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What Is Roofing Felt

History Of Roofing Felt

Types Of Roofing Felt

Installing Roofing Felt

Types of Roofing Felt

Materials used in Tar Paper and Felt

Roofing felt is often made from fiberglass fleece that has been soaked with other materials to create waterproof product. Tar-like substances, most often referred to asphalt or bitumen, are impregnating agents that will give the fleece waterproof qualities. Fiberglass-based felts are some of the longest lasting options available. They are not prone to tearing and hold up well against extreme weather.

More recently, polyester fibers have been developed as the base fleece material for roofing felt.  Polyester is also highly resistant to tearing and able to withstand the tough elements.  Polyester roofing felt is also impregnated to asphalt (bitumen) to make it waterproof.

RoofersAnother option is completely organic roofing felt made using the fibers of rags. The material is usually soaked with asphalt for waterproofing, and to retain the organic qualities some people prefer. Like many other organic options, the life span of polyester based roofing felt is not as long as fiberglass. However, advancements in coating have helped extend the life expectancy of these felts.

Technology continues to create improvements for roofing felt. Currently, roofers can choose to use a thermoplastic polyolefin membrane, or TPO, as the underlayment. It is used like roofing felt, but is lighter, more resistance to punctures, and even stronger than polyester roofing felt. It has only been available on the market since about 2003, so it has yet to pass the test of time like traditional felt paper. However, early results are promising. This paper could easily become the roofing felt of tomorrow.

Everything goes high-tech eventually, and roofing felt is no exception. New shingle underlayments are available that provide the necessary waterproofing features along with a slip-resistant coating that makes it safer to walk on. These choices are greatly appreciated by roofers working on steep pitches for their increased traction. They are just as easy to work with, but have proven safer to use.

Other improvements to roofing felt include options that are superior at nail sealing, weigh less and come in wider sheets than the traditional 36”. The materials for these superior roofing felts are more expensive, but that cost is easily offset by the reduced labor rates for installation. If you are working on a particularly large roof, wider rolls can help reduce the number of seams, as well as lowering the overall labor expense of installation.

Some rolls have lines marked on them, making the overlapping process simpler and helping you keep the lines straight. These rolls are easier to use and will help you do a professional job. Keeping the rows straight and even is vital to laying an effective roof underlayment.

You can also choose to use just the roofing felt for roofing. This would primarily be done on sheds and outbuildings, where the expense might not be warranted. If you decide to save money this way, be sure to choose a mineral-surfaced roofing felt as these can last for about ten years.

Roofing Felt Weights

Like many paper-type products, roofing felt paper can be described by its weight, or the density or heaviness of the paper. For the average home, roofing felt that is 15 or 30 pounds will be effective. There are lighter weight felts available, but they will not provide the same protection. The weight that should be used also depends on the particular roofing material that has been selected. Some materials will require heavier weights. Traditional asphalt shingles typically require 15 pound roofing felt.

One thing to keep in mind is that heavier paper is not always better. With a proper roofing job, the felt will be completely protected by the shingles. A lighter weight felt paper will still prevent sap from leaking out and ruining shingles, but it will also allow more air to pass through the paper. Better air circulation can increase the lifespan of some roofing materials.

Sizes Of Roofing Felt

While all tar paper comes in rolls, you do have some control of what size roll you will purchase. The most common width is 36”, although they are sometimes available in other sizes. The rolls are typically either 50 or 100 feet long. Choosing longer rolls will allow you to cover more roof surface with fewer seams. Remember that every seam presents an opportunity for water to get through the barriers and into the home. Therefore, eliminating as many seams as possible will create a stronger barrier. Taking the time to measure the roof will help you determine how many rolls you require for the job, so you don’t wind up purchasing more than you need.


Roofing felt is sold in rolls, so each roll will essentially be one long rectangle. The felt paper is rolled onto the roof, and then cut as needed to match the shape of the roofline. Because it is flexible and easily altered with a utility knife, it can be cut to fit any shape roof. Whether you are dealing with a hip roof, a traditional roof or a Victorian roof with pergolas, roofing paper can easily be adjusted and cut to the perfect fit.

Roofing Felt Manufacturers

These are the top manufacturers of roofing felt and underlayment products in North America.

Choosing the Type of Felt

The first thing you should consult is the directions on your final roofing material.

If the shingles give you a choice between weights, and you live in a milder climate, it is usually advisable to choose the lower weight. Lower weight felt will literally add less weight to your roof, it is more breathable for air to move through, and it costs slightly less. However, if the shingles that you love and really want to use recommend 30 lb paper, that is what you should purchase.
If you live in severe climates that experience cold weather and driving storms, the 30 pounds paper will provide you with a higher level of protection.

Keep in mind that failing to follow manufacturer’s recommendations can result in the warranty being completely voided.