Manufacturers of Ice Dam Leak Prevention Products

• GAF Materials Corporation
  Weather Watch Ice & Water Barrier

• W. R. Grace & Co.
  "Ice and Water Shield"
• Johns Manville
• Bakor
  Eaveguard

08/2008

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Design Tips To Minimize Ice Dam Leakage and Damage

There is very little that you can do to prevent ice dams from forming. You can incorporate design features when building a new home or adding on that will minimize the size of ice dams. However, some of these features may not be visually appealing when used in remodeling situations, due to the fact that the overall design of the addition may not perfectly match your existing structure.

These type of situations are perfect examples of where one would make extensive use of the specialized roofing products that were mentioned earlier. Even in new construction, the use of ice dam roofing products is a great idea. They afford you peace of mind in the event of weather conditions that favor ice dam formation.

Design Suggestions

Avoid low slope roofs whenever possible. A low slope roof generally is considered one with a pitch of 5/12 or less. Low slope roofs make it easier for water to backup underneath the roofing materials.

Extend the roof overhang as much as possible from the outside wall of your home. If possible,give strong consideration to a 2 foot minimum overhang. In the event that an ice dam forms, this large overhang may keep the ice dam away from your exterior walls. In the event a leak does develop, in most cases, the leak will come through the soffit on the outside of your home, not your interior ceilings.

Avoid changes in roof pitch on the same plane. This simply means keeping the distance between the ridge of a roof and the gutter a straight line. Don't put a 'kink' in the roof. Snow and ice collect at these points. Usually, the lower roof plane in the 'kink' is also a low slope roof as we discussed above. Avoid these if at all possible.

Consider a raised heel height at the intersection point between the roof framing and the outside bearing walls. Heel height is a common term used by rough framing carpenters. It refers to the vertical distance between the top plate of the exterior wall and the top edge of the roof rafters as they pass over the outer edge of the wall plate.

Low heel heights (4 - 6") create a tremendous problem that aids in the formation of ice dams. Not only that, these low heel heights also contribute to the leakage of water into your house once an ice dam has formed.

Good building practices dictate that you should have a 2 inch airspace between the bottom of your roof deck and any ceiling or attic insulation. If your builder or carpenter uses a low heel height, you may only have 2 to 4 inches of insulation above the ceiling where the roof passes over the outside walls of your house. This condition enables heat to escape. This heat in turn keeps the roof immediately above this location warm enough to keep the water above the ice dam from freezing.This is the water that subsequently leaks into your house. By raising the heel height of your rafters or trusses, you benefit by having more insulation at this very critical location.

Cold Roofs

In climates where snow accumulations can be excessive, consider building a 'cold roof'. This is basically a roof on top of a roof. The upper roof is separated from the lower roof by a generous ventilating space. Outside air can flow freely between the two roofs. This keeps the upper roof, the one with the snow and ice on it, cold. Believe it or not, this is exactly what you want. You want the melt water to freeze as quickly as possible in ice dam situations. This keeps the water from backing up underneath the roofing materials. Also, a cold roof design virtually eliminates the problem we just discussed concerning low heel heights.

In the United States, Canada and the Northern Hemisphere for that matter, try to orient your house with a minimum of roof area having a northern exposure. Roofs with a northern exposure, generally, have more problems, because the snow and ice melt from these at a slower rate. During the winter months, the sun is at a lower position in the sky and these roofs often do not get direct sunlight. The sun is beneficial, because it will allow the snow and ice to melt more quickly. Roof decks, gutters and downspouts in direct sunlight often will have surface temperatures above freezing, while the air temperature will be below freezing. Avoid shaded roofs for the same reason.

Continuous Ventilation

If building new or remodeling, give serious consideration to installing excellent continuous ventilation. This consists of full soffit or eave ventilation used in conjunction with continuous ventilation at the top of your roof.

This type of ventilation permits a constant supply of cold air to flow beneath the surface of your roof. Once again, this is a favorable condition, as it keeps the roof surface cold and can actually cause the entire surface of the roof to freeze. This in turn permits any melt water to run on top of this ice shield on its way to the ground.

Continuous ventilation also has numerous other benefits. It helps to prevent attic condensation in the winter months. In the summer it helps to lower attic temperatures.

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The brown bent aluminum is step flashing. The aluminum extends under the shingle and goes up the roof under the next flashing about 2 to 3 inches. The roofer made a SERIOUS ERROR where my finger is pointing. There should be an additional piece of flashing that's called a kick-out flashing. The lower end is bent and soldered and directs the water out to the front face of the exterior siding or stucco. Copyright 2018 Tim Carter

"Flashings are things that stop leaks around things that pop up through your roof."

Roof Flashing Repair - Most Roof Leaks are at Flashings

The sources of a wide majority of residential roof leaks are roof flashings. For the most part, the correct installation of flashing material is what determines whether or not your roof will leak. The reason for this is quite simple.

What's the Best Way to Repair Roof Flashings?

I feel the best way to attempt roof flashing repair is to acquire full knowledge of what they are, what the best materials are, and how they're part of the entire roof system.

The last thing you should do is grab a can of black goo roofing cement or a few tubes of caulk thinking that's the way to repair a flashing. That's treating the symptom, not CURING the disease.

The vast majority of roofing products are quite easy to install. The manufacturers have engineered these products to be practically leak proof when they're installed on a simple roof.

However, there are very few simple roofs.

What is a Simple Roof?

A simple roof is one that doesn't have anything popping up through it. Examples of simple roofs are:

• dog houses
• small outdoor sheds
• firewood storage rack

Rarely will you find a plumbing vent stack, chimney, fan vent, pot vent, valley, a side wall projecting above the roof, etc. on a dog house.

You will, on the contrary, almost always find one of these items projecting through a residential house roof. The most common thing is a plumbing vent pipe. Watch this video to see how to make it leakproof for decades:

How Old is Roof Flashing Technology?

The engineering concerning flashings has been known for hundreds and hundreds of years. It is, in fact, very simple engineering. The system depends almost entirely on gravity. Gravity works with the flashing material and sheds the water onto the regular roofing materials.

If you use a flashing material that depends on some other method to shed water you can quite possibly develop a leak. Caulks, roofing cement, pitch, and similar materials depend on their stickiness or adhesive qualities to seal out water. These qualities can easily break down under constant exposure to the elements. If you want a leak-proof roof, stay away from these type of compounds.

Free & Fast Bids

CLICK HERE to get FREE & FAST BIDS from local roofing companies that will examine and replace your flashing.

What Are Flashings?

Flashings are things that stop leaks around things that pop up through your roof. Here's a list of common things that pop up through a roof:

• chimneys
• plumbing vent pipes
• dormers
• bath vent fans
• roof vents

How Long Should Flashings Last?

Roof flashings should last longer than the original roofing material.

Many people expect roofs to perform for a minimum of 15 to 20 years. Some roofs can be expected to last 50 to 80 years. This means that the materials which are used for flashings must have the same, or greater, lifespan as the roofing material itself.

What are the Best Flashing Materials?

The best flashing materials must also be able to be shaped easily and have the capability to be easily soldered, brazed or welded. This second point is crucial.

Copper, tin coated steel, lead, and galvanized steel are examples of fantastic traditional flashing materials.

Why Do Flashings Have to be Soldered?

The reason the flashing materials must have the capability of being soldered or brazed is quite simple. The soldering or brazing process of metal is similar to welding. These processes take two separate pieces of metal and make it one.

There are many, many times in flashing work where one has to bend around corners or splice two pieces of metal together.

These instances create seams which must be soldered or brazed. As I mentioned earlier, the flashing material must have a projected lifespan equal to or greater than that of the roofing material. Soldering or brazing metals together passes this test.

Do Flashings Have to Expand and Contract?

Flashing systems must also pass another test. They must be able to handle the constant expansion and contraction between roofing products and those things which are not roofing products. This battle of expansion and contraction can take place on a daily or seasonal basis.

The sun can create extremely hot surface temperatures during daylight hours, causing roofing materials to expand. At night, the temperature drops and the materials contract.

Do Flashings Move Because of Lumber Shrinkage?

Seasonal changes can cause the framing lumber to shrink and swell depending upon humidity and wood moisture content.

This shrinking and swelling cause the roof sheathing and rafters to move. The flashing materials must be able to withstand this movement and continue to be leak-proof. Well-engineered and installed two-part metal flashing systems can handle this movement with no problem.

On new construction, the framing lumber can shrink dramatically in the first year after construction. If one-part flashing systems are used, leaks can easily develop from the gaps that develop from the shrinking lumber.

Two-part flashing systems consist of a base or step flashing which is usually in contact or laced into the primary roofing material, and these are then covered by a counter flashing. The counter flashing is a separate piece of metal or building material which laps over the base or step flashing.

Should Counter Flashing Be Attached to the Flashings it Covers?

Counter flashing should not be attached (mechanically or soldered) to the base or step flashing. The two materials must be able to move independently of one another. The counter flashing can be made of a wide variety of materials. It can be wood siding, stucco, vinyl or aluminum siding, or other material which forms the outside surface of a wall.

In chimneys and along brick walls, the counter flashing is almost always the same metal which is used for the base or step flashing.

CLICK HERE to get FREE & FAST BIDS from local roofing companies that will examine and replace your flashing.

Does UV Light Hurt Metal Flashings?

Two-part metal flashing systems are not harmed in any way by the sun's ultra-violet (UV) rays. UV rays can easily defeat caulking, plastic roof cement or most other flashing substitutes. UV radiation can remove the elasticity of these products and make them brittle.

When they become brittle, they can no longer handle the daily expansion and contraction. Also, very few of these products have a lifespan equal to or greater than roofing products. They are temporary remedies at best. Only consider using them for emergency type repairs.

Should You Paint Roof Flashings?

Flashing materials that can rust (tin coated steel or galvanized steel) should always be painted. They often are not painted correctly by roofers. These metals must have special primers applied first and then the proper number of finish coats of paint.

Also, it's extremely important to wash these metals with soap and water or paint thinner before painting!!! These metals have a very light coating of oil which is applied during the milling process. If the oil is not removed, the paint job will fail. You will be battling peeling paint long into the future.

Is Aluminum a Good Flashing Material?

Aluminum is not a bad flashing material if you watch where you use it. Two big downsides to aluminum are:

• it can't be soldered with ease
• it corrodes if it touches brick or stone mortar

Avoid using aluminum flashing material. Aluminum cannot be soldered. Also, if it is used in flashing chimneys or brick walls, it will rapidly corrode. The chemical makeup of the mortar attacks and eats the aluminum! Do not allow your roofer to use aluminum!!!

Are Flashings the Most Complex Part of a Roof?

Yes, flashings are, for the most part, the most technical aspect of roofing. Their installation requires an experienced individual in almost all cases. Soldering vertical surfaces requires skill and knowledge. Professional roofers possess these talents. Professionals realize the importance of flashings. They know that flashings are the weak link in the chain. You should realize this also.

The art of installing flashings cannot be described in this short bulletin. In fact, many books do not fully cover the subject. You have to research several books to get the full picture. I have developed a partial list of some publications which do a good job of illustrating and explaining roof flashings.

Many of these are available at libraries or larger bookstores. I highly recommend that you consult several publications to get a full understanding of the complexity of roof flashings. The more you realize how complicated flashings are, the better your chances of hiring the best professional. Good luck!

CLICK HERE to get FREE & FAST BIDS from local roofing companies that will examine and replace your flashing.

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Excellent Illustrated Publications

Quick Guide: Roofing. Dave Schiff, Creative Homeowner, 2nd ed., 1995.

Roofing: Step-by-Step Projects Creative Homeowner Press, 2004. "Everything homeowner's need to install a roof properly. Provides detailed instructions for jobs such as flashing and fixing leaks..."

Roofing Materials & Installation  William P. Spence, Sterling Publishing Co., 2004.  "Learn how to make repairs, prepare the roof for the construction process, and choose the best materials for your home."

Roofing: The Best of Fine Homebuilding. Taunton Press, 1996.

All About Roofing and Siding Basics. Ortho Books, 2001.

The Roofing Handbook. Robert Scharff, McGraw-Hill, 2nd ed., 2000. "The most complete A-to-Z handbook on the basics of residential roofing, with over 250 illustrations."

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Asphalt shingles are by far the most prolific roofing material used in residential construction today. Virtually 80 percent of all residential roofing materials are manufactured by asphalt roofing product companies. The industry has come a long way since its beginning in 1893. Today's asphalt shingle products are far superior to products made just 25 years ago.

Operator Error

The construction industry (of which I was a participant for 20 years) has a major flaw. The learning process in virtually every field is either visual or verbal. Young people beginning to work in the industry simply learn by doing what they are told or by watching more experienced individuals. There is very little reading that takes place. The only widespread exposure of written learning material that I am aware of is the textbook material available to vocational students or those few who go through apprenticeship programs (plumbers, electricians, some HVAC).

Relying on verbal or visual information is simply not acceptable in today's world. Professionals in fields other than building and remodeling are formally educated and continue to read on a regular basis about changes in their profession.

A construction worker who is just entering the field may be taught by an individual who has been doing something wrong or against manufacturer's recommendations for years. In many instances, these individuals do not even realize that they are making mistakes.

Many individuals who install asphalt roofing shingles do not follow written, established roofing practices as outlined by manufacturers and roofing associations. This is prevalent in the industry. In fact, in my own hometown, I am aware of only one roofing contractor who correctly installs asphalt shingles! That means that 98 to 99 percent of all the asphalt roofs installed in Cincinnati are susceptible to leaks or premature failure. The same thing quite possibly is happening in your city or town.

The Basics

The performance of asphalt roofing shingles is dependent upon several factors. A mistake in any one area can cause failure of the system which manifests itself to you as a leak. Some of these factors are roof slope, ventilation, roof deck to which shingles are applied, drip edges, flashings, fasteners (nails or staples), application of fasteners, quantity of fasteners, placement of fasteners and condition of asphalt shingles prior to application.

Roof Slope

Asphalt roofing shingles cannot be successfully installed on each and every roof. These products depend heavily on gravity to keep water from entering your house. As the slope or pitch of a roof increases (gets steeper), gravity can pull the water off of your roof faster. Thus, the steeper your roof, generally, the better asphalt shingles perform.

Roof slope is commonly called out as the amount of vertical rise per amount of horizontal run. By convention, the amount of horizontal run is commonly called out as 12 inches. A common roof slope (pitch) used in many ranch houses is 4 inches of vertical rise for every 12 inches of horizontal run. This is called out as a 4/12 pitch roof.

Asphalt shingles can be applied on roofs with a slope (pitch) as low as 4/12 and as high as 21/12 using standard installation practices. Low slope roofs between 2/12 and 4/12 require special application methods, as do roofs that exceed 21/12 pitch.

Ventilation

Poor attic ventilation can adversely affect shingle life. Prolonged exposure to high temperatures can accelerate the aging process of asphalt shingles. Excessive moisture buildup in attic spaces can cause water vapor to penetrate asphalt shingles. This water vapor in turn is boiled by the sun and causes blisters in shingles. Excessive attic moisture can also cause the roof framing and decking members to swell. Excessive swelling can buckle shingles, which in turn can fracture them. Leaks may develop as a result of fractures. Proper ventilation of attic spaces will remove excess heat and moisture. The minimum ventilation requirements are a net free ventilation area of 1 square foot for every 150 square feet of ceiling area. Net free area refers to the unobstructed area of ventilation systems. Remember that insect screening restricts air flow! You can't simply use the area of the holes you cut in your roof to determine the free net area. Virtually every well made ventilation cover or system tells you the net free area of the vent or per linear foot of ridge vent.

Roof Deck

The roof deck or surface to which the shingles are going to be applied must be solid and rigid. It has to be able to support with minimal deflection the weight of the roofing materials, snow loads and anyone who is walking on the roof. The decking must also be installed properly. Plywood installed improperly can and will buckle. I addressed this subject in this plywood article.

Drip Edges

Water can easily penetrate roofs at the bottom and side edges of roofs. This is especially true when rain is accompanied by wind. Drip edges are corrosion resistant metal which protects the wood roof decking from this water. They usually project a minimum of 3 inches onto the deck. The metal at the edge of the roof decking is then bent down a minimum of 1 inch onto the rake trim and gutter boards.

Flashings

My guess is that over 90 percent of roof leaks are flashing-related failures. Flashings are the transition materials used to blend roofing materials into things that are not roofing materials (chimneys, sidewalls, skylights, plumbing vent pipes, etc.) The installation of flashings and the use of proper flashing materials is vitally important. For example, I have seen countless chimney flashing failures due to the use of aluminum. A roofer, thinking that he is providing a maintenance free flashing, installs aluminum flashing around a masonry chimney. Little does he (she) know, aluminum is rapidly corroded by the alkalies in the mortar between the bricks! After several years, the aluminum simply dissolves. Also, aluminum cannot be soldered. Chimney flashings almost always require soldering at the corners of the base and head flashings! The only ones that do not are pre-engineered chimney flashings, and these are rare.

Flashings require skill to fabricate and install. Step flashings, for example, need to be specific sizes and need to be laced and overlapped into each layer of roofing. They need to be bent just right so as not to hold up a shingle. Step flashings are an integral part of a two component flashing system. They require a separate free-floating counter flashing. I addressed flashings in this related article. Do not underestimate the importance or necessity of proper installation of metal roof flashings. Trust me, those difficult and troublesome leaks are probably being caused by a flashing.

Fasteners

Fasteners are the nails and staples used to apply asphalt shingles to a roof deck surface. Virtually every manufacturer of asphalt roofing approves the use of staples. However, the Asphalt Roofing Manufacturers Association recommends that roofing nails are the preferred fastening system for asphalt shingles.

Believe it or not, you just can't use any nail or staple to install asphalt shingles. Nails and staples need to be corrosion-resistant. Moisture does collect beneath shingles, both in liquid and vapor form. This moisture will rust non-protected iron nails.

The shank diameter of nails must be a minimum of 0.105 inch (12 gauge) and the head of the nail must not be less than 3/8 inch. Staples must have a minimum outside crown (width) of 15/16inch. They should be made from wire that is a minimum of 0.0625 inch (16 gauge).

Fasteners must be of a sufficient length to completely penetrate at least 3/4 inch into the roof deck. If the roof decking material is less than 3/4 inch thick, the nail must penetrate the decking completely and extend a minimum of 1/8 inch past the inner surface of the roof decking.

Fasteners must be placed correctly. They should be driven so that the bottom of the nail head or staple crown is flush with the shingle. Fasteners driven too deep, crooked or not far enough are simply not acceptable.

Quantity & Placement of Fasteners

There are many different shingle types available today. The standard 3 tab shingle is common to many homeowners, however dimensional type asphalt shingles are becoming ever more popular. Most of these shingles are designed to expose 5 inches of the shingle to the weather. In cases such as these, the manufacturers usually require that you place the fasteners in specific locations along a line 5 5/8 inches from the bottom (exposed) edge of the shingle.

In all shingles that have a thermoplastic asphalt self sealing compound, the nails are to be placed below this strip!

Virtually, every manufacturer requires a minimum of four per to determine the proper location of the fasteners.

The location of the fasteners is critical for a very simple reason. As each successive course of shingle is applied, it is offset from the course below. This offset is needed to adequately cover the butt joint of the course below. This butt joint is where water leaks into your house. Fastener locations are designed so that they receive the maximum protection from the course of shingles immediately above them. Any deviation from the nailing pattern increases your chances of a leak!

High Wind Area Nailing Pattern

Asphalt shingles applied in areas subject to high winds need two extra fasteners (total of six) per shingle. These two extra fasteners are attached along the same line as the original four. The two fasteners within the body of the shingle are moved slightly to the left and/or the right and an extra fastener is applied so that it is 2 inches away. Once again, the locations are specific to each type of shingle and you (or your roofer) need to read the shingle wrapper to determine the correct location.

Condition of Materials

Asphalt shingles can absorb water. Waterlogged shingles cannot be successfully applied to a roof and achieve maximum performance. Thus, it is imperative that they be stored in such a way as to remain dry prior to application. They should always be stored on a flat surface. Buckled shingles should never be applied. Modern asphalt shingles also become very brittle at temperatures below 40 degrees F. Care must be taken so as not to fracture them if applying them in cold weather conditions.

Reroofing over existing roofs

There are many considerations which must be studied before applying new asphalt shingles over an existing roofing material. Weight, fastener holding capability, smoothness of existing roof, local code requirements, etc. must be investigated. Do not assume that you can simply apply a new layer of asphalt shingles over an existing roof. Remember that asphalt is a plastic material. When the shingles get hot, they will conform to the surface upon which they lie.

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Asphalt Shingle Manufacturers

• Atlas Roofing Corp.

• Certainteed Corporation

• Elk Corporation

• GAF Materials Corporation

• Owens-Corning

• Tamko Roofing Products, Inc.

• IKO

Roofing Associations

Check out the following web sites. The Asphalt Roofing Manufacturers Association has an excellent publication called Residential Asphalt Roofing Manual. It is the best book I have seen which clearly explains what you need to know about having your roof installed properly. Various manufacturers, such as Certainteed, also have excellent installation literature. Read as much as you can, and good luck on your next project!

• Asphalt Roofing Manufacturers Assoc.

• National Roofing Foundation

• Roofing Industry Education Institute

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To Felt or not to Felt, That is the Question!

One of the most common mistakes being made today in the installation of asphalt shingles on new or reroofing work is the practice of not using felt underlayment. Many, many thousands of new homes do not have felt beneath the shingles. This is a HUGE mistake!

Many asphalt shingles that are installed on residential roofs carry a Class A fire rating. This rating is given to the shingles by independent laboratories. The ratings are granted only when the shingles are installed as they were tested in laboratory conditions. The shingles are tested with felt in place under the shingles. As such, if felt is deleted on your job, the shingles have no fire rating. This may not seem to you to be a big deal, however, it may be a very big deal to your insurance company. It may be in your policy that they won't pay a claim if the shingles are not installed or maintained according to manufacturer's specifications, etc. I surely would check into this if I were you.

Remember, shingles rely on gravity to keep water from entering your house. It is very possible for wind driven rain to get underneath your shingles or to enter along valleys (especially when the valley shingles have been improperly trimmed!) Without felt, you have no hope of stopping a leak. With felt, there is a possibility that the water will travel down the felt and not enter your house.

Felt also helps to bridge irregularities in roof decking. It can make your shingle job look better.

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Cedar shakes are one of the ultimate roofing materials. Perhaps this is why asphalt manufacturers have tried to mimic cedar shakes for quite some time. The color, texture and overall appearance of a cedar shake roof is hard to duplicate. However, as you might expect, this beauty comes with a price tag. Cedar shake roofs require periodic maintenance in order to retain their positive qualities.

Wood, left unprotected, can be easily abused by sunlight and water. Some wood though, contains naturally occurring chemicals that withstand, to a degree, the effects of water. Sunlight, especially ultraviolet (UV) light, readily attacks any unprotected wood.

Sunlight = Trouble

Sunlight, far and away, is the biggest enemy of cedar shake roofs. The UV rays of the sun actually break down lignin (a component of wood cells.) This breakdown occurs on a small scale and, as such, is invisible to the naked eye. This reaction only happens at the top surface of the cedar shake. However, wind and rain wash away the broken-down wood cells and expose a new layer. So the process is ongoing. The color change you see when cedar shakes (or any wood for that matter) turn gray is a testimonial to this physical breakdown of the wood.

UV light also causes another problem. In the process of destroying the lignin, very small cracks develop in the cedar shakes. These cracks allow water, bacteria, dirt, etc. to drive deeper into the wood. This, as you will see in a few moments, accelerates the destruction process.

Natural Preservatives

Cedar is one of the naturally occurring woods that contain high amounts of natural preservatives. The old growth cedar logs cut down 100 years ago tended to have higher amounts of these natural chemicals than the cedar logs of today. This is one reason why cedar roofs at the turn of the century required little or no maintenance.

The problem with these natural preservatives is that they dissolve in water. In fact, these chemicals are often referred to as extractives, because they can be "extracted" from the wood by water and other solvents.

When these extractives are leached from the cedar shakes, another phase of destruction begins. Water can more easily enter the wood cells, causing shrinking and swelling. Fungi which like to inhabit wood can also more easily grab a foothold. These fungi start a destructive process which, when left unchecked, will cause premature roof failure in short order.

Water Tubes

The nature of sawn wood causes it to more easily degrade than an unsawn log or branch. When a tree is living, it really is a collection of tubes, very small ones indeed, that extend from the ground up to the top of each branch.

However, when you saw a tree into logs and then turn it into something like cedar shakes, you partially expose, along their entire length, some of these tubes. Under a microscope these exposed tubes look something like U-shaped valleys or a freshly furrowed field. The depressions are great places for water, dirt, bacteria, mold spores, etc. to get trapped. Other roofing materials such as asphalt shingles, metal, slate, tile, etc. don't have this problem.

Sealants and preservatives can go a long way in temporarily filling these exposed tubes. In this way, you slow down water penetration which in turn slows down the loss of the natural extractive chemicals.

Keeping your Roof Dry

The key to extended life for cedar shakes is keeping them dry. Remember, water dissolves the extractive chemicals. Knowing this, do whatever is possible to remove debris such as leaves, pine needles, twigs, moss, low hanging branches, etc. from your roof. These things tend to hold moisture and slow down the evaporation of water from your shakes.

If building new, consider using as steep a pitch as possible. Low pitched roofs wear out faster than steep pitched roofs, it's that simple.

Periodically check your roof for debris buildup. This simple investment of time will pay big dividends. Your cedar shake roof could quite possibly last a lifetime with just a little care.

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Periodic Cleaning

As mentioned in another article, you must keep your roof clean and free of debris. Cedar roofs need vast amounts of air to keep them dry. Trim overhanging tree branches so that there is at least a 3 to 4 foot area above the roof. Don't let overhanging branches rub the roof or hang too closely. They simply inhibit evaporation of rain water or morning dew.

Moss Control

Moss is a major problem on shaded cedar shake roofs. Its presence can significantly shorten the life of your roof. Copper and zinc have proven to be very effective at stopping the growth of moss on cedar roofs. A copper ridge flashing may be all it takes to keep your roof clear of moss. You can also install zinc strips which expose 2 inches of metal at certain intervals as well. These strips release molecules of zinc with each rainfall. The strips look a little funny when first installed, however, they weather and take on a dull appearance in short order. They are a tremendous investment. Don't underestimate their value.

Cleaning a Dirty Roof

There are several ways to clean a cedar roof. Power washing with a pressurized machine is very effective. However, if an untrained person performs this procedure, shake damage, leakage, wood erosion, etc. are REAL possibilities.

When using water on a roof, either from a hose or a power washer, NEVER spray up the roof. Roofs use gravity to keep your house dry. Spraying water up the roof is not natural. By doing this, you will drive water up under your shakes. Drive water far enough and it will leak into your house. I guarantee it!

Many past publications have promoted the use of a cleaning solution that contains either regular or commercial strength bleach (sodium or calcium hypochlorite). These forms of bleach can actually harm your cedar shakes. They can cause cellular damage similar to that caused by UV light. They also will remove (bleach out) the natural extractive chemicals which give cedar its beautiful color tones. A better solution is to use oxygen bleach. It will clean your cedar shakes with no problems. It will not remove the color and it is environmentally safe, unlike standard bleaches.

Sealing & Preserving

After cleaning your roof, let it dry. This may take 2 to 3 days. Then, apply whichever product you have chosen exactly as it says to doon the label. Do not become your own testing laboratory. Manufacturers have gone to great lengths to determine application techniques and quantities. If you deviate from their instructions, you only stand to hurt yourself.

Using the proper type of application equipment is essential. If a product says to use a power airless sprayer, don't try to substitute a pump garden type sprayer. Use common sense!

Roof Safety

Roofs are dangerous places. I have fallen off several and lived to tell about it. Moss covered cedar shake roofs are like tilted, elevated ice skating rinks. Need I say more? Add water to these roofs and they become practically impassable.

Cleaning and sealing cedar shake roofs should not be attempted by a novice homeowner. Serious injury and death are very real possibilities.

Give serious consideration to hiring this job out. Let a seasoned professional clean and seal your cedar roof. Be absolutely sure this individual has worked on such jobs and is insured with Worker's Compensation. Make sure they attach a copy of their current certificate, indicating paid up coverage, to your contract. Don't underestimate how dangerous this job can be.

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Cedar Shakes - Literature / Association / Preservatives

NOTE FROM TIM CARTER - Founder of AsktheBuilder.com - posted October, 2016: I no longer would apply Defy deck sealer to any exterior wood that I own at my own home. Defy is made by the Saver Systems company listed below.

Want more information about cedar shakes? Everything you ever wanted to know is readily available and free for the asking. You can learn about how shakes are made, graded, treated for fire resistance, cleaning, repair, installation on new roofs, etc. Simply go to the following web site:

There are over 250 cedar producing mills in America and Canada. They produce different levels of quality. You need to make sure you have the best shakes if installing new or rebuilding an existing roof. If you want the best, you need to specify Certigrade, Certi-Split, or Certi-Sawn shakes or shingles. These trademark names can only be used by mills which are members of the Cedar Shake Bureau.

If you want to get up to speed quickly with respect to cedar shakes and shingles, read the Guide to Cedar Roofing on the website of Watkins Sawmills (www.watkinsawmills.com). This booklet hits the high spots and tells you important information concerning cedar shakes.

Preservatives & Sealants for Cedar Shake Roofs

• Sikkens Cetol SRD
• Duckback Products, Inc.
• Flood Company
• Saver Systems
• Wolman Company

Check out the product literature of these companies. Be sure to confirm that the product you choose can be used on your cedar shakes. Follow directions to the letter when using any of the products.

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