Roofing 101

Roofing FAQ


There’s No Such Thing As A Silly Question

Here you can see popular questions that homeowners have asked about their roofs over the years. Chances are good you’ll find an answer to your question in this helpful roofing shingles guide and FAQ page. If you can’t find what you need, help is just an email or a phone call away!

The following links, when selected, will provide information to frequently asked questions.

NOTE: Some of the information in this section is based on the technical bulletins published by the Asphalt Roofing Manufacturers Association (ARMA) and the “Canadian Asphalt Shingle Manufacturers” Association (CASMA).

FAQ’s About

For a glossary of residential roofing terms, click here.

Selecting A Shingle:

Q: What are the most common asphalt shingle product and test standards?

A:  The most commonly found product and test standards are:

  • ASTM E108:  “Fire Tests of Roof Coverings” and ULC S-107:  “Fire Tests of Roof Coverings” are tests for roofs exposed to exterior fire hazards.  Roof coverings are rated as Class A, B or C.  Typically, glass shingle roof systems are Class A (including the underlayment). The Canadian equivalent for this requirement is ULC-S107.
  • ASTM D3018: “Class A Asphalt Shingles Surfaced with Mineral Granules” is a product standard with some tests for Class A glass roof shingles.
  • ASTM D3161: “Standard Test Method for Wind-Resistance of Steep Slope Roofing Products (Fan-Induced Method)” is a laboratory wind test.
  • ASTM D3462:  “Asphalt Shingles Made from Glass Felt and Surfaced with Mineral Granules” is a product standard with requirements for glass shingles.  All IKO glass shingles comply.
  • CSA A123.5-M:  “Asphalt Shingles Made with Glass Felt Saturated with Mineral Granules” is a product standard with requirements for glass roofing shingles.  All IKO glass shingles comply (except Marathon 20)

Note: Make sure that shingles purchased or used meet the required standard.

See CASMA Technical Bulletin No. 5 for more information.

Q: Do IKO shingles meet the Canadian building code?

A:  All IKO roofing shingles sold in Canada meet the Canadian building code.

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Installing Shingles:

Q: Why/when should I use an asphalt shingle underlayment?

A:  An asphalt shingle underlayment is typically dry felt that may be impregnated or coated with an asphalt saturant, or a synthetic sheet.  The use of an underlayment is recommended for the following reasons:

  • Resins may exude from the wood board decking.  Underlayment protects roof shingles from the resins that may be released.
  • Underlayments protect decking material from wind-driven rain that may penetrate the shingle layers.
  • To validate their limited warranties, many manufacturers require the use of underlayment.
  • The use of underlayments, particularly heavier grades, reduces “picture framing.”  According to CASMA, picture framing is the visible outline of deck panels caused by irregularities in roof decking thicknesses.
  • To obtain a Class A fire resistance rating, underlayments should be used underneath shingles.
  • The underlayment should conform with CSA 123.3-M (No. 15 / ASTM D226 Type 1 No. 15 felt), ASTM D 4869,  and/or CAN 2-51.32 (Breather Type Sheathing Paper) industry standards.

See CASMA Technical Bulletin No. 3 or ARMA Use of Asphalt Shingle Underlayment Form for more information.

Q: Can I apply new shingles over existing shingles?

A:  Yes.  You can apply new shingles over existing shingles, depending on the condition of the roof.  If the roof has one layer of shingles that are lying flat and the deck is in good condition, the existing shingles typically do not have to be removed. Check with local officials to make sure that building codes are being followed.  During re-roofing is a good opportunity to examine roof ventilation to ensure vents are sufficient in number, positioned properly and are unobstructed.

See CASMA Technical Bulletin No. 6 or ARMA Re-roofing: Tear Off vs. Re-Cover Form for more information.

Q: What offsets should be used for laminated shingles?

A:  For laminated roofing shingles, IKO’s recommended offset is 10 inches.   Regardless of the shingle type, it is always best to follow all application instructions printed on the shingle package.  This will ensure proper roof performance and finished roof aesthetics.  All roofing shingles must be applied with a minimum offset no less than 4 inches.

Q: How can I ensure proper performance from shingles in cold climates?

A:  Proper performance from shingles installed and used in cold weather can be achieved by following the recommendations listed below:

  • Make sure that the roof is properly ventilated.
  • Be careful when using shingles in cold weather.  They tend to get brittle and may crack or break.  Try not to throw, drop or bend shingles.
  • If you are in an area that experiences freezing winter temperatures, eaves protection should be used to reduce water damage from ice dam formation.  Use self-adhering eave protector membranes
  • Hand seal asphalt roof shingles in cold weather with an asphaltic cement recommended by the manufacturer.
  • When applying ridge caps, keep the shingles that are being used as ridge caps in a warm place so that they will be flexible enough to bend.
  • When re-covering an existing roof with new shingles, make sure that the old shingles are flat.
  • In areas that receive high amounts of snowfall, try not to damage shingles when removing snow.  Damage caused by snow removal is not covered under our limited material warranty.
  • Use caution if walking on a roof in the winter time.  The sealant bond between shingles can become quite brittle in cold weather.  Therefore, traffic on the roof may cause sealant bonds to break.

See CASMA Technical Bulletin No. 8 for more information.

Q: Which type of fastener should be used to install asphalt shingles – nails or staples?

A:  IKO agrees with and supports the ARMA position that nails are the preferred method of fastening asphalt roof shingles due to their superior holding strength.  The following fastening tips apply to most IKO shingles; (check specific product application instructions for further information):

  • A minimum of four fasteners per shingle are used.
  • Correctly place and position fasteners below the sealant strip, but above the cut-out on three tab shingles, and in the nail line on laminated shingles.
  • The fasteners must be straight and flush with the surface of the shingle, not sunk into the shingle or sticking up at any point.
  • Make sure there is correct penetration of the deck as specified by ARMA and the NRCA.

See the technical bulleting from ARMA Nail Application of Asphalt Strip Shingles for New and Recover Roofing Form for more information.

Q: Do I need to peel the release tape off the shingles?

A:  The plastic release film on the back of IKO roofing shingles does not need to be removed. The sole purpose of this tape is to prevent the shingles from sticking together in the package.  Once the shingles have been removed from the package and are applied in the correct orientation on the roof, the release tape serves no purpose whatsoever.  The shingle sealant, which bonds the shingles together, is located elsewhere on the shingle and will seal succeeding courses of the shingles together on the roof when warmed by the heat of the sun, soon after application.

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Shingle Performance:

Q: What is causing the algae growth on my shingles?

A:  Algae growth exists as a brown to black discoloration of the shingle and is caused by a blue-green algae known as Gloeocapsa. Although algae may exist on a shingle, it does not affect the functional performance of the shingle.  Essentially, this is an aesthetic problem. Most IKO roofing shingles are now algae resistant, and covered by a Limited Algae Resistance Warranty.

See CASMA Technical Bulletin No. 13 or ARMA Algae Discoloration of Roofs Form for more information.

Q: How do I get rid of the algae growth on my shingles?

A:  There are several ways to reduce the discoloration:

  • For a new roof, install a zinc or galvanized type metal near the ridge of the roof.   As the metal ions are oxidized and erode off of the metal strip, they wash down the roof inhibiting cellular algae growth.
  • A dilute solution of chlorine bleach, trisodium phosphate and water can be applied – one part chlorine bleach to three parts water with a quarter cup of trisodium phosphate.   Note:  Trisodium phosphate should be available at any paint supply store.   Gently spray the solution on the shingles.  For stains that are hard to remove, scrub mildly.  Scrubbing too harshly will remove granules.  Rinse the shingles thoroughly with water.  In the past, this has been a temporary solution and usually needs to be repeated every couple of years.  Apply this solution carefully to avoid damaging other parts of the building or the shrubbery below.
  • Some companies offer roof cleaning compounds or roof cleaning services.   Ensure the roof cleaning process will not damage the shingles.
  • For more information, see our article on removing moss from roof shingles.

See CASMA Technical Bulletin No. 13 or ARMA Algae Discoloration of Roofs Form for more information.

Q: Can bird excrement affect asphalt roofing products?

A:  A build-up of bird excrement on asphalt roofing products can have negative effects, if it remains on the product for a considerable amount of time. In some instances, it can even shorten the life of the roofing product. A web search may reveal companies that offer products to mitigate bird roosting/nesting on your roof.

Q: Can hail affect asphalt roofing shingles?

A:  Hail can affect asphalt roofing shingles.  The damage caused by hail can be classified into two groups:  aesthetic damage and functional damage.   Aesthetic damage results in slight granule loss and the life of the shingle is usually not affected.  Functional damage is characterized by substantial granule loss or cracking or penetration of the shingle.  Functional damage may result in short term leaks or a reduction of the life expectancy of the shingle.

According to CASMA Technical Bulletin No. 14, there are several factors that impact how roofing shingles perform in hail:

  • Size and density of hail stones – Larger heavy stones will cause more severe damage.
  • Age of the shingles – Newer roofing shingles are more resistant than older shingles, as the asphalt is less brittle and better able to absorb the impact energy.
  • Angle of hail impact – Hail which strikes the roof at a 90° angle is more likely to cause shingle fractures, while hail that strikes the roof obliquely is more likely to result in spots of granule loss.
  • Temperature – Colder temperature will be more likely to cause fractures as the asphalt will be more brittle than in warmer weather.
  • Roof deck conditions – Solid roof decks on moderately spaced trusses offer better support to the shingle surface in resisting hail damage.  Shingles on flimsy or rotted decking can be more easily fractured.

See CASMA Technical Bulletin No. 14 for more information.

Q: Are there any asphalt shingles specifically designed for hail conditions?

A: Yes, IKO’s Nordic shingles have been independently tested to the highest impact resistance, and passed the Class 4 requirements. This impact rating is solely for the purpose of enabling residential property owners to obtain a reduction in their residential insurance premium, if available. It is not to be construed as any type of express or implied warranty or guarantee of the impact performance against hail, of this shingle by the manufacturer, supplier or installer. Damage from hail is not covered under the limited warranty. For further details concerning the FM 4473 standards, visit the FM Approvals website

Q: What is buckling?

A: Buckling is defined as ridges that form along the length of the shingle, with the ridge spacing usually coincidental with deck board joints. These ridges are caused by the shingle being distorted from the movement of the deck. Buckling can occur with any deck type, but is more common with board decks, and less common on plywood/OSB decks. Buckling can occur when a new roof is installed, even if the old roof did not show any buckles; when the roof is stripped, the deck may be exposed to moisture, causing dimensional changes in the supporting lumber.

See CASMA Technical Bulletin No. 9 or ARMA Plain Facts About Buckled Shingles Form  for more information.

Q: How can I reduce the chance of having buckled shingles?

A:  The following will help to prevent buckling:

  • Apply shingles as specified by the roofing material manufacturer.
  • Make sure you have sufficient attic ventilation.
  • Decking material should not be exposed to water before or after application.
  • Use manufacturer approved wood decking materials and make sure that they are conditioned to be at moisture equilibrium with the job site environment.
  • Cover older dimensional lumber decks with a thin plywood sheathing prior to shingle installation.

See CASMA Technical Bulletin No. 9 or ARMA Plain Facts About Buckled Shingles Form  for more information.

Q: My shingles are buckling.  What should I do?

A:  There are a couple of things that you can do to correct this problem:

  • Make sure that the attic is well ventilated to reduce moisture build up.  You may need to install additional vents.
  • Remove the fasteners from the shingles that have been affected and refasten.  You may want to replace any of the buckled shingles as well.

See CASMA Technical Bulletin No. 9 or ARMA Plain Facts About Buckled Shingles Form  for more information.

Q: What is color shading?

A:  A roof observed from different lighting conditions or angles may have darker or lighter spots in certain areas.  This apparent difference in color is referred to as “shading.”  Shading is usually caused by unavoidable slight variations in texture which occur during the shingle manufacturing process.

Black or dark colored shingles are more prone to shading problems.  A small amount of light is reflected from dark surfaces.  Therefore, even slight textural differences may cause shading.  Light colored shingles reflect greater amounts of light than darker shingles and as a result it is harder to notice shading problems.  Since blends are made from a number of colors, shading differences are masked and are even less noticeable.

The material on the back of a shingle is sometimes transferred to other shingles that are next to it.  Also, when shingles are stacked too high or stored for long periods of time, stains can develop.  Both conditions can create the appearance of shading.   These are only temporary aesthetic issues and will naturally weather off.  Note:   Shading does not affect the watershedding performance or life expectancy of a shingle.

See CASMA Technical Bulletin No. 17 or ARMA Color Shading of Asphalt Shingle Roofs Form for more information.

Q: What can I do to reduce the potential for shading?

A: To reduce the potential for shading:

  • Do not mix shingles with different production codes on the same roof.
  • Make sure you follow the application instructions provided on the shingle wrapper, and also available on this web site.
  • Apply the shingles starting from the bottom of the roof and move across and up.
  • Use blended shingle colors instead of solid colors.
  • Do not stack shingles higher than what is recommended by the manufacturer.
  • Do not store shingles for long periods of time.

See CASMA Technical Bulletin No. 17 or ARMA Color Shading of Asphalt Shingle Roofs Form for more information.

Q: My gutter is filled with granules.  Is there a problem with my shingles?

A: Not necessarily. An excessive amount of granules are applied during the shingle manufacturing process to make sure that the asphalt on the roofing sheet is completely covered. It is important to completely cover the sheet with granules so that the asphalt is not exposed to ultraviolet light.

The granules are then pressed in. Due to the excessive amount of granules applied, some of the granules are only held loosely in place. Most of the excess granules are removed by the shingle manufacturing process, but some of these granules do get packaged with the shingles. These excess granules are known as “hitchhiker” granules.

“Hitchhiker” granules will typically come off during the first few years of shingle exposure on the roof. They usually will be found in gutters or at the bottom of downspouts. The loss of these granules is normal and does not affect the performance of the shingle. Granule loss only becomes a problem when much of the asphalt becomes exposed on the surface of the shingle.

See CASMA Technical Bulletin No. 18 for more information.

Q: What is fishmouthing?

A: Fishmouthing is the raising of a portion of the front edge of a shingle to create an “eyebrow” appearance. This may occur at the lower tab edge or along the cutout edge. These distortions may be more noticeable on certain roofs because of the slope, sunlight and shingle color. These “fishmouths” do not affect the life expectancy of the shingle, and they do not result in leakage, blow-off or other shingle problems.

See CASMA Technical Bulletin No. 4 for more information.

Q: What causes fishmouthing and how can it be corrected?

A:  Fishmouthing can be caused by:

  • Nails or staples that are raised.
  • Foreign matter under the shingle.
  • Wrinkled underlayment felt.
  • Damaged shingles or shingles that are bent prior to application. Fishmouths are primarily an aesthetic problem.  Typically, fishmouthing is repaired in temperate weather by sealing the shingles flat with hot melt glue.

See CASMA Technical Bulletin No. 4 for more information.

Q: What is a splice?

A: Large rolls of glass mat are used in the shingle manufacturing process, and a splice is a glued or taped lap of the end of one roll to the beginning of the succeeding roll. Rolls of glass mat must be spliced together to maintain continuous shingle production. Each splice is marked for rejection before the shingles are packaged. Occasionally, an error or oversight occurs where that splice gets packaged along with the shingles. Shingles containing a splice may delaminate on the roof, and should be replaced.

Q: What is winter curling?

A: When the front edge of a shingle tab lifts to form a shallow “U” saucer shape in cold weather and flattens when the weather is warmer, this phenomenon is known as winter curling. Sometimes, the entire front edge of a shingle may lift uniformly.

When the top surface of the shingle is cooled, this part of the shingle contracts. At the same time, the bottom of the shingle receives a certain amount of heat from the attic, especially if the attic ventilation is insufficient. As a result, the shingle curls slightly.

The appearance of winter curling depend on: the age of the shingle, whether the attic is sufficiently ventilated, the type of shingle, roof pitch, humidity and climate. Complete elimination of winter curling is rare, although the durability and watershedding properties are not affected.

See CASMA Technical Bulletin No. 7 for more information.

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Roof Types and Designs:

Q: What is a drip edge and how is it applied?

A:  Drip edges are used for watershedding at the eaves and rakes and for preventing wood materials from rotting.  It is important that the drip edge is “made of a corrosive-resistant material that extends approximately three inches back from the roof edges and bends downward over them.”  (ARMA Residential Asphalt Roofing Manual)

The drip edge should be applied beneath the underlayment or eave protection along the eaves and over the underlayment on the rakes.

Q: What are low slope roofs?

A:  Roofs that have slopes of 4:12 or less are considered to be low slope roofs.  (4:12 means a vertical rise of 4 inches for every 12 inch horizontal run, or 18.4°). Never apply asphalt shingles to slopes that are below 2:12(9.5°).  Shingles applied on low slope slopes do not last as long as shingles on steeper roof pitches, due to the increased exposure to sunlight and other weather conditions.  Generally, laminated/architectural shingles are better suited to steep roofs, where their enhanced aesthetics are more readily visible.

Q: How can I reduce some of the problems associated with low slope roofs?

A:  Low slope roofs are more susceptible to water entry due to ice dams and wind-driven rain.  Therefore, the key to a successful low slope roof is to increase the watershedding properties of the roof system.

Rain and melting snow do not run off quickly on low slope roofs.  As a result, the potential for ice dams is increased.  By providing adequate ventilation the formation of ice dams can be decreased.  Note:  “The National Building Code of Canada allows various types of ice dam membranes to be used, but CASMA recommends that self-adhering modified asphalt membranes be used.”  (CASMA Technical Bulletin No. 16)

Wind-driven rain is another concern associated with low slope roofs.  By improving the underlayment or by using a special shingle application method, the damaged caused by wind-driven rain can be reduced.

See Bulletin on Applying Shingles on Low Slopes or CASMA Technical Bulletin No. 16 for more information.

Q: I want to shingle my roof.  How many shingles will I need?

A:  By using simple calculations you can estimate the number of roof shingles that will be needed to complete the job.  Roofs come in many shapes and sizes and can be classified into simple geometric shapes such as squares, rectangles, trapezoids and triangles.  To determine how many shingles will be needed you must calculate the area of the roof.  This is done by figuring out what geometric shapes make up your roof, calculating the area of the individual shapes and summing the areas to give you the total area of the roof.  The area required is then divided by the area each bundle covers.  Don’t forget to add allowances for ridges, starter strips, etc.

See article on Estimating How Much Roofing Is Required for more information.

Q: What will happen if my roof is not properly ventilated?

A:  Insufficient ventilation can lead to:

  • Asphalt odors from hot shingles entering the home’s interior.
  • Blistering, fishmouthing, curling or premature aging of asphalt shingles.
  • Rotting of wood decks.
  • Buckling.
  • Splitting.

Proper ventilation is essential so that air movement is not restricted beneath the roof surface.

See CASMA Technical Bulletin No. 1 or ARMA Ventilation and Moisture Control for Residential Roofing Form for more information.

Q: How much ventilation do I need on my roof?

A:  The amount of ventilation needed is determined by the size and design of the roof.  For roof and attic spaces above an insulated ceiling, the vent ratio is one square foot of net free ventilating area/300 square feet.   For low slope roofs or roofs with cathedral ceilings the vent ratio is one square foot/150 square feet.

See CASMA Technical Bulletin No. 1 or ARMA Ventilation and Moisture Control for Residential Roofing Form for more information.

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General Information:

Q: Are IKO roofing products required to have Material Safety Data Sheets (MSDS)?

A:  The following roofing products do not require MSDS’s, as they are either considered manufactured articles:

  • Fiberglass Based Roofing (Shingles, Rolls, Felts)
  • APP and SBS Modified Bitumen Roofing
  • IKO Ice and Water Protectors (Goldshield[tm], StormShield[reg] & ArmourGard[tm])
  • ArmourGard Vapour Retarder
  • Protectoboard
  • IKOTherm Polyisocyanurate “ISO” Insulation

IKO does offer Material Information Sheets for these product families (downloadable from this web site), which offer similar information as one might find on an MSDS.

Q: If I have a shingle concern, what should I do?

A:  If you have a shingle concern (e.g. splice, severe granule loss, etc.), please contact the IKO Customer Service Department in your area (U.S. 1-800-433-2811; Canada 1-800-361-5836).  You will be required to submit a copy of the proof of purchase.  After verifying that the shingles purchased were manufactured by IKO, a package will be sent to you, requesting more information photos, and samples.

Q: Can I paint my roof?

A:  Yes.  The affect of paint on shingles is very negligible.  Technically, it could be argued that the paint will help the shingles weather longer.  Some roof coatings that are advertised to extend product life are simply premium quality latex paints.

Q: Do I have to use a certain type of paint on my roof?

A:  Yes. Latex paints must be used. Latex paints will do nothing more than color the shingles. On the other hand, oil-based paints may soften the shingles slightly due to the solvents that they contain. These solvents will evaporate quickly so if used carefully, there should not be any lasting effects. Generally regardless of paint used, paint weathers off of the shingles within five years. How long the paint lasts depends on the quality of the paint, the pitch of the roof, climate, etc…

Q: How are roofing shingles made?

A:  Roofing shingles are made in a continuous web process. Large rolls of glass mat are unwound and fed into the coater.  At the coater, coating (asphalt with air blown through it) is applied to the top and bottom surfaces of the sheet. Mineral stabilizers are added to the coating which improve the shingle’s fire resistance and weatherability.  Next, granules are applied to the top surface of coating.  Granules are ceramically colored crushed rock; the granules give the shingle its color, but more importantly protect the coating from ultraviolet light.  Backsurfacing is then applied to the sheet to prevent it from sticking to the machine and to other shingles when packaged.  The release tape is also applied to the back of the sheet to prevent the sealant buttons from sticking to the next shingle in the package.  The granules are then pressed into the topcoating. Once the sheet is cooled, sealant buttons are applied.  The sealant buttons allow one shingle to bond to the overlying shingle on a roof, to prevent wind uplift.  The roofing sheet is then measured and cut into shingles.  At this stage, the two pieces of laminated shingles are adhered together.  The shingles are wrapped into bundles and stored in the warehouse until they are ready to be shipped to the appropriate location.

See article for more information on what shingles are made of.

Q: What are ice dams?

A:  Ice dam formation is the result of continuous freezing and thawing of snow due to escaping heat from the house or from gutters being backed up with frozen slush.  When this occurs, water may be driven under the roof which may cause ceiling, wall, insulation and gutter damage.

See CASMA Technical Bulletin No. 10, ARMA article our IKO’s article on ice dam risks for more information.

Q: What can I do about ice dams?

A:  Ice dams can be prevented from forming by:

  • Installing a vapor barrier above the home’s warm space.
  • Insulating the attic floor.
  • Ventilating the attic.
  • Damage from ice dams, if they do form, can be reduced by:
  • Removing debris from gutters so that it does not build up over time.
  • Making sure that the outer edges of the gutters are lower than the slope line.  This will allow for snow and ice to slide clear.
  • Installing eaves flashing, such as IKO’s ArmourGard Ice & Water Protector

See CASMA Technical Bulletin No. 10 or ARMA Preventing Damage from Ice Dams Form for more information.

Q: Can I use salt to remove the ice on my shingles?

A: Yes, but there are some drawbacks to doing this, such as possible downslope corrosion of metal gutters and roof equipment, and the salt may leave a temporary whitish residue on the shingles once the melted ice has evaporated.

See CASMA Technical Bulletin No. 15 for more information.

Q: Can I use a shovel to remove snow and ice from my shingles?

A:  This activity is not recommended. Please see our article on ice dam removal.

See CASMA Technical Bulletin No. 15 for more information.

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