Typically, shingles or metal roofing come to mind when most people think of roofs. But some people might not be aware that there’s an additional layer of defense directly on top of the roof deck and underneath the roof covering that plays a crucial part in preventing moisture damage to your property. The term for it is roofing underlayment.

Learn more about this vital part of the structure of your roof.


The material known as roofing underlayment is positioned between the roof shingles and the roof deck, which is commonly made of plywood or OSB. It is built directly on the roof deck and offers an additional layer of defense against the wind, rain, and snow.


The two primary kinds of roofing underlayment are as follows:

  1. Feelings and 
  2. synthetics

Each product has advantages and disadvantages, and the kind you select may be influenced by your location, the roofing materials used, the design of your roof, your budget, and any recommendations your roofing contractor may make.


One of the original kinds of roofing underlayment is felt. It is made by soaking fiberglass mats or paper in asphalt.

There are commonly two varieties of felt roofing underlayment: No. 15 felt and No. 30 felt. No. 30 felt is frequently thicker, tougher, and potentially less prone to tearing or ripping off during installation or weather events than No. 15 felt.


Cost is the biggest benefit of utilizing felt as roofing underlayment. Felt underlayment is frequently chosen by homeowners on a tight budget since it is typically less expensive than synthetic underlayment.


Felt underlayment has a number of drawbacks when used on a roof. Traditional felt roofing underlayment has the drawback of typically not being able to be left exposed for longer than a few hours. The heat could cause the material to dry out or leach oils. This would have an effect on the felt’s capacity to repel moisture.

Among felt underlayment’s further downsides are:

  • prone to tearing in strong gusts and after being installed.
  • It becomes more difficult for the shingles to lay flat if the mat is exposed to moisture, which can absorb water and cause the felt to wrinkle. In order to offer the best protection, shingles should ideally be laid as soon as the felt roofing underlayment is.
  • Due to its heavier weight, felt underlayment might be more difficult for roofing workers to carry in rolls up a ladder and onto a roof.
  • Additionally, because of its slippery surface, the installation might occasionally be more challenging.
  • Additionally, the weight results in less material for each roll. Instead of a single circuit with no laps, which implies there are more potential seams.


If felt underlayment is installed, you might not be able to take advantage of the manufacturer’s warranty because it might call for synthetic underlayment.


Many roofers are opting to use synthetic roofing underlayment in order to increase water resistance and protection from the weather. These items are frequently made of durable polymers, which provide strength and longevity. When laid properly, this kind of underlayment provides superior weather protection to feel since it is often moisture-resistant.

Since the materials used in synthetic roofing underlayment are not specified, different producers may produce their products differently, resulting in products with varying degrees of performance. Do your homework and consult a reputable contractor before choosing the roofing materials that will best protect your home.


Installing synthetic roof underlayment rather than felt has four key benefits. Synthetic roofing underlayment is superior to felt because it:

  • Tough, 
  • quick, and 
  • safe to install, 
  • repels water

Underlayment for synthetic roofs is incredibly robust. When there is some lead time before your roof covering is placed, it is especially advantageous because it generally doesn’t tear and is sometimes acceptable for prolonged UV and moisture exposure.

The durability of synthetic underlayment is particularly crucial when your roofing contractor is moving around on it while it is being installed. We refer to this as “use after abuse” at Wayne Roofing because the product may continue to function as intended even after the damage it receives during installation.

Additionally, synthetic roofing underlayment frequently is:

  • Lighter* – in some circumstances up to four times lighter
  • Fast installation – Because synthetic roofing underlayment comes in broader and longer rolls than felt, there is more material per roll compared to felt, which saves your roofers time and maybe speeds up the installation process. For instance, three rolls of synthetic underlayment might be used to cover a standard 2700 square foot home as opposed to 14 rolls of No. 30 felt.
  • Safe – The surface of many synthetic roofing underlayments, such as those provided by Wayne Roofing, has a range of slip-resistant surfaces for better walkability, which is important for worker safety. Indicators of where fasteners should be placed and overlap guides are frequently included, which helps to increase uniformity and precision during installation.
  • Moisture-repellent – Unlike felt materials, which have a tendency to collect water, synthetic roofing underlayments are made to do the opposite. For homeowners worried about moisture intrusion, especially if they want to leave the underlayment exposed for an extended period of time, this is crucial information.

Synthetic underlayment has the distinct benefit over felt in that it often resists mold growth because it is constructed of plastic.


Although many synthetics are reasonably priced when compared to felt, the expense of synthetic roofing underlayment is by far its biggest disadvantage. However, making the initial investment in higher-quality roofing materials can end up saving you money. The comfort of knowing that your roof is adequately shielded from moisture cannot be priced.


There are numerous things to think about when choosing the sort of underlayment to utilize, whether you’re starting a new house construction project or a reroofing project. In order to safeguard your roof and house from the threats of water and moisture intrusion, synthetic roofing underlayment has numerous advantages over felt.

Find a local independent roofing contractor in Wayne Roofing and discover more about our assortment of roofing underlayment materials.