Roof layers: what's under the shingles (2023)

FAQs

What layers go under shingles? ›

What Is Roofing Underlayment? Roofing underlayment is what lies between the shingles and the roof sheathing, or roof deck, which is typically either plywood or OSB. It's installed directly on the roof deck and provides a secondary layer of protection from the elements, including rain, snow, and wind.

What is roofing felt paper? Sometimes called roofing felt underlayment, roofing tar paper, or roll roofing, this is a layer of protection installed between the roof deck and the roofing shingles.

What Is That Shiny Plastic Film Strip On Shingles? Sealant protection… GAF adds a thin plastic film to keep the sealant from activating while in storage and shipping. This film is protecting the shingles from sealing together while in storage but does not align with the sealant adhesive when the shingles are installed.

Underlayment. This felt, or rubberized asphalt sheet, provides an extra layer of protection between your shingles and your roof deck. It helps reduce blow-off by allowing your shingles to lay flatter and more uniformly.

One question that people often ask is whether or not an underlayment is required beneath asphalt shingles. In general, it's a good idea to use underlayment under any type of roofing, including shingles.

Decking. Also known as the wood sheathing, this is the base on which everything else is laid on. It's essentially the foundation of the roof. This is typically made with OSB or oriented strand board or plywood that's attached with nails onto the rafters.

Aside from shingles and underlayment, plywood decking is one of the most important components in your roof. The plywood decking is integral in keeping your home free of unwanted water and mold. If the plywood has gotten wet, it can have a disastrous effect on the rest of your roof, especially the shingles.

Gravel Layer: Also known as the frost blanket, a mixture of gravel and sand is laid to eliminate the effects of freezing and thawing temperatures. Base Layer: Using bitumen, cement or lime as the predominant binder, a bound base course is laid over the unbound base course.

In general, there are three types of roofing underlayment: felt, self-adhered, and synthetic. Each has its own benefits and advantages, and the type you choose generally depends on what your roofing contractor is comfortable with and your local building codes and regulations.

One of the most common types of underlayment used in residential, steep-slope applications is black, ashphalt-saturated felt paper. Felt underlayment may be made from either organic or fiberglass substrate, although the organic is much more common. It's called "organic" underlayment because it has a cellulose base.

What is the black stuff under roof shingles? ›

Gloeocapsa magma commonly grows on asphalt shingle roofing because it eats away at the shingles' limestone fillers.

Roofing felt or felt paper, also called underlayment or roofing tar paper, goes between the roof deck and the shingles, which adds another layer of protection to your roof. Underlayment has a base made from natural materials like wood cellulose, or synthetics like fiberglass/polyester.

Two layers of underlayment are required for low-slope roofs. The first course is doubled. Above that, 36-inch wide strips are then applied to the roof in a shingle fashion, starting at the lower roof edge, and overlapping subsequent courses a minimum of 19 inches.

A: It is never a good idea to install a roof over wet plywood or any type of roof sheathing. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the steam finally escapes.

The membranes are designed to form a watertight seal around the nail penetrations when shingles are applied. Potentially, covering an entire roof with ice and water protector can prevent leaks even after high wind conditions blow shingles off the roof—preventing further damage and making repair easier.

Many homeowners don't realize that roofers install a thin layer of felt on the plywood prior to putting down the asphalt riding shingles. This boring layer of black felt, sometimes referred to as tar paper, may not be much to look at but is a crucial step to properly installing a new roof.

That backed-up water can get under the shingles and leak inside. Ice dams can form in as little as 1 or 2 inches of snow. "It's hard to do anything about them after the fact," Crowe says.

Plywood will absorb moisture quicker than OSB, but consequently it will also dry quicker. Both products will swell when wet, but plywood will return to almost its exact shape when it dries. OSB is less forgiving of being left out in the rain and will show more deformities after a wetting and drying cycle.

What Is a Soffit? Your roof by necessity, will often times extend over the walls of your home. This overhang can go by a few names, such as the house eaves or the rafters of your roof. The underside of this overhang, when given a finished appearance, is known as the soffit, which means “something fixed underneath”.

Do you need ice and water shield under shingles? ›

Its main purpose is to protect your roof decking if water gets underneath your roofing material (asphalt shingles, metal roof, etc.). It's crucial to have ice and water shield installed on/around certain areas of your roof, like roof valleys, around penetrations, and on roofs that have a 2/12, 3/12, or 4/12 pitch.

Most Common Thickness

The most common rafter spacing is 24 inches, and 5/8-inch plywood is recommended for that. It will support roof loads for most situations and is the standard for most roof applications. Roofs with very heavy loads may require 3/4-inch thickness.

Each plywood sheet is 4 x 8 feet or 32 square feet, which coincidentally is almost exactly equivalent to the coverage of one bundle of traditional three-tab shingles.

The secret to having the best asphalt driveway is by having a solid base. Using quality crushed gravel as a base to your blacktop will surely give you the perfect driveway quality that will last for a very long time.

Subgrade. Once the dirt is prepared, contractors lay down the subgrade. The subgrade is the most important part of the entire design, setting down the very foundation of the pavement.

Keep in mind that the gravel base under the blacktop is where the driveway gets almost all its strength. You want at least 8 inches of crushed compacted gravel under the blacktop.

For roofers, Synthetic Roofing felt is much safer during installation because there is a gripping surface that prevents slipping or falling. Tar paper and roofing felt are somewhat similar in that they both shed water.

Asphalt shingles are popular because they blend looks, longevity, and a reasonable price, and they're typically the easiest to install, saving you money on labor costs as well. Specialty roofing materials like slate, tile, and metal tend to cost much more, but they can also last much longer—and they look nicer.

With that in mind, synthetic underlayment is more durable than felt underlayment. Felt underlayment is much more prone to rip from high winds and during the installation process. Synthetic underlayment also holds nails better and repels water instead of absorbing it.

Non-bitumen synthetic roofing underlayment is known for being highly flexible, waterproof, durable, and mold-resistant. Compared to rubberized asphalt, synthetic underlayment is exceptionally lightweight.

What is a good thickness for underlayment? ›

It comprises padding materials and is typically about 1/4 to 1/2 inch in thickness. The purpose of the underlayment is to provide a sturdy yet comfortable layer for your outer flooring to sit on. Underlayment can be made of wood or even cement, but most often is some type of foam padding.

Screws are preferred over nails for subfloor and underlayment installations as they provide strong and tight connections that help prevent the floor from squeaking. Before starting your next subfloor or underlayment installation, make sure you have the right subfloor screw gun for the job.

Answer: Roofing felt is a layer of tar paper installed beneath the shingles to provide a backup waterproof membrane in case of leakage. Felt, otherwise known as underpayment, is required when asphalt shingles are installed as a first layer of roofing or when they are applied over wood shingles or a built-up roof.

Are Roof Shingles Toxic? Modern shingles can be toxic during installation, but they will usually not be harmful unless you're trying to collect potable rainwater from the roof; chemical constituents in the shingles can find their way into the run-off water.

Roof Moss Killer is used to effectively remove moss and kill growth spores quickly. It is the preferred product used by commercial roof cleaning companies throughout the UK.

For roofs with slopes of 4:12 or greater, one layer of underlayment is required. For roofs with slopes between 2:12 and 4:12, 19” laps of underlayment is required, starting with a 19" strip, then full sheets.

Asphalt felt, the most common type of underlayment has a lifespan of between 20 to 30 years. However, in extreme extended conditions, its lifespan can be cut by half. Fortunately, new rubberised or synthetic asphalt underlayment has a longer lifespan of between 25 and 35 years.

For ridges, the underlayment should … be lapped over the ridge at least 4” (102 mm) to 6” (152 mm) as would be done on a new or complete tear-off installation.

Underneath all the shingles and underlayment has a layer of plywood decking. That layer is the last line of defense between the inside of your home and the outside world. Eventually, the underlying plywood decking may need to be replaced, here's what you should know about it.

Felt underlayments are usually made from synthetics such as fiberglass or natural materials like wood cellulose. They're then layered with a protective asphalt coating to defend against debris and moisture. This is a traditional underlayment option for cedar shingles.

What are the three layers on a roof? ›

And when you do replace your roofing, there are three main layers that have to be addressed: the roof deck, underlayment, and the shingles themselves.

In most states, you're only allowed to have 2 layers of shingles on a roof for fire safety reasons. However, you'll still see roofs that have 3 or 4 layers today. If you already have 2 or more layers, a contractor will recommend a full replacement.

Synthetic Underlayment

This is currently the most popular choice for roof underlayment, and with good reason. Made with an asphalt-saturated basemat and fortified with a mix of fiberglass, this product is not only extremely water-resistant, much stronger and more resistant to tears than other types of underlayment.

Roofing felt or felt paper, also called underlayment or roofing tar paper, goes between the roof deck and the shingles, which adds another layer of protection to your roof. Underlayment has a base made from natural materials like wood cellulose, or synthetics like fiberglass/polyester.

Underlayment— This is the first layer of waterproofing that goes down in between sheathing and shingles. Underlayment seals the roof from damaging elements like snow, ice and rain. Also referred to as a membrane, underlayment is mandatory for providing the roof with a waterproof barrier.

The Silicone Roof Sealant

Silicone roof sealant is also a great option to fill in shingle cracks and leaky nail holes and is also used to repair folded or slightly lifted shingles. A small, droplet-like amount of silicone will have to be placed with a caulk gun under the bent part of the shingle.

Without a drip edge, water may end up beneath the shingles and may cause damage to various parts of the home. Though your home may not have originally had a drip edge installed, drip edges are now required by most building codes across North America to protect homes from damage.

Shingles should be installed over the drip edge a minimum of 3/8” (9 mm) at both the eave edge and the rake edge. If the drip edge extends… out from the rakes and eaves (typically called DL Style or D Type), the shingles may be installed flush with the drip edge.