What Roofing Underlayment Should I Use? Best Materials Pros&Cons

A perfectly installed roof is the only barrier between natural disasters and your home. It’s what protects you and your stuff.

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We know all the basic principles such as the roofing material to choose, the colour and how it will complement the house.

You hire a professional roofer and within a few days your house will have a brand new roof. In fact, most people install a new roof when they replace their house. This investment increases the value of your home many times over.

What if you live in an area where it rains a lot? Their roof was damaged by the recent storm that hit the city.

They just put the house on the market. Here is your chance to increase the selling price of your home by installing a new roof, but there are a few things you should consider first.


You know your roof protects you.

But have you ever wondered how?

Two words: Payment for the roof.

Not the roof, but this protective layer prevents, among other things, water from entering your house. Without that, your roof is vulnerable to harsh weather conditions.

What is a roof load?

It is a waterproof or water-repellent barrier material installed on the roof deck. The material goes directly under the roof and acts as a protective shield against the weather.

If your roof cracks, you can rest assured, because this small contribution will help you prevent further damage.

There are three types of tampons:

  1. Rubber asphalt surface (waterproof *)
  2. Asphalt saturated felt base (waterproof *)
  3. Synthetic substrate without bitumen (waterproof *)

The first subfloor is waterproof and the other two are waterproof.

*Indication* Most people are confused about the difference between water resistance and water resistance. The first term (water resistant) means that the pillow is resistant to water, but only for a certain period of time. On the other hand, the latter term (waterproof) means that the pillow is completely protected against water.

Rubber payment by asphalt

Rubber-like asphalt contains rubbery polymers and asphalt. Of the three substrates it is the most expensive because it is waterproof.

This underpayment is like sticky paper. Before applying this substrate, the support membrane is removed. The adhesive material serves as a watertight seal. It also protects the edges of the roof against leaks. This material is very useful in areas such as eaves and valleys on the roof.


  • The only waterproof material for this kind of work.
  • Low installation costs : It can be expensive, but it is easy to apply.
  • Long lifespan: Rubber asphalt is supplied in rolls, which means that there are few joints. This reduces the chance of water getting into the attic. This underpayment can last for 50 years.
  • UV resistant: It is resistant to the UV rays of the sun.
  • Durable: Compared to pure asphalt, rubber does not expand or shrink due to climate change.
  • Easy to fix: A special tape is used to repair cracks in the rubber. That’s usually enough.


  • Rubber underpayment occurs in many forms. Some are fireproof and some are not.
  • You will need a professional to determine this underpayment, which may involve additional costs.

Felt underlay Asphalt Concrete

This substrate, called tar paper, is made of various mixtures of polyester, bitumen, cellulose or asphalt. It is one of the most commonly used materials in older houses and is usually available in two different thicknesses: 15lb and 30lb. The thickness of 30 pounds is clearly more resistant to damage and lasts longer (see video below) :

Asphalt-saturated felt is not recommended in areas with frequent rainfall. The price of felt varies and mainly depends on the amount of asphalt it contains. The higher the asphalt content of the paving, the more durable and expensive it is.


  • Respect for the budget
  • Contains fiberglass, which increases strength and durability.
  • This is good for low roofs, because the water can easily slip off.


  • It weighs more than rubberized asphalt, not asphalt plastic.
  • The installation is quite expensive
  • Decomposes relatively easily by exposure to the outdoor environment.
  • Sensitive to sun damage

Synthetic base without bitumen Payment

In addition to asphalt, this synthetic substrate also contains glass fibre, polyethylene and polypropylene. These three materials give it great stability and make it tear resistant. Some manufacturers provide them with a non-slip material that protects them from water.


  • Durable and durable
  • Light
  • Prevents water leaks and ice dams
  • mold resistant
  • not to be exposed to direct ultraviolet rays…
  • Easy and safe installation


  • Depending on the materials used for its manufacture, it can be very expensive, which is the biggest and only disadvantage.

Finally, if you are installing a new roof, we recommend that you choose the basic rate for rubber asphalt. Yes, it is slightly more expensive than the expensive side, but it lasts longer than other types of materials and will certainly protect your home from water leaks, mould and mildew.

Now let’s look at some of the questions that many people often ask about the cost of roofing.

Is an underlay needed for the roof?


Roofing is more than a necessity, it is the key to making your roof last for years. The underlay of the roof is a waterproof and/or impermeable barrier material that covers the entire roof surface before you install it.

Once installed, it provides much-needed protection against the toughest weather conditions. There are three types of products that fall into the asphalt underlay category: asphalt saturated felt, synthetic non-bitumen underlay and asphalt rubber underlay. Only the rubber-coated version is waterproof. The other two are waterproof.

Although asphalt shingles and other types of roofing are designed to protect your home or building, their low cost makes it possible to achieve a multitude of objectives.

If, for example, shingles overlap, corners are not always properly sealed against the elements and if roofing materials cannot withstand weather fluctuations in strong winds, they cannot be repaired.

Some roofing materials can become brittle with age and a disaster in the form of an unventilated attic can put even more pressure on the roof if the protection of the rooms underneath is not badly rewarded.

Contractors state that the most sensitive areas under the roof to be protected are eaves, valleys, overhangs and low roof surfaces. This is where the underpayment comes in to help keep the houses dry and protect your investment.

Are synthetic roofing materials better than asphalt-saturated roofing felts?

This debate is a passion for preferred roofers. So it can be said that both types of roofing have their own fan clubs.

Plastics are preferred for several reasons: They can be laid quickly, remain stable in strong winds and offer better traction than asphalt products in bad weather. But the plastic is worth it: They are more expensive, especially if you choose a synthetic product that is considered to be vapour permeable.

Asphalt felt, on the other hand, has proven its worth, is easy to install and you have no faults if you choose this material. Saturated asphalt was the only option on the market until the synthetic, also known as non-bituminous synthetic substrate, became available about 15 years ago.

This means that you may not have a choice if local building regulations require the installation of asphalt felts.

Some building regulations require this material to have fire-retardant properties. Sold in different grades (#15 or #30), felt base layers are generally made from recycled corrugated paper and sawdust and impregnated with asphalt. Although it acts as a vapour barrier, it is best avoided when attics and decks are poorly ventilated.

Your last option, rubber asphalt, is the only truly waterproof product on the market and is very expensive, but in regions known for their harsh winters, rubber asphalt is often the most sought after and preferred by roofing companies who want to guarantee the best protection for their building against extreme cold conditions.

What is the best price for a metal roof?

green metal roof on a wooden house

Metal roofs have excellent waterproofing properties, this type of roof is affordable, and if you choose a metal roof, the roof of the building will not last long.

Which type of underpayment offers you the best protection and value? Almost everything on the market, professionals say.

Basic rule: If it is designed to be installed under a tiled roof, it can also be used under a metal roof.

However, if you have to choose a type of underlay for a metal roof, a synthetic underlay is a better choice than asphalt products.

A metal roof usually consists of three layers. The first serves as a shield against ice and water, probably made of rubber containing asphalt or butyl adhesive with a polyethylene backing film.

The second layer is usually a reinforced polypropylene blanket, consisting of several layers to add a moisture barrier.

The third layer, which is essential for houses with metal roofs in warm climate areas, has reflective or breathable insulation properties that allow heat to be stored and dissipated.

A warning when choosing an underlay for your roof: Make sure you choose an underlay that does not scratch the metal roof panels.

What is the best rate for tiled roofs?

Tiled roof

Because cladding and lighting are the most critical protection against the water barrier, they are demonstrably even more important than the roof itself.

Tiles provide the finishing touch by adding an edge to the house or building so that the exterior blends in perfectly. With an adequate down payment and assuming that both tiles are professionally installed, you can expect them to last for 50 years.

When it comes to the material and construction of tile underlays you hear a lot about paper and felt, but most of the time they are used interchangeably and are referred to as organic felt.

But felt isn’t the only material you come across: Fibreglass fabric can be replaced by this more traditional material. At the same time, materials with a lower value are regularly classified by weight.

For example, a 90-pound paper describes. B. a cheap, low-grade, gravel-covered material that can only be used if nothing else is available.

The best choice would be a product consisting of 2 layers of 30 pounds of felt impregnated with asphalt. This equipment will probably last 20 to 30 years. Upgrade to a double layer of SBS modified high quality asphalt and you are ready for the long term.

The fibreglass option mentioned above is still available if you are convinced that it is the best way to support a roof tile, and if you have followed the roofing trends, you know that self-adhesive membranes that adhere directly to the roof are now preferred by roofers who want to save time, money and energy.

This material is made with synthetic rubber additives, and if you choose the 40-pound version, you will extend the life of your roof impressively.

What is the best roofing material for asphalt shingles?

Tiled roof

Once upon a time there was only one kind of underpaid tile, and you’ll recognize that name when you read it again: Felt paper.

As the industry has embraced new materials that have proven to be more efficient, sustainable and versatile, numerous water-repellent layers have been brought onto the market to support the shingles. The most popular and best-selling tiled roof alternatives at the moment? Synthetic.

Like the synthetic substrates described in the above categories, they have a higher price, but offer unique advantages that are unrivalled. They are lighter, have excellent water resistance and when it comes to flattening the shingles so that they do not bend or warp, there is no alternative.

How effective are synthetic substrates? This means that, if necessary, they can be used as roofing without tiles at short notice!

What makes these products so durable and adds years to the life of the roof? The fact is that they usually consist of two different membranes.

The first is installed around the perimeter of the roof where the roof surfaces form valleys to close off these areas. The second layer is made of a hard-wearing and waterproof material that not only seals the deck, but also provides high tensile strength so that tilers can do their work more efficiently and safely.

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