Top Rated Roof Underlayment for Rain & Snow Protection

A reliable, strong and all weather resistant roof is the cornerstone for any home improvement plan. A roof underlayment is the foundation for an all weather roofing. That’s why, more than often, most of the homeowners do seek an answer to the best practices in roofing underlayment ? We will examine this predicament in detail and find the solution towards having the best roof underlayment for your home.

A roof underlayment is the bufferzone, a layer of resistance and protection a roof has against any and all adverse weather condition like rain, hail, snow, and other harmful & damaging forms of precipitation.

We have curated a list of the top and the best roofing underlayments based on our research and market survey

List of the Top Rated Roof underlayments

PhotoProduct CodeSizeExposureDetails
Roof underlayment Titanium PSU30Interwrap PSU3036"x72'180 days
Grace TV71835536"x75'90 days
Roofing Underlayment from Alpha Protech Alpha Protech 48"x250'180 days
Roof Underlayment by TyvekTyvek 403604'x250'90 days
Grace 5003200Grace 500320036"x195'30 days
RubberGard FSRG10X15-60Firestone RubberGard 6010'x15'90 days
Lottes Roofing 10-48-9591Lottes Roofing 10-48-9591 10'x15'28 days
Roofing Underlayment Owens Corning 736642Owens Corning 73664242"x286'30 days
Roof underlayment model GAF 0970GAF 097048"x250'90 days
LL-120 Series SuperLockLL-120 Series SuperLock4'x250'180 days

How To Choose a Roof Underlayment

Irrespective of whether you are doing a new roof construction or re-doing the existing roof, it is imperative for you to be equipped with all the necessary information to ensure that your roof lives up to your expected levels.

One of the factor that affects the performance of your roof in combating the climatic conditions is the roofing underlayment. Let us look at the factors which should be considered while you choose a roof underlayment.

Climate

As a thumb rule, places with hot & humid climatic conditions and with higher UV levels, call for installing Synthetic roof underlayments. By virtue of its in-built qualities, synthetic roof underlayment repel & resist heat, moisture, and bacterial & fungus formation. They also offer a seamless & smooth application.

While places with colder climatic conditions which are prone to frequent rains, winds, rainstorms, gale or snow, should place a strongly built quality Felt underlayments. They have a natural ability to act as a shield to ice and water.

Compatibility

The compatibility of a roof underlayment depends largely on the kind of roofing material which is being used for the roof installation. While each roof material needs some set of specifics from its reinforcement layer, each roof underlayment is also manufactured with certain features which will suit specific roof materials more than the other. It’s like each roof material has a corresponding roof underlayment suited for it.

Traditional shingles perform best with the heavy duty felt underlayments. The fifteen pound felt underlayments provide a good protection along with promoting high degree of air ventilation.

Whereas, metal roofs perform extremely well with synthetic underlayments. They offer a very high degree of resistance to heating which is the major issue with metal roofing. With the sun blazing hot, metal roofs have a tendency to absorb and transfer the heat into the house. With the synthetic underlayments, this issue of transfer of heat gets resolved.

Quality

You don’t have much control over the manufacturing quality of the underlayments being produced. But what you can do is to look out for the product warranty which each of the brands give. A 10 year, 20 year or a 30 year warranty is an indication of the quality of the underlayment being offered by the manufacturers.

Review of the best Roof Underlayments

Interwrap Titanium PSU30 Roof Underlayment

Roof underlayment Titanium PSU30

This is one the most reliable and best crafted roof underlayments available in the market. This super strong roof underlayment offers consistent and water-tight protection from the harsh weather conditions.

Those who want a durable and a fit-to-size roof protection will always have the confusion on whether they have picked up the right product and the brand for their roofing underlayment requirement or not. For a really long lasting product which can bear the effects of harsh climate consistently, you must always pick up a super durable and highly tested roof underlayment only.

Interwrap manufactures an array of Titanium roof underlayments which specializes in super-heavy protection of the roof.

The Titanium PSU 30 underlayment is made with rubberized modified asphalt with a tough surface area consisting of synthetic polymer to make it more resistant to water forces. The self adhesive feature makes it easy-to-install and the self sealing feature prevents sloping and slippages. It has patented an anti slip technology – SURE FOOT for its range of roof underlayments

The Ttianium30 is used on roofs with straight runs and those having slope of 2:12. It is crafted as a ribbed surface with extra performance adhesive feature which gives it a better grip on the deck of the roof. This ensures there are no slips irrespective of the degree of water it gets pounded with during rainy seasons.

The cold grey surface doesn’t allow contraction and expansion under the influence of excessive heat or cold. The synthetic properties do not allow any kind of mold formation on its surface. This roof underlayment is built for consistent performance in extreme temperatures going as low as -40°F  and as high as 240°F. With a direct exposure UV rating of 6 months, it is one of the best roof unlderlayments in the market.

It can be installed directly on OSB, plywood, masonry, and concrete surfaces. It can be left exposed for 180 days before you cover it up. And it is crafted to be used with a variety of roofing like tile, shakes, metal, slate, synthetic and asphalt shingles.

Features:

  • Dimensions: 36  x 75 inches
  • Thickness: 45 mils
  • UV rating: Six months
  • Synthetic construction
  • Length: 72 per roll

Main advantages

  • Suits sloped applications and roofs with straight run
  • High durability
  • Easy to install
  • Adhesive lining
  • Good Fit for variety of roof surfaces
  • High temperature & UV resistance

Grace TV718355 Roof Underlayment

Roofing Underlayment sample by Grace TV718355

If your home is subject to harsh weather conditions like heavy rains, ice or snow, then, having a durable roofing underlayment is of utmost importance, if not critical. It is important for the safety and comfort of your home to have a good underlayment for your roof.

The Grace TV718355 roof underlayment has a high quality membrane with self adhesive feature. This design makes it highly durable and super water resistant.

Made of rubberized asphalt with self adhesive feature and double reinforced with super density polyethylene film, this roof underlayment keeps your roof dry and away from moisture at all times of the year.

To ensure the consistency of its water resistant qualities, it is manufactured with high density raw materials consisting of an extra thick layer of fold-less release paper for enhanced performance as a roofing underlayment.

The self adhesive asphalt rubberized underlayment bonds itself securely with the roofing elements once the paper has been removed during the application process. For enhanced application, the Grace roof underlayment comes in rolls of of 75 feet with multiple width size options – 6″, 9″, 12″ and 18″.

Apart from the superior water repellent qualities, it also guards against various leaks which open up during the rains accompanied with high wind velocity or during instances of ice damming. If applied appropriately to every detail of the roof, this underlayment has the ability to reduce the vulnerabilities of your roof and to make your home a safer and secure place to be.

This waterproof roofing underlayment has high compatibility with a range of roofing designs making it an ideal candidate for reinforcement with almost all types of roofing material – slope induced roofs, standing metal seam roofs, and mechanical attachment roof covers consisting of asphalt, tile, shingles, slate or cedar.

Features

  • Dimensions: 36 x 75 inches
  • Area coverage: 225 square feet
  • Rolls width: 3 feet
  • Membrane strip length: 75 feet

Main advantages

  • Highly durable
  • Improved protection from leaks
  • Flexible width and length
  • Compatibility with a wide range of roof covers
  • Easy to use and very safe to fit

Alpha Protech Roofing Felt Underlayment

Synthetic roof underlayment of Alpha Protech shhet on the top of a roof

The Protech Rex underlayment from Alpha is made with synthetic felt which can withstand UV exposure for 6 months without any issue. Alpha Protech makes for an affordable and reliable roof underlayment, if quality and high resistance is the criteria for you.

This 48250 EPB  UL REX roof underlayment has both the strength in the material and longevity of resistance. Synthetic felt woven into product gives strength to protect the roofs from leakages, severe weather conditions, and moisture.

The set comes with plastic nails with diameter of one inch and 3/8th inch heads. You can firmly fasten the underlayments of your roof with these nails. And if you want it to be even more secure and firm, use the galanized elctro plated shank roofing nails.

The construct of the underlayment is tear proof and slippage resistant with respect to the roof surface. This means that the it will cover your entire roof without slipping off the surface of the roof. This feature also reduces any chance of structural damage during wet conditions.

Not only is this roofing underlayment lighter by ten times when compared to any other average regular roofing felts, it is also stronger than all of them. A single roll sheet of Rex gives round 250 sq. ft. of roof coverage. Compare this with any other underlayment with a coverage of 250 sq ft and you will clearly notice the difference in weight.

A combination of insulation and top surface coolant makes this product resistant to UV exposure for a period of 6 months making this felt a good choice for those living in warm climates.

Features

  • Dimensions: 48 x 6 x 6 inches
  • Synthetic felt
  • Plastic nails
  • Fire rating: Class A

Main advantages

  • High UV exposure resistance
  • High quality but lightweight
  • No slipping issues
  • Synthetic woven material
  • Tear proof

Tyvek 40360 Roofing Underlayment

 

Roofing Underlayment from Dupont Model Tyvek Protek 120

Tyvek has always given immense importance to its manufacturing process, quality of raw materials and functional design of rool underlayments. It is for this reason that it is known for it premium quality and superior product performance and fit.

Its roof underlayments carry a unique reliable emboss pattern on its surface which provides a superior and increased grip of the deck of the roof. Not only you can use this on new roof surfaces, you can use this pattern on the re-roofing requirements as well. The grip of Tyvek Protech 40360 would be same on new as well as old roof surfaces.

It is designed for slopes for 2:12 and higher. Apart from new construction or repairs, this underlayment can be used for house wrap too. It is compatible with all kinds of surfaces including cedas, asphalt, and metal roofs.

It constitutes of six layers of protection, is walk safe, and resistant to water and slippages. The polypropylene woven base gives the underlayment its durability. It is reinforced with a water resistant barrier and the embossed grooved surface removes dirt and water to keep the installation safe. This roofing underlayment is wrinkle free, UV resistant with a 3 months rating, and easy to chaulk.

The Protec 120 comes in a roll of 25 sq ft of material for ready installation. It is easy to apply irrespective of whether being done by you as a skilled homeowner or by professionals hired by you or the contractors. Tyvek has a record of years of service under their belt and a very robust professional testing system for its roof underlayments.

Features

  • Dimensions: 48.1 x 6.3  x 6.3 inches
  • Single roll package
  • Can be applied on various types of roof
  • Easy for repairs and quickfixes to
  • Weight: 11.16 pounds

Main advantages

  • Safe to walk on during installation
  • Good for multiple roof surfaces
  • Uniquely embossed & grooved
  • Suitable for repairs & re-roofing
  • UV resistant rating: 3 months

Grace Select 5003200 Roof Underlayment

Graced Select Roofing material

Insulation of the roof is the primary concern of every homeowner if you are living in an area with hot and humid temperatures. Warmer climates with lots of sun exposure always puts strains on the roofing insulation and other materials used in the roof. It then becomes imperative for you to guard your roof consistently against the harmful UV rays.

The Grace Select roof underlayment comes has a light thin design which makes it easy to install. It is designed to give your roof protection from sun’s UV rays and extreme heat conditions as well.

The underlayment has a self adhesive feature which makes it easy to apply even by skilled homeowners. Made up of fold-less quick release paper, the adhesive line is wrinkle free, resistant to slippages, and good to use even after having being stored for a long period of time.

It suits almost all kinds of roof surfaces and sits well with different slope roof designs of various angles & heights. The rubberized layer of asphalt gives a superior sealing quality to the underlayment. This means a higher degree of protection by reducing vulnerabilities around the surface areas having roof nails.

As it is manufactured to withstand the onslaught of UV rays, the Grace Select is able to give protection from continuous exposure of UV for 30 days. The extra insulation gives this roof underlayment a durability with which it can stand against severe climatic conditions like rain, wind and ice damming without any issues.

It is a versatile product suited for all kinds of roofing material and designs. It is also slippage free, water resistant, and has an universal installation application.

Features

  • Roll dimensions: 3 x 65 feet
  • Type: Single roll package
  • Thickness: 25 mils
  • UV exposure of 30 days
  • Weight: 50 pounds

Main advantages

  • Very durable design
  • All weather protection
  • Features fold-less quick release paper
  • Will not crack to dry out

Firestone RubberGard FSRG 60 Roof Underlayment

Roof Underlayment product Firestone RubberGard FSR 60

Firestone is among the leading manufacturers of materials for new roofing requirements and roof repairs as well. They make some of the best roof underlayments in the industry. Their products are known for their durability and long term product life.

The Firestone RubberGard is made with high quality synthetic rubber performer compounds which are super resistant to UV rays, extreme weather conditions and ozone exposure. They can also take the brunt of sudden drop in temperatures or a consistent low temperature. These qualities increase the life of this roof underlayment.

Apart from the great protection qualities, the RubberGard is designed for DIY installation. It’s easy to apply for various roof repair jobs. Unlike most of the traditional products, this underlayment is very versatile and can easily be outlined in order to fit into a shape per the requirement. It is flexible and can be fixed on low roof slopes as well. It will also hold good for unusual roof area construction.

This roofing underlayment is environment friendly and can be applied all through the year under all kinds of weather conditions. The membranes in the lining can be recycled. Overall the underlayment has high heat resistance.

Being versatile, it can be used for a fully adhered, mechanical or ballasted application.

Features

  • Dimensions: 10 x 15 inches
  • Synthetic rubberized membrane
  • DIY installation
  • Liner: 60 mils

Main Advantages

  • High flexible recyclable membrane
  • Can be used for new roofing work and re-roofing work
  • Low temperature sustainability
  • Reliable water-proof properties

Lottes Roofing Roofing Underlayment

Roofing Underlayment from Lottes

If longevity of the roofing underlayment is the criteria for you to choose the product, then this Lottes TPO White Roofing Kit, should sit at the top of your selection.

Manufactured in USA by Johns Manville, the no.1 TPO rubber manufacturer of US, this roofing underlayment comes with a 10 year off the rack warranty.

Instead of EPDM rubber, this product uses TPO rubber which makes it extremely pliable while you apply it on your roofing deck. By virtue of the type of raw material used, it is naturally weather resistant. With a thickness of 45 mils, it is puncture resistant and this makes it a great buy. The polyester reinforcement fabric gives it a wider protection against strong winds.

This underlayment comes with a grey bottom and a top while layer coating with double thick scrim support. With all its structured durability, the underlayment is lightweight weighing to just 2.7 pounds per square feet.

The TPO rubberized membrane is resistant to strong windy situations, excessive rainfalls, and high sun exposure. The insulation ensures its protection against over heating and strong UV rays.

The Lottes TPO underlayment is designed for DIY application. It can fit into a wide range roof decks and surfaces like plywood, cedar, metal, OSB, BUR, and polyurethane induced insulation like TPO & PVC.

The TPO induced layers are designed to offer greater installation flexibility like that of welding and other such modifications. The product comes with an option for adhesive application and is useful for planning your flash system.

Features

  • Pack Dimensions: 36 x 18 x 18 inches
  • Sheet dimensions: 10 x 15 inches
  • Thickness: 45 mils
  • TPO rubberized membrane
  • Solid white coated top layer

Main Advantages

  • Tear resistant
  • High wind resistant
  • Pliable material used
  • Punctures resistant
  • Polyester fabric reinforced
  • Compatible with many roof surfaces

Owens Corning ProArmor Synthetic Roof Felts

Owens Corning 736642 Synthetic roof felts

 

Homeowners having shingle roofs of asphalt will find it very beneficial in installing an underlayment which has been designed particularly for such roof surfaces. Such a match has the ability to provide a good fit, increased performance owing to higher compatibility and a reduced price per square feet.

The Owens Corning company manufactures this particular synthetic felt specifically for asphalt shingle roof surfaces. Being compatible in its design, the underlayment brings performance consistency throughout its surface coverage and along each and every seal.

Compared to the traditional fifteen pound underlayments, this felt syntehtic based underlayment is very much water resistant without adding any weight to itself. Due to the marked fastening and its light-weight feature, it is easy to install.

The trademarked Fusion Coat Tech along with the non woven surface gives this underlayment a great walking condition even on steep slope shingle roofs.

The light gray coated top surface has an ability to withstand 30 days of direct exposure. The inner insulation gives protection against windy rain, ice and rough weather conditions.

Features

  • Dimensions: 42 inches wide
  • Length of rolls: 286 sq. ft. / roll
  • Synthetic felt
  • Designed specifically for asphalt shingles
  • Covers 9.29 sq. ft. per roll with a 3 inch overlap
  • Weight: 25 pounds

Main advantages

  • Water-proof
  • Easy to install
  • Walk friendly trademark technology
  • Dual surface system
  • Fire rating: Class A

GAF 0973 Roofing Felts

 

GAF 0973 Roof Underlayment Felts

 

GAF has been manufacturing accessible and durable roofing felts for many years now. They have been the go to product for many homeowners for reinforcing their home roofs over the years. A reliable and dependable name, they have been in the roofing underlayment sector for quite a long time.

Quality in roofing underlayment is important to prevent wind-induced rain from getting under the shingles and to cause potential damage to the interior and the structure of the home. The regular asphalt felt material tears easily & result in moisture absorption which in turn leads to to wrinkles in the shingles.

Induced with #15 and #30 asphalt felts, this GAF FeltBuster roofing underlayment with High-Traction Synthetic feature is absolutely un-tearable. It will not not absorb any moisture, and hence prevent wrinkling of the shingles.

This underlayment product stands out for its enhanced and safe walk-on feature. This enhanced walkability is further combined with a cooler upper surface (compared to black asphalt felts). It has a temperature difference of almost 30 degree Fahrenheit when compared to regular black felts which retain more heat.

This product is participatess in the GAF Warranty for Roofing System. This trademark FeltBuster Synthetic High-Traction Roofing Felt comes with a limited lifetime warranty. The only condition is that it should be installed on shingle roofs with similar warranty. Composed of non asphaltic polypropylene, this synthetic felt underlayment is tear resistant and pushes moisture back.

Due to its inherent design and superior build quality, this product from GAF, fits better on the deck, removing any remote chances of wrinkling, and creating a more presentable & desirable look for your roof. Its lightweight design is very suitable for DIY installation.

Features

  • Dimensions: 48 inches
  • Length of each roll: 250 square feet
  • Better polypropylene construction
  • Cooler temperature on the surface
  • Tear-resistant design
  • Weight: 30 pounds

Main Advantages

  • Great Walkability
  • Surface temperature lower by 30 degrees Fahrenheit (against black felts)
  • Lightweight design
  • Reliable service
  • Life time warranty (with conditions)
  • Repels moisture
  • Corrosion-free material

LL-120 Series SuperLock Roof Underlayment

Roof Underlayment LL-120 Series SuperLock

For homes which consistently and continuously face the issue of strong winds and changes in weather conditions every now and then, the Superlock LL 120 series is a perfect fit for their roofing underlayment needs.

While almost every roof underlayment is designed to save your roof from strong gush winds, some products like the LL 120 series Superlock synthetic roofing underlyament is built specifically for this purpose only. It can stand against severe wind gushes without batting an eyelid.

Apart from being able to resist strong forceful winds, it is also able to prevent any significant tearing and blow offs.  It is technically a sound product, resists & repels water thereby making it virtually waterproof, and eliminates leakages in your roof. In the process, the roof is not exposed to surface bristling which often happens at low temperatures. This keeps your home safe from weather induced damages.

This roof underlayment is recylable making it environment friendly. If you are an environment conscious person who would not want to leave unnecessary carbon footprint arising out of your roofing work, then this GAF LL 120 Superlock series will surely fit into your idea of a good roof underlayment.  It is made out industrial grade recycled polymers and is resistant to molds too.

Its non slip surface traction gives the foot a firm grip on the steep roof slopes also. The underlayment also has a anti-slip bottom coating to keep it secure under powerful strong windy conditions. It will never slip or shift from its original placement.

Features

  • Width: 4 inches
  • Length: 250 feet
  • Anti-slip coating in the underbelly
  • Anti-skip feet design
  • Repels moisture

Main advantages

  • Industrial grade recyclable material
  • Resists oil leaching
  • Does not absorb moisture
  • Remains brittle-proof even in low temperature
  • Enhanced foot surface traction
  • Extra bottom layer coating to prevent skidding of the underlayment

Info Section

Types of Roof Underlayment

The industry currently offers a a variety of insulation options for roof underlayment. Most of these products can be classified into 3 main categories

  • Asphalt saturated felt
  • Non-bitumen synthetics
  • Rubberized asphalt

Asphalt Saturated Felt

Among the most traditional type of underlayment in the market, it used to be the default option for commercial applications before the advent of non-bitumen synthetics and rubberized asphalt. The asphalt saturated felt is manufactured with refined crude residue which prevents formation of resin stains on wood and acts as a waterproofing agent. The use of this kind of underlayment is now limited to homes in areas with temperate weather conditions.

Rubberized Asphalt

This actually is a misnomer. Inspite of the this underlayment being referred to as rubberized asphalt, it actually does not contain any asphalt in its composition. It is available in various combinations and compositions, containing rubber like stuff in a sheet form. Mostly, the rubberized asphalt underlayment is fixed with either external or self adhesives instead of the traditional method of nails.

Due to its extra ordinary flexibility, the rubberized asphalt underlayment is the best option for roofs which are exposed to extreme changes in climate temperature. This product can also be modified and enhanced to suit specific roof requirements like sound insulation, adding layers for waterproofing, and fiberglass type reinforcement.

Non-bitumen Synthetics

For the last few years, non-bitumen based synthetics have emerged as the most preferred insulation type for roofing underlayments. More often they are also referred to as Synthetic Felts. They are made of thermoplastics like polypropylene or polyethylene. The biggest advantage of using a synthetic underlayment is the extra ordinary flexibility and strength the product brings to the roof. They are resistant to mold and water by virtue of being synthetic in nature.

The former quality of being mold resistant, is also a long term asset for construction or repair work in the sense that the material can be left exposed to air for longer duration without the risk of it being run over with mold. Many roofing structures have synthetic felts as the default roofing underlayment material; the most common brands being CertainTeed and GAF.

Each of the above categories of roof underlayments have a range of products designed for different roofing applications. While some are manufactured for specific climatic conditions, others are crafted as per roof compatibilities or for specific roofs like metal roof, shingles, wood.

Self adhesive roof underlayment

This is the most popular choice among the home owners. Such type of underlayments are not compatible with all kinds of roof material. You should select this only when your roofing and this self adhesive underlayment are compatible with each other. This kind of underlayment generally goes good with asphalt shingles, steep slope roofs, metal roofs, and tile based roofs.

They are also heat resistant and are considered reliable roof protectors against harsh and extreme climate temperatures. The installation is pretty much DIY where the self adhesive feature allows you to directly install the underlayment on the deck of the roof without having the need of roofing nails.

Waterproof roof underlayment

These are better choice in wet and rainy climate. You will come across two types of roof underlayment – water proof and water resistant. There’s a difference between the two. Generally, one should prefer for a water proof roof underlayment if you often experience rainy conditions in your area.

Rubber roof underlayment or Rubberized asphalt

As discussed earlier, a rubber underlayments may not contain any asphalt component. Infact, most modern rubber asphalt underlaymnets avoid asphalt as a component of this product. They are made of recycled high grade rubber, polyester, and polyethylene which gives this product durability and high flexibility.

Rubber roof underlayments are water proof and have a greater heat resistant capacity. The pliability of this underlayment makes it the preferred choice for odd shaped roof coverings also.

Tile roof underlayment

Tile based roofs always require sufficient level of underlayer protection which is generally provided by felts. Earlier, the general practice was to get a 30 pound felt applied to the tile roof. But this would always result in deterioration of the roof, prematurely. It would create droughts and leakages and eventually lead to disintegration of the roofing underlayment.

But now things have changed. Tile roof underlayments are now reinforced with stronger and better felts, the 40 pound felt being the greatest example. As against the 30 pound felts, the new ones mix asphalt and rubber to increase the strength and resistance levels of these felts to guard against extreme weather conditions.

Slate roof underlayment

Many roof contractors prefer traditional old type Felt installation for slate roofs. The most common preference being for the 30 pound felts. Depending on the roof specifics, budget, climate and living conditions, the underlayment that you might choose could be asphalt saturated or just modern day rubberized felts for extra durability.

Some slate roofs are subjected to double thick underlayments to factor in heavy rains.

Water & Ice Roof Underlayments

Homes in areas with extreme winter conditions may experience issues of ice related damage to the roofs. Excessive snow, rain, and reformation of ice damages the roofs, causes strain and results in internal damages and leaks due to water.

These type of underlayments are specifically crafted to protect your roofs from icy and low temperature weather conditions. The durable and strong insulation in these underlayments protects your roof from harsh icy weather. These are made of polymer induced modified bitumen which gives them their famed durability.

Also referred to as Snow & Ice shields, they contain a reinforced membrane which gives insulation to your roof to create strong resistance against water and ice.

Titanium roof underlayment

It is generally synthetic and has 15 mils of average thickness. Titanium underlayments are enhanced with special layers to get the finish of anti slip surface. This is why they are rough on both the sides. They are good for roofs with shingles, shaker style roofs, and metal roofs.

Asphalt single roof underlayment

Hot temperatures have their own set of risks associated with them. Such asphalt shingle roofs are subjected to increased temperature and higher levels of humidity, damage due to vapor and UV. It is for this reason that they require an extra level of vapor barrier sandwiched between the roof deck and shingle layers. You can also place an ice and snow underlayment for extra security of the roof.

Flat roof underlayment

Low slope and flat roofs are generally better compatible with rubber underlayments. Due to their inherent flexibility, they make for a great fit of such roof designs. The rubber underlayments are also capable of protecting the roof against rainstorms and strong gusty winds.

Steel / Metal Roof underlayment

Metal roofs, steel roofs, and steel slope roofs should be reinforced with Felt underlayments which have non-perforating structure. They also contain asphalt as a component. The felt can either be synthetic or organic, depending upon the specific requirements of each roof. Though the synthetic roof underlayment will be a little more expensive, it will add durability to your roof structure.

Roof Underlayment FAQ

Is it necessary to do roof underlayment?

Doing a roof underalayment is not always required, but you must consider the weather conditions your roof is going to be subjected to. If it is going to bear high summer heat and humid climate or harsh winter temperatures, you should consider having a roof underlayment work done. Even if your home is located in a moderate climate area, you should apply an underlayment to the vulnerable areas of your roof to avoid damage from rains or occasional strong winds. Roofs with low slopes must install an underlayment.

Which is better- syntehtic roof underlayment or felt underlayment

This is the biggest debated question among the home owners and contractors for roofing underlayment, the question of Synthetics vs Felts. The general term for all roofing underlayments continues to be “roofing felt”. This is so because the earlier commercially used material was the asphalt saturated felt. And this is how the word has stuck to popular roofing vocabulary. And it becomes natural to assume that felts are the most preferred and used form of roofing underlayment.

While the felts continue to be the most commercially demanded and sold roof underlayment, their synthetic counterparts have consistently been seeing a rise in demand over a period of time.  The synthetic felts are more suitable to certain kinds of roofs and perform better in harsh climatic conditions. Now, the question arises as to how to know which one among the both is better for your roof ?

It will be judicious to do a cost benefit analysis for each of them and weigh it against your roofing requirements.

Traditional felts

  • Trust worthy choice of contractors
  • Organic and pocket friendly priced
  • High compatibility with most used materials
  • Ease of install for all kinds of roofs

Synthetic Felts

  • Sturdy and light-weight
  • Supremely resistant to harsh weather elements against the traditional felts
  • Mostly have UV protective feature
  • Resistant to bristling & molds
  • Generally priced above the traditional felts

What you choose will depend upon a host of factors – budget constraints or budget availability, type of roof, climatic conditions, topography of your house like whether it is located on a hill, or in a densely populated area, availability of open area around your house so that you can judge if the flow of air is going to be low, moderate or high and precipitation levels in your area.

It is important for you to be receptive of ideas and suggestion and consult a roofing professional to arrive at a decision whether you would want to apply a synthetic roof underlayment or a traditional roofing felt.

Are all roof underlayments waterproof ?

Not all underlayments are waterproof, but almost all of them are water-resistant. The tar felt paper in the traditional underlayment acts as the water proofing membrane. Whereas synthetic underlayment contains fiberglass fleece or a polyester layer rinsed in a waterproofing chemical.

You must differentiate between a water proof and a water resistant underlayment. A water resistant underlayment will run the risk of leaks and should not be treated as sure shot water barrier.

Is synthetic roofing felts breathable ?

The breathable factor of synthetic felts is determined by its perm rates. Synthetic felts with a perm rating of 0.1 are non-breathable, they act as vapor barricades with a little bit of permeation. For a synthetic felt underlayment to be breathable, it should have a rating of 9.5 which will allow permeation and give the material a breathable factor.

Can roofing felts hold the rains back in the roof ?

Most traditional felt papers are crafted to stand against wet atmosphere with normal rain intensity. However sustained & continuous exposure to rainy conditions beyond few days can result in disintegration of the underlayment material.

Are breathable roofing felts water-proof ?

Almost all breathable roofing underlayments are water resistant if not water proof. They use water-proof membrane systems which are also able to resist dust and snow along with maintaining a degree of permeation. Look out for specific water proof feature in the product if you are actually looking for it.

What safety points are to be remembered while doing roof underlayment ?

Before you start a roof underlayment work, it is advisable to equip yourself with the local construction codes and safety laws in your area. You must ensure that you in sync with the local standards and that safety of everyone involved has been thoroughly considered.

If you are hiring a contractor, ensure to read the contract carefully and insist that the contractor has taken an insurance for everyone involved in the project.

Safety tips 

  • Please use fall protection systems & devices when executing any roof jobs. You can either purchase or rent footwear which can secure traction on the roof. Your walking on the roof surface should be with all the safety and security standards.
  • Synthetic roof underlayments should always be fastened, with 1 inch plastic nails, to the deck, before you can allow any contractual worker to walk on the roof surface
  • You should install support platforms and roof jacks when working on steep slope roof. All materials to be used in the roofing should be secured on the toe board or the storage platform. This will prevent the roof materials from falling off and causing any kind of damage.
  • Keep the ladder safety regulations and standards in mind to ensure safety of all hands working on your roof project. This will also mean to keep the ladders safely secured in designated places so that they do not come in any kind of contact with overhead wires and power lines.
  • Check the weather forecast and keep track of any changes such as strong winds, precipitation, thunderstorms, and other sudden climatic changes. Each of them pose a danger to you and your workers.
  • Avoid working for long hours in high, hot and humid temperatures. Humid conditions cause a lot of dehydration and exhaustion which can lead to heat strokes. Keep yourself and everyone around you well hydrated.
  • Clear the roof of all debris completely before you initiate your work. Once your project is over, please ensure to remove all tools, materials, and debris arising out of your project. If you are in a coastal area, be sure to clear the debris per the coastal regulations.
  • Check if the underlayment has incurred any kind of damage during the installation. Certain materials might have been damaged due to harsh weather climate conditions during the installation or the storage process. Repair if you come across any damage.

How to install synthetic underlayments

  • Most synthetic roofing underlayments act as vapor barricades. It is good to install them above the attics with sufficient ventilation.
  • During the application, the roof’s deck should be dry, clean and free of debris & ridges. Cut the underlayment as required using a sharp edged tool or knife.
  • You should install the drip edge, along the eaves of the roof. Place the synthetic felts horizontally, bringing it in line with the eave. In order to cover the drip edge, ensure that the over hang is at least 1.5″
  • The material should be laid in a manner where the anti-skid printed side is up. Start working from the lowest roof point of the eave and move up. Cover the material with two metal rake edge for trimming. Ensure that you roll the underlayment material without causing a stretch.
  • While you have laid the material, focus on the over lap it has created. The overlap depends on what is the pitch of the roof. A pitch of 3:12 or more will need a minimum of 4″ horizontal overlap for the upper course against the lower course. The vertical will be a minimum of 12″ allowance. A pitch in the range of 3:12 to 1.5: 12 will need a minimum 6″ horizontal overlap for the upper course against the lower course. The vertical will be a minimum of 20″ allowance.
  • Always use only the 1 inch diameter plastic nails for roofing underlayment purpose. This nail size should be followed for both machine and manual nailing. Drive each of those nails at 90° till the head of the nail is secured against the underlayment.
  • The vertical overlap allowance of the roll is decided by the pitch of the roof. As discussed earlier, it will be in the range of 12 to 20 inches. The application has to be per the required rate of the roof.
  • If the underlayment material is not self adhesive, then you can use butyl rubber tape for roofs or asbestos free plastic cement to fill the in-between seams. This will prevent damages to the underlayment material if they are exposed for a long duration during the construction or repair period.
  • If the materials have self adhesive feature, you should nail them down, if the winds are strong. This will keep the material secure and will prevent them from being damaged.
  • A good strategy is to apply a single uncut roll to the valleys & hips of the vertical length of the center of the roof surface. And then knit the material in a horizonal manner across the hips and valleys.
  • Please ensure that the underlayment is secured in its place before you start putting in the battens. Avoid drilling nails at places where they obstruct the battens.

Should you install a drip edge before a tar paper ?

It is advisable to install it in a way where it is placed over the paper felt around the eaves and below the underlayment material with the rake.

How should a roof underlayment cost ?

The cost of a roofing underlayment depends upon durability, features, type and base material. On an average, a roof underlayment will cost around $4 per square feet and depending upon other factors can go upto $5 to $6 per sqaure feet.

Conclusion

A roof underlayment should be looked at as a basic requirement to keep your house & your family safe and secured from the effects of weather conditions. It is no more a discretionary spend item on the house. Irrespective of your choice, both synthetic and organic underlayments have proven durability in actual field applications and come with long term warranties to safeguard the value of your money spent on it.

About the author

Megan

Megan is a passionate home innovator with 20+ years of experience in home improvement industry. She works as an assistant in a home improvement store in her city. Creating innovative home solutions is what keeps her active in her "me time".

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