Why Synthetic Underlayment Matters on a New Roof
Homeowners usually focus on the part of the roof they can see: the shingles, tile, or color. But one of the biggest product shifts in roofing is happening underneath the finished roof surface. More reroof projects are moving away from old-school felt and toward synthetic underlayment, and for good reason.
The underlayment is the layer between the roof deck and the finished roofing material. It is not the flashy part of the job, but it plays a major role in short-term weather protection during installation and as a secondary barrier if moisture gets past the outer roof covering. NRCA notes that underlayment serves several functions, including limited weather protection before the roof covering is installed and secondary weatherproofing if water infiltrates the roof covering.
That matters because traditional asphalt felt has some limitations. NRCA explains that some felt underlayments can wrinkle and buckle if they get wet before the roof covering goes on, and they generally should be covered as soon as possible after installation. The same NRCA source says synthetic underlayments are typically lightweight, high in tensile strength, have low or no moisture absorption, and experience less shrinkage and wrinkling.
In other words, synthetic underlayment is gaining attention because it can offer a cleaner, tougher platform under the finished roof. Owens Corning describes its ProArmor® synthetic underlayment as strong, durable, and water-repellent compared with 15-pound felt. CertainTeed describes DiamondDeck® as a premium synthetic underlayment engineered for residential roofing applications and says it is designed to resist tears, punctures, and impacts. owens corning
This is especially relevant in Southern California, where roofs are exposed to long periods of heat and UV, followed by bursts of wind-driven rain. A reroof here is not just about installing fresh shingles. It is about building a roof assembly that handles dry heat, seasonal weather swings, and the real-world conditions that show up during construction. If the outer roof covering is the armor, the underlayment is part of the backup defense plan.
There is also a code-and-standards angle worth watching. NRCA notes that synthetic underlayments complying with ASTM D8257 gained approval through code-change proposals with the International Code Council, even though older model codes did not specifically reference them by name. That tells you something important: synthetic underlayment is no longer a fringe upgrade. It is increasingly part of the mainstream conversation around better roof assemblies.
Of course, not all synthetics are the same, and underlayment is only one part of the system. The quality of installation still matters. Fastener pattern, overlap details, deck condition, flashing, ventilation, and compatibility with the final roofing material all affect performance. A better product does not cancel out rushed workmanship. But when a homeowner is already investing in a new roof, upgrading the layer beneath the shingles can be one of the most practical decisions in the entire project.
The biggest mistake homeowners make is treating underlayment like a commodity line item. It is not. On a well-designed reroof, the layers you do not see often determine how well the visible roof performs when the weather turns.
If you are planning a reroof, ask Rocket Roofing not just what shingle or tile is going on top, but what underlayment system is being installed underneath—and why that choice fits your home.
Owens Corning Roofing Products
Owens Corning Roofing Products
Rocket Roofing is proud to be selected as an Owen’s Corning Approved Roofing Contractor.
Owens Corning is a leader in roofing shingles, underlayment and components products. The look of a roof can have a significant impact on the overall design and perceived value of a home. After all, the roof can make up half of a home’s exterior.
Owens Corning systems look better, last longer and offer more choices to perfectly fit your project.
Rocket Roofing is proud to be selected as an Owen’s Corning Approved Roofing Contractor.
Owens Corning is a leader in roofing shingles, underlayment and components products. The look of a roof can have a significant impact on the overall design and perceived value of a home. After all, the roof can make up half of a home’s exterior.
Owens Corning systems look better, last longer and offer more choices to perfectly fit your project.
