Posts Tagged ‘Roofing’

What Are My Roofing Options?

February 15, 2011

Roofing Guide

Asphalt shingles—used on an overwhelming share of the U.S. residential roofs—can be reinforced with fiberglass materials. Fiberglass-reinforced products are more durable and dominate the market.

Fiberglass shingles have a fiberglass mat, top-and-bottom layers of asphalt and mineral granules. They are available in architectural grades and a variety of colors that offer a textured appearance.

Wood shingles and shakes are typically made from cedar, redwood, and southern pine. Shingles are machine-sawn; shakes are hand-hewn and rougher looking. Their natural look is popular but brush fire concerns limit their use.

Slate is quarried and applied mostly in the northeast and comes in different colors and grades. Considered virtually indestructible, it is, however, more expensive than other roofing materials.

Synthetic roof products simulate various types of traditional roof coverings, such as slate and wood shingles and shakes. A point to consider: Although synthetic roof products may simulate the appearance of traditional roof coverings, they do not necessarily have the same properties.

All roof systems have five basic components:

Structure: the rafters and trusses that support the sheathing.

Deck/sheathing: the boards or sheet material that are fastened to the roof rafters to cover a house.

Underlayment: a sheet of asphalt-saturated material used as a secondary layer of protection for the roof deck.

Roof covering: shingles, tiles, etc., that protect the sheathing from weather.

Drainage: the features of the roof system’s design, such as shape, slope, layout, etc., that affect its ability to shed water.

Flashing: sheet metal or other material laid into the various joints and valleys of a roof system to prevent water seepage.

Ventilation is Key

One of the most critical factors in roof system durability is proper ventilation. Without it, heat and moisture buildup in the attic area combine to cause rafters and sheathing to rot, roof shingles to buckle, and insulation to lose its effectiveness.

It is important never to block sources of roof ventilation, such as louvers, ridge vents, or soffit vents. Proper attic ventilation will help prevent structural damage, increase the life of the roofing material and reduce energy consumption.

In addition to the free flow of air, insulation plays a key role in proper attic ventilation. An ideal attic has:

  • A gap-free layer of insulation to protect again heat gain or loss
  • A vapor retarder under the insulation to stop moisture from rising into the attic
  • Enough vented spaces properly allow air to pass in and out freely
  • A minimum of 1 inch between the insulation and roof sheathing

Roof Enemies

Sun: Heat and ultraviolet rays cause roofing materials to deteriorate over time.

Rain: When underneath roofing, water can work its way to the deck and begin to cause rot.

Wind: High winds can lift the roof edges and force water underneath.

Condensation: The buildup of relatively warm, moisture-laden air in a poorly ventilated attic promotes decay of the wood sheathing and rafters.

Moss and algae: Moss can grow on wood shingles and shakes if they are kept moist by poor sunlight conditions or bad drainage. Once it grows, moss holds even more moisture to the roof surface, causing rot, and its roots actually work their way into the wood.

Algae also grows in damp, shaded areas on wood or asphalt shingle roof systems. Besides creating an ugly black-green stain, algae can retain moisture, causing rot and deterioration.

Trees and bushes should be trimmed away from the house to eliminate damp, shaded areas, and gutters should be kept clean to ensure good drainage. Tree branches touching the roof will scratch and gouge roofing materials as they are blown back and forth. Leaves retain moisture and cause rot.

Missing or torn shingles: No longer complete protection.

Shingle deterioration: When shingles get old and worn out, they curl, split, and lose their waterproofing effectiveness and are more easily blown off, torn, or lifted by wind gusts.

Flashing deterioration: Many apparent roof leaks really are flashing leaks around chimneys, vents, skylights, and wall/roof junctions.

How long can you expect a roof system to last?

The condition and lifespan of your roof system will depend on the type of roof system you have, the effects of the local environment. According to the American Society of Home Inspectors, asphalt shingles generally last 15 to 20 years; wood shingle/shakes, 10 to 40 years; clay/concrete tiles, 20+ years; slate, 30 to 100 years; and metal roofing, 15 to 40+ years. Most top-of-the-line roofing product manufacturers offer a variety of warranties.

When selecting a new roof, cost and durability are tops, but aesthetics and architectural style are important, too. The right roof balances these four considerations.

To discuss all of your options, contact a Minnesota roofing contractor today!

Advertisements

Ice Dams Still Causing Problems For Minnesota Homeowners

January 27, 2011

Ice Dam Removal | Steam Removal of Ice Dams

Ice damming is a big problem here in Minnesota this year. Record snowfall amounts in December, preceded and interspersed by bouts of sleety precipitation, produced the perfect storm for ice dams to flourish.

“There’s a lot of leaks out there,” say Minnesota roofing contractors, who have been taking calls for help. After a series of wimpy winters, this one and last year’s have prompted ice dams to return with a vengeance. As a result, Minnesota homes are being affected much earlier than usual this year.

Ice dams form when snow accumulates on a roof that’s too warm, then melts and drains down to refreeze at the colder overhangs of eaves. The water that collects behind the frozen dams may seep through the roof and down into a structure. Poorly insulated and inadequately vented attics are the biggest contributors to ice buildups, which can be mitigated by clearing snow from roofs.

Long-handled roof rakes can be employed to pull off the first few feet of snow behind eaves, but locally they’ve become a scarcity. Menards ran out over the weekend, and Home Depot’s supply was depleted for the third time this winter.

Complete removal of roof snow is best, and is best if the work is done by a contractor using a steam unit to clear heavy snow and ice buildups. This method melts the ice dam in a manner that will not damage your roof.

Ice shield membranes, routinely installed along roof edges before new shingles are installed, make a big preventative difference when it comes to water issues produced by ice dam formations.

Prior to five or six years ago building codes called for membranes to extend three feet up from an exterior wall. Under the new code, 6-foot rows of membranes are now standard, and some homeowners request even more. Some people have wanted a membrane on the entire roof.

Contractors say that an ounce-of-prevention is worth-a-pound-of-cure. Thousands of homeowners in the community who had new roofs installed following severe summer storms may have been lulled into a false sense of security. Ice shield membranes guard against water penetration but can’t prevent ice dams that, if left untended, can extend upward beyond the shields.

According to the University of Minnesota Extension Service, problems occur when a series of conditions coincide:

A roof’s upper surface must average above 32 degrees for sustained periods while the lower surfaces average below freezing temperatures. The dams form in the areas that are below freezing, and water collects behind them in areas that are not.

In addition to removing roof snow, ice dam prevention involves controlling heat loss from the house to the attic. This can be achieved by enhancing ceiling insulation that keeps heat out of the attic, thereby preventing the roof from heating up, and by keeping roof vents free of snow.

And as a related precaution, snow should be cleared away from outside gas meters to guard against blockage of regulator vents that could cause gas leaks inside the home.

If you are one of the many Minnesota homeowners with roof damage from ice dams, contact a Minnesota roofing contractor today!

GAF-Elk Shingles Now Pass Two Toughest ASTM Wind Tests For Superior Protection

January 10, 2011

GAF-Elk Shingles Now Pass Two Toughest ASTM Wind Test

GAF Materials Corporation, North America’s largest roofing manufacturer, today confirms that every shingle it manufactures now passes the two toughest wind tests in the roofing industry: ASTM D3161 Class F 110 mph and ASTM D7158 Class H 150 mph. Roofing contractors in the U.S. can now install any GAF-Elk shingle in any area without concern about whether they comply with national or local wind speed requirements. To its knowledge, GAF may be the only shingle manufacturer that can make this claim.

In order to pass these arduous ASTM tests, the shingles were first subjected to 110 mph winds using ASTM’s testing protocol. Not only did the GAF-Elk shingles pass, but they exceeded the test requirements by enduring the test conditions for a full two hours, showing no damage. They were then tested using the 150 mph wind test protocol, and passed again, thanks to GAF-Elk’s DuraGrip® adhesive’s tight seal.

In case some contractors think that wind may not be a major concern outside of obvious coastal areas, according to the American Society of Civil Engineers (who develop wind guidelines for construction in the U.S.), the lowest wind speed that home designers should plan for is 85 miles per hour. In fact, for about 110 million people in the United States from Maine to Texas, codes require 110 mph or greater ASTM classifications. Further, high winds are not just a concern for coastal regions, as local geography can cause high winds at peaks, mountain passes, or large water bodies.

The threat is real. According to The Institute for Business and Home Safety, more than 60% of all homes in the U.S. are vulnerable to damage from high winds generated by storms and heavy rains. Blown-off shingles can leave a home vulnerable to water damage, mildew, and mold and damaged roofs are expensive to repair. As part of its continuing effort to provide the highest quality shingles to homeowners, GAF-Elk submitted to ASTM’s severe testing regimen and successfully proved the quality and reliability of its shingles for use in any market in the U.S.

Because of GAF-Elk’s stringent standards, only the top 3% of all roofing contractors have qualified as Master Elite contractors! Choosing a GAF-Elk Master Elite contractor is your assurance that you’ll be dealing with a quality, reputable, and dependable professional contractor — not some “fly-by-nighter.”

Source: http://www.gaf.com

St. Paul Advises Residents To Clear Roofs

December 31, 2010

St. Paul Advises Residents To Clear Roofs

The city of St. Paul is advising residents to take action to clear their rooftops of ice and snow now, to avoid potential damage in the future. Taking action now can also help you avoid costly repairs to your roof  from ice dams.

Read full story:  CBS Minnesota – News, Sports, Weather, Traffic, and the Best of Minnesota

Short URL:
http://tld30.com/a/?xRISI

Avoiding Roofing Disasters

December 28, 2010

Avoid Common Mistakes That Could Cost You Thousands!

Exciting and informative, this video gives you the inside scoop on selecting a new roofing system, the right contractor, and best materials to protect your biggest asset – your home.

The result… your ultimate peace of mind!

Learn how to make not only the right choice, but the “safest” choice for your roofing needs. The following educational video is provided by GAF-ELK Roofing Manufacturing. United Roofing and Remodeling Inc. is able to bring you this video because of our Master Elite Certification from GAF-ELK.
The video features Jim Hartz (national TV news correspondent) and JoAnne Liebeler (from Hometime® seen on Public Television).

Because of GAF-Elk’s stringent standards, only the top 3% of all roofing contractors have qualified as Master Elite contractors! Choosing a GAF-Elk Master Elite contractor is your assurance that you’ll be dealing with a quality, reputable, and dependable professional contractor — not some “fly-by-night” contractor that is not available to answer your questions.

Source: www.gaf.com

Last Call For Homeowners To Take Advantage Energy Of Tax Credits

December 15, 2010

What Types Of Roofs Can Qualify For The ENERGY STAR Label?

The days are quickly running out for homeowners looking to upgrade the energy efficiency of their home this year.  Homeowners must have projects completed, products installed and ready to use, before the end of the month to qualify.

You can qualify for up to $1,500 in tax credits when filing 2010 income tax returns.  Home owner have until Dec. 31 to qualify for the tax credit.

Home owners can take advantage of the tax credit (Internal Revenue Code Section 25C) for efficiency upgrades made to existing homes, such as for certain types of insulation, windows, roofs, water heaters, heat pumps, furnaces and air conditioners.  Tax credits are available for 30 percent of the cost up to $1,500 for 2009 and 2010.

ENERGY STAR roof specifications are not restricted to any particular type of roof product, and include:

  • built-up-roofs
  • metal roofing products
  • roof tiles
  • spray polyurethane foam roof systems
  • asphalt shingles
  • single-ply membranes
  • roof coating products
  • modified bitumen

ENERGY STAR qualified roof products reflect more of the sun’s rays.  This can lower roof surface temperature  decreasing the amount of heat transferred into a building.  Roof products qualify for the ENERGY STAR label based on their solar reflectance, without compromising product quality and performance.

ENERGY STAR labeled roofs are more common on commercial buildings, but can also be used on residential homes.  Talk to a Minnesota roofing contractor to find out which roof system is the right choice for your home or building.

Prevent Those “Dam” Leaks!

December 13, 2010

Preventing Ice Dams

With the 16 plus inches of snow we were blessed with in Anoka County last weekend (and even more in Washington County to the south and east) it looks like we are in for a good old fashion Minnesota winter. Heading to grandmother’s house this holiday, will take us all over lots and lots of white and drifted snow.

The snow is pretty for photos and fun for snowmobilers, skiers, boarders and sledders but not so great for our houses. With accumulated snow well into the foot range already, there is another necessary chore to add to the list to avoid homeowner headaches that come with the snow melt. We have to remove the snow from our roofs!

Though a shingled roof won’t pop like the Metrodome did over the weekend , ceilings have been known to become waterlogged and collapse under the stress of too much snow and ice dams.

Although individual cases look different, and often result in different types of damage, all ice-dam situations have two things in common: They happen because melting snow pools behind dams of ice at the roof’s edge and leaks into the house; also, ice dams and the damage that results from them is avoidable.

Cause

Ice dams form when melted snow refreezes at roof edges. Anyone who has lived in cold climates has seen ice dams. We’ve enjoyed the sparkling beauty of ice formations built along roof eaves (of other people’s homes). However, most of us don’t stop to understand why these ice bands form until our homes are damaged by them.

Three things are required for an ice dam to form: snow, heat to melt the snow and cold to refreeze the melted snow into solid ice. Ice dams can form when as little as 1 or 2 inches of snow accumulates on a roof – if the snowfall is followed by several days of sub-freezing temperatures. Ice dams develop as snow on the upper part of the roof melts. Water runs down the roof slope under the blanket of snow and refreezes into a band of ice at the roof’s edge creating a “dam”. Additional snow-melt pools against the dam and eventually leaks into the building through the roof or roof trim.

The reason ice-dams form along the roof’s lower edge, usually above the overhang, is straight-forward. The upper roof surface (toward the ridgeline) is at a temperature that is above freezing. And the lower part of the roof surface (along the eaves) is below freezing. The upper roof surface is located directly above the living space. Heat lost from the house warms this section of the roof, melting snow in this area. During periods of sub-freezing temperature the lower regions of the roof deck remain at sub-freezing ambient temperatures. Roof overhangs are not warmed by indoor heat-loss.

Deeper snow and colder temperatures increase the likelihood and size of ice dams. Every inch of snow that accumulates on the roof’s surface insulates the roof deck a little more, trapping more indoor heat beneath the roof deck. Frigid outdoor temperatures assure a fast and deep freeze at the eaves. So the worst ice dams usually occur when a deep snow is followed by very cold weather.

Damage

It’s easy to understand that allowing water to leak into your house is a bad idea. Ice dams cause millions of dollars of damage every year. Much of the damage is apparent. Water-stained ceilings, dislodged roof shingles, sagging ice-filled gutters, peeling paint, and damaged plaster are all easily recognized and usually repaired when weather or budgets permit. But other damage is not as obvious and often goes unchecked.

Ice dams usually develop along roof eaves, above the plateline of exterior walls. Heat lost from homes at this point aggravates snow melting and ice-dam development. There are two reasons for increased heat loss at this point: Rafters on most homes sit directly on top of exterior walls leaving a shallow space for insulation between the top of the wall and underside of the roof sheathing: Low R-value = heat loss! And secondly, builders are not particularly fussy when it comes to air-sealing this point to prevent the movement of warm indoor air up to the underside of the roof surface. Air can leak through wire and plumbing penetrations here. Also warm indoor air can leak from the wall cavities rising upward and passing between the small cracks that exist between the wall top-plate and drywall.

Roof leaks wet attic insulation. In the short term, wet insulation doesn’t work well. Over the long term, water-soaked insulation is compressed so that even after it dries, the insulation in the ceiling is not as thick. Thinner insulation means lower R-values. It is a vicious cycle. The more heat lost – the more ice dams form – the more it leaks – the more the insulation gets damaged – and so on. As a result you pay more to heat (and cool) your house. Cellulose insulation is hygroscopic and particularly vulnerable to the hazards of wetting.

Water often leaks down within the wall frame where it wets wall insulation and causes it to sag leaving uninsulated voids at the top of the wall . Energy dollars are again robbed, but more importantly, moisture gets trapped within the wall cavity between the exterior plywood sheathing and interior vapor barrier. The result: smelly, rotting wall cavities. Structural framing members can decay. Metal fasteners may corrode. Mold and mildew can form on wall surfaces as a result of elevated humidity levels. Exterior and interior paint blisters and peels. And the well-being of allergy-sensitive individuals is compromised.

Peeling of wall paint deserves special attention here because its cause may be difficult to recognize. It is unlikely that wall paint (interior or exterior) will blister or peel when ice dams are visible. Paint peels long after the ice and all signs of a roof leak have evaporated.

Water from ice dams infiltrate wall cavities. It dampens building materials and raises the relative humidity within wall frames. The moisture within the wall cavity eventually wets interior wall coverings and exterior claddings as it tries to escape (as either liquid or vapor). As a result, interior and exterior walls shed its skin of paint.

So the message here is to check your home carefully when ice dams form. Investigate even when there doesn’t appear to be a leak. Look at the underside of the roof sheathing and roof trim to make sure they haven’t gotten wet. Check the insulation for dampness. And when leaks inside your home develop, be prepared. Water penetration often follows pathways difficult follow. Don’t just patch the roof leak. Make sure that the roof sheathing hasn’t rotted or that other less obvious problems in your ceiling or walls haven’t developed. And then detail a comprehensive plan to fix the damage. But more importantly, solve the problem.

Solutions

The damage caused by ice dams can be controlled in 2 ways: Maintain the entire roof surface at ambient outdoor temperatures or build a roof so that it can’t leak into sensitive building materials if an ice dam forms.

Cold roofs make a lot of sense. Here you let the cold outdoor air work for you. Keep the entire roof as cold as the outdoor air and you solve the ice-dam riddle. Look at the roof of an unheated shed or garage, a pile of lumber or an abandoned home. Ice dams don’t form on these structures because there is no uneven melting and freezing!

For new construction it’s easy. Design the house to include plenty of ceiling insulation, a continuous air barrier separating the living space from the underside of the roof, and an effective roof ventilation system. Insulation retards the conductive flow of heat from the house to the roof surface. An air barrier retards the flow of heated air to the underside of the roof. And a good roof-ventilation system helps keep the roof sheathing cold. In an existing house this approach may be more difficult to follow. Often you are stuck with less than desirable conditions. But let’s look more closely at all the issues that will guide your strategy.

Insulation: Houses in the northern United States should be equipped with ceiling insulation of at least R-38 (about 12 inches of fiberglass or cellulose). The insulation should be continuous and consistently deep. The most notable problem area is located above the exterior wall. Raised-heel trusses or roof-framing details that allow for R-38 above the exterior wall should be used in new construction. In existing structures, where the space between the wall’s top plate and underside of the roof sheathing is restricted, install high R/inch insulating foam (R-6/inch). Be sure to seal the insulation at this point to prevent warm-air leakage from the living space.

Ventilation: A soffit-to-ridge ventilation system is the most effective ventilation scheme you can use to cool roof sheathing. Power vents, turbines, roof vents and gable louvers just aren’t as good. Soffit and ridge vents should run continuously along the length of the house. A baffled ridge vent (like the one sold by Air Vent) is best because it will exhaust attic air regardless of wind direction. The exhaust pressure created by the ridge vent sucks cold make-up air into the attic through the soffit vents. A 2-inch space or “air-chute” should be provided between the top of the insulation and the underside of the roof sheathing in all applications. The in-coming “soffit” air washes the underside of the roof sheathing with a continuous flow of cold air. CAUTION: Be sure to install insulation baffles above the exterior wall to protect the insulation from the air that blows in through the soffit vents.

Air Leakage: Insulation retards conductive heat loss, but a special effort must be made to block the flow of warm indoor air (convection) into the attic or roof area. Small holes allow significant volumes of warm indoor air to pass into attic spaces. In new construction avoid making penetrations through the ceiling whenever possible. But when you can’t avoid making penetrations or when you need to air-tighten existing homes use urethane spray-foam (in a can), caulking, packed cellulose, or weatherstripping to seal all ceiling leaks like:

  • wire penetrations
  • plumbing penetrations
  • ceiling light fixtures
  • attic hatches
  • chimneys
  • bathroom exhaust fans
  • intersection of interior partitions and ceiling

Contact a Minnesota roofing contractor to do an in-home evaluation to diagnose the performance of your home and together decide what the best course of action is for your situation.

Commercial TPO Roofing — Single Ply Roofing Systems

December 9, 2010

Commercial TPO Roofing — Single Ply Roof System

JM TPO is one of the latest single ply, flat roofing materials on the market.  The current membrane formulations are reinforced with a polyester fabric and manufactured using an ultraviolet-resistant thermoplastic polyolefin formulation.  TPO from JM comes in several thicknesses.  It is designed for use in mechanically fastened and adhered roofing applications in new, re-roof and re-cover roof constructions.  It is fire and chemical resistant and contains UV inhibitors for added longevity.

The Johns Manville TPO roofing systems combine both polypropylene (plastic) and ethylene-propylene (rubber) using state-of-the-art polymer manufacturing technology.  This results in an ideal commercial roofing system that is reliable, cost effective, environmentally friendly and easy to install.  The TPO systems can be installed fully adhered or mechanically fastened.

United Roofing & Remodeling is proud to carry and install the Johns Manville TPO system. We carry two types of TPO roofing products, TPO and TPO-1.  Both come in several thicknesses, please call us for a free consultation and needs assessment.

Call a reliable Minnesota roofing contractor today Or Request a Quote online

Protecting Your Minnesota Home From Ice Dams This Winter

November 9, 2010

Protect Your Home From Ice Dams

What Is An Ice Dam?

Ice dams are formed when heat from inside of a home escapes into the attic and warms the roof decking during the winter.  The heat, combined with the heat from the sun, can melt snow on the roof.  Melting snow on the upper roof and in the valleys runs down toward the eaves as water.  When it reaches the cold eaves and gutters it freezes.  This continuous thaw and re-freezing process creates an ice dam.  The result is water backing up under the roof shingles or behind fascia boards where It can soak through the roof decking or wall sheathing, causing tremendous damage to attics, ceilings, and walls.

Ice Dam Defense
There are 3 ways to defend against the damage ice dams cause.  All 3 work together.

  • Insulation/ Insulation keeps heat from escaping from your home’s living space into your attic.
  • Ventilation/ Ventilation removes the heat and keep the roof deck evenly cool to help prevent snow from melting on the roof.
  • Water-proofing/Water-proofing is laid across the roof before shingles are applied and protects against dams that form on the roof.

With existing roofs, waterproofing underlayment is only an option if you remove the existing shingles or are building a new addition. Either way, increasing the insulation R-value in the attic is always possible, and ventilation can usually be added to your attic quite easily.

An energy efficient roof minimizes problems with ice dams.  Contact a professional roofing contractor to do an in-home evaluation to diagnose the performance of your home and together decide what the best course of action is for your situation.

Outstanding Beauty Of A Slate Roof

October 5, 2010

A Slate Roof For Outstanding Longevity & Natural Beauty

Why use slate?

Slate roofing can be applied to any permanent structure. The intrinsic beauty of slate will enhance any building from schools to homes, as well as commercial and government structures.  Slate’s extended life expectancy and durability creates a low cost of ownership.

Slate also provides these benefits:

Natural material

• Fireproof

• Waterproof

• Permanent

• Insulating factor saves energy

• Resists climactic change

• Impervious to fungi and mold

Slate contributes to design elegance through:

Color

• Thickness

• Surface texture

• Overall roof texture

Guaranteed to last one hundred years!

Slate Grades

Slate is “graded” according to the uniformity in thickness that each piece exhibits.  Since slate is a natural product, the more demanding the physical specification, the more the demanding production requirements.  Therefore, a slate’s grade has great bearing on the availability and overall cost of the material.

Important facts about slate…

Slate is a tried and true material for building a beautiful and very long lasting roof for any structure.  The 100 year life expectancy is no projection—it is the result of “field application”. There are thousands of slate roofs still in service today installed in the 1800’s!  With such a long history, many terms describing the material have been coined and over the years, and some have evolved into misinterpretation.  For example, a common misconception associated with the nomenclature of describing slate occurs when the terms weathering and fading are erroneously interchanged.  Here’s the clarification:

Nomenclature of Blue Black & Black Slates

Fading

The term fading refers to certain slates, that after prolonged exposure to the elements, exhibit a chalk-ashen residue on the exposed surface of the slate.  The chalk-ashen residue is the result of a chemical reaction and the associated release of calcium from the body of the slate.  This release weakens the structure integrity of slate and is detrimental to the slate’s life expectancy.  The term is most often used in conjunction with the Blue Black or Black slates of Pennsylvania and Virginia.

Non-fading or Unfading

The term refers to certain slates that after a prolonged exposure to the elements do not produce the chalk-ashen residue.  Non-fading or Unfading slates usually have greatly extended life expectancies over those slates prone to calcium release.

Classification of Colored Slate

Colored slate does not fade, but it will experience varying degrees of color change.  This weathering of slate is due to the oxidation over time of minerals embedded in the slate.  Depending on mineral content, the weathering process slowly changes the slate color.  The color change is often a movement toward buff, brown, gray or tan.  This surface oxidation is not detrimental to the slate’s structural integrity and does not shorten the life of a roof.

Colored slates are classified in three types.  This classification is based upon the degree of color change  over time:

Weathering

The term refers to slates that will exhibit the largest number of individual pieces that will transform from the original color to an earth tone.

Non-weathering

The term refers to slates that exhibit the least amount of color change.

Semi-weathering

The term refers to roofing slates that are manufactured from slate that has varying mineral content.

Some of these slates will undergo a color change while others remain their original shade.  The percentage of semi-weathering slates that will experience color change is variable depending upon the location in the quarry from which the slate was extracted.

If you would like more information, contact a Minnesota roofing contractor that is experienced in slate roof installation.