How do I Choose the Right Underlayment For My Roof?
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The 411 on Underlayment

Published by Andrew Schmidt

What is roofing underlayment?

Roofing underlayment is a special barrier installed between the roof substrate and the roofing material in its surface (shingles, tile, membrane, etc.). It provides extra protection to the roof structure and the interior of the home against water leaks.

How do I choose the right underlayment for my roof?

The goal is to get an underlayment that will give you the most protection at a price you can afford. It is first important to know the different kinds available:

Felt is tar or asphalt saturated paper made with some fiberglass. It is the most widely used and cheapest type of roofing underlayment available. It offers a general level of protection against leaks, but if you live in an area with heavy rain or snow fall, it may not be enough. Felt is not as high quality as synthetic underlayment, and doesn’t last as long, as it is susceptible to tearing.

Ice shield, or I&W, is a thick asphalt or bitumen based reinforced membrane with a sticky surface that glues to the roof deck. In northern states and Canada, building codes may require the use of ice shields because of its strong protection from water penetration, and the fact that it won’t tear after installation. It is best to install the ice shield when the air temperature is at or above 40°F. The ice shield should be installed at the bottom three feet of the roof, and the rest of the roof can be covered by regular underlayment. When an ice shield is installed over the entire roof deck, it can trap water under the roof, which can cause the substrate to rot or form mold and mildew.

Synthetic underlayment is an expensive substitute for felt and has a number of advantages: it lasts longer, is tear-proof and generally does not deteriorate. This type of underlayment can be breathable or non-breathable. Non-breathable, similar to the ice shield, may trap moisture under the roof.

Depending on where you live and what your budget is, you can determine which kind of underlayment you want for your roof. Synthetic can extend the life of your roof by five to 10 years, but at an additional expense. If you live in an area that gets a lot of snow, ice and rain, it is wise to invest in an ice shield combined with either felt or synthetic underlayments.

For premium roofing materials, synthetic underlayment will provide an adequately long-lasting second layer of protection. If you live in a mild climate with minimal rainfall, your roof may be properly protected with felt underlayment.

If you have any additional questions about underlayment options and which will fit your needs and budget, give Showalter a call today!



Courtesy of Roofing Calculator

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