Have you ever approached a roofing project and wondered: is roofing felt necessary?

For much more than 25 years institutions such as the national Roofing home builders Association (NRCA) and also the Canadian Asphalt Shingle Manufacturer’s combination (CASMA) have had roofing felt in your roofing and waterproofing recommendations. The is also a need under many building codes.

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Read on to understand the function of felt paper on roofs, and also how this product will add an integral class of protection to your roof – and your residence.

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What is roofing felt paper?

Sometimes referred to as roofing feeling underlayment, roofing tar paper, or roll roofing, this is a class of defense installed between the roof deck and also the roofing shingles.


Roofing felt is consisted of of a base, do from herbal materials (such as lumber cellulose) or artificial ones (such as fiberglass or polyester), and also then coated or saturated with a protective coating such together bitumen (asphalt), i m sorry repels water but still enables the product to breathe.


Why usage roofing felt paper?

Roofing experts have uncovered that including a class of protection between your structural roof decking (the layer of lumber that covers her rafters) and your roof shingles helps create a better-looking and also longer-lasting roof. In fact, there are a variety of important methods roofing feeling not just protects her roof, but additionally your residence. For example:

It repels waterWind-driven rain or snow can trap water under your shingles, putting your roof deck and inner residence at danger of moisture damage, leaks, rot and also mold. Roofing felt help ensure the water drains turn off the roof – and doesn’t leak right into your home.
It provides backup protection in the event of ice cream or water damageIn northern climates, ice or eye dams are another common cause of residential water damage. Once the warm from your home melts snow or ice on her roof, the water can then seep into your roof’s nooks and crannies and ultimately into your residence, causing damage to ceilings, walls, or insulation. Your best protection versus an ice cream dam is one ice and water protection membrane which deserve to seal around the shanks of the roof fasteners because that a leak-resistant fit. However, roofing feel offers extr protection versus leakage, offering an extra layer of water resistance.It offers extra weather protectionAlthough your shingles are your roof’s first line that defense versus the elements, having actually a backup layer that weather security underneath helps expand the life of her roof deck. And, in the occasion of a major weather occasion that division your shingles loose, the roofing feeling guards your wood deck versus rain and water until the shingles have the right to be replaced.It protects her roof deck while you job-related on itRoofing felt stays clear of the deck from gift exposed come the aspects before, or while, the shingles room being applied.
It avoids wood resin stainsWhen you usage certain varieties of hardwood to construct your deck, over there is periodically a risk the lumber will leach tiny amounts the resin over time as the ages. Having a layer of roof felt will block the resin, staying clear of it from staining or compromising her roof shingles.

When to use roof underlayment

No matter what form of asphalt shingle you space using, whether traditional or much more robust formats (such as under premium designer, architectural and also performance shingles) the is encourage to use a underlayment.


Which weight is ideal for your project?

For countless years, roofers provided asphalt saturation felt under roofing shingles, and it to be historically obtainable in two conventional weights: 15 pounds every hundred square feet and 30 pounds every hundred square feet. The 15 pound was for lighter weight projects, when the 30 offered more heavy duty protection. Today, the yes, really weights have actually changed, however the categories have stuck.

No. 15 No. 30
Use a single layer that this diluent product because that lighter duty projects, and also steeper pitched roofs (which permit water to run off easier).Use one or two layers the this more thick product for remarkable protection.
In part cases, a synthetic underlayment have the right to be used as a an ideal alternative.Use especially under slate or tile shingles.
This is the minimum weight numerous professional associations recommend, and many structure codes require.

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Consider for slopes between 2:12 and 4:12 which are much more prone to wind-driven rain.