What Kind Of Underlayment Do You Need For Your Tile Roof?


The roof of your home takes a beating. Day after day it stands up to the elements and protects your house and the people and belongings inside. Exposure to sun, wind, rain, snow, sleet, hail, and ice creates wear and tear on the roof that, if unchecked, can create issues with moisture, mold, mildew, and leaks.

The exterior layer of roofing tiles that we see is the first line of defense against these elements, but the layer that we don’t see, the tile roof underlayment, is equally important to protect the home. Installed between the roof deck and the roof tiles, underlayment is the last line of defense against roof damage and leaks.

What Is Underlayment?

Underlayment for a tile roof is the layer of protection that is installed between the actual roof, typically plywood or OSB, and the exterior layer of roofing tiles. It creates a water-resistant barrier that protects the roof in the event that water leaks under the roof tiles or they are cracked or broken.

Types Of Underlayment

There are two main types of underlayment: Asphalt felt and Synthetic.

Asphalt Felt Underlayment

Asphalt felt underlayment is manufactured by soaking a base material in asphalt to create a water-shedding barrier between the roof and the roof tiles. This underlayment does improve the durability of the roof as a whole, but can tear easily at the fasteners and if exposed as a result of a broken or cracked shingle. If the underlayment tears, moisture can get to the roof directly and cause water damage, mold, mildew, or leaks.

Felt underlayment comes in two different weights — #30 felt and #15 felt with #30 being more heavy duty and better able to stand up to the elements in the event that it’s exposed. It’s heavier than #15, making it more difficult to get onto the roof and work with. Asphalt felt underlayment is less expensive than synthetic, but doesn’t offer as much protection.

Synthetic Underlayment

Synthetic underlayment for tile roofs is manufactured from durable polymers and offers many advantages when compared to asphalt felt underlayment, namely its lighter weight and resistance to moisture and fungal growth. It’s stronger than felt underlayment which makes it better able to withstand impacts from hail or other debris. Because of its increased durability, it is easier to install without causing damage to the underlayment that could allow moisture to reach the roof deck and cause leaks.

This material is more expensive than felt underlayment, but it is also more durable and can last longer on your roof.

Considerations For Choosing Roof Underlayment

Weather Conditions And Climate

In areas with relatively mild or moderate weather, asphalt felt may provide enough protection between the roof tiles and roof deck. In areas where extreme weather occurs, regardless of whether it’s extreme heat, storm, and hail events, or snow and ice, synthetic underlayment provides superior protection against damage if the layer of roof tiles is damaged.


Budget is typically at the top of the list when it comes to considerations during a home project. Asphalt felt is less expensive than synthetic underlayment, but in the event that the roof tiles are damaged, asphalt felt doesn’t provide as much protection as synthetic.

From a budgetary perspective, it might make sense to have a higher upfront cost for a product that will provide superior protection and require fewer costly repairs throughout its life.

Roof Slope

Depending on the slope of the roof, there may be specific recommendations for installing underlayment and the amount of overlap there should be.

Choose Synthetic Underlayment For Superior Protection And Durability

Synthetic underlayment is made from plastics like polyethylene or polypropylene that provide superior strength, elasticity, durability, and waterproofing. It is also resistant to fungal growth in the event that it is exposed to moisture.

When synthetic underlayment is paired with synthetic roof tiles, like Spanish Barrel Tiles, Old World Slate, or Cedar Shake, it creates a highly durable roof that will withstand the test of time, and the elements, to keep your home protected.

Contact the experts at Brava today to discuss the advantages of choosing synthetic underlayment for your roof.