any of these underlayments?
No. Attachment requirements vary by product. The SIPA details specify roofing nails with plastic caps or cap staples, while Titanium PSU30 is described as self-adhering. Confirm the required fasteners and pattern for the exact product and roof system.
Final Recommendation
For a metal roof over shingles, start with the roof assembly—not the product label. SIPA is the most directly relevant choice in this group because its listing specifically mentions metal roof compatibility, while Zeluga offers a large roll and a stated 180-day UV exposure rating for approved mechanically attached applications. Titanium PSU30 is the peel-and-stick option when an adhered membrane is specified. Before buying any of them, confirm that the existing shingles may remain and that the underlayment, substrate, and installation method are approved for your specific metal roofing system.
