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How Many Layers Of Roof Shingles Are Allowed In California

Is There Structural Damage

Installing Man-made Slate Roofing Shingles

If a roof has structural damage from a wind storm, exceedingly large snow load, hurricane or a tree falls on the roof, then permits are usually required to do the roof repairs.

Structural damage is generally considered more serious and may need a set of plans and an engineering review by the building department.

Leaking over the long-term: damaged roof sheeting, rafters or trusses.

Plywood or OSB roof sheeting can be badly damaged when exposed to moisture from slow and long-term leaks. Rafters and roof trusses may likewise suffer damage from these types of leaks. Wood rot and deterioration weakens framing members over time and some of the framing members may need to be replaced. Depending on the severity of damage, a permit may be required to repair and correct these problems.

When not repaired for long periods of time, wood rot and mold and mildew may develop.

Specialty Asphalt Roofing Shingles

Specialty shingles can come in bolder colors and styles thatmimic other roofing materials, such as tile or wood shake, and offer thepracticality and affordability of asphalt shingles with a slightly differentlook.

For example, Owens Corning® Roofing offers:

TruDefinition® Duration® architectural shingles in Terra Cotta have the deep clay color of tile with none of the hassles regarding extra weight distribution.

R9021 Roofing Covering Materials

Roofs shall be covered with materials as set forth in Sections R904 and R905. A minimum Class A, B or C roofing shall be installed in areas designated by this section or where the edge of the roof is less than 3 feet from a lot line. Class A, B and C roofing required by this section to be listed shall be tested in accordance with UL 790 or ASTM E108.


  • Class A roof assemblies include those with coverings of brick, masonry and exposed concreteroof deck.
  • Class A roof assemblies include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile, or slate installed on noncombustible decks.
  • Class A roof assemblies include minimum 16 ounces per square foot copper sheets installed over combustible decks.
  • Class A roof assemblies include slate installed over underlayment over combustible decks.
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    Deadline Nears For Residents To Replace Wood Roofs

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    With the 20-year period for replacing all-wood-shingle roofs with less fire-prone material nearing its Aug. 14, 2012, deadline, 128 homes have yet to make the transition.

    The drumbeat to shore up the last of the holdouts is expected to get louder as the deadline looms, with fire officials espousing the benefits of replacing the roofs.

    Wood shingles are a pile of kindling on your roof, said former Burbank Fire spokesman Ron Bell. It was a great material back in the day, but its past its time.

    But with households still struggling under the weight of the protracted recession, some on the City Council may opt to extend the deadline further for a project that could run well past $10,000.

    Councilman David Gordon said in an email that the city should consider modifying, extending or suspending the reroofing period.

    I intend to call for an additional agenda item to come forward without delay to allay the threat of unbearable additional expense currently hanging over many law-abiding Burbank homeowners, Gordon said. may not have the means to afford replacing their otherwise perfectly functional and historically safe roofs still in good repair.

    Gordon said he was told the price could be as high as $40,000 for more unique roof shapes.

    Low-interest loans from area banks are listed on the citys website, and a loan through the Redevelopment Agency is also an option.

    Its dangerous to you, your neighbors, your family and your guests, Bell said.

    How Many Layers Should A Flat Roof Have

    Asphalt Roofing Shingle Installation Audry Way El Cajon ...

    Most residential roofs are steep-slope roofs. That means they have a noticeable pitch or angle. By contrast, most commercial roofs are low-slope, or flat. That flat roof over your head is more complex than you might imagine. First, it isnt truly flat. Second, it could have a surprising number of layers.

    Read Also: How Much Should I Pay For A New Roof

    Reasons Not To Put Shingles On Top Of Shingles

    However, when it comes to a re-roof, overlaying shingles has become a method of the past. While a repair job can often be more convenient and somewhat more cost-efficient, placing new shingles over old ones is never a good idea.

    Whether repairing one section of roof, or a replacing a whole one, its always best to pull up the old shingles before putting down the new ones.

    Roof Over: Roofing Repairs

    The time has come for a new roof and theres a decision to make whether to tear off the old asphalt roofing and replace it or add new asphalt roofing over the existing material. It can be a dilemma, but with a few helpful tips covering the pros and cons, youll have the information needed to make the right decision.

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    Roofs In High Fire Risk Areas

    Homes built in areas that are considered high fire risk areas generally must meet higher standards and code requirements. Wildfire areas are invariably associated with strong winds and convection columns when fires occur and generally roofs on these homes require higher fire ratings and special installation therefore, building departments are more likely to require permits for major repairs and reroofing projects in these areas.

    Homeowners may be required to upgrade the fire rating of their roofs as well as change the types of roof vents and other penetrations to resist heat and embers.

    Questions To Ask When Hiring A Roofer

    Top Questions to Ask When Hiring a Roofing Contractor

    Whether you are undertaking roofing for a house or other building, you want to make sure you hire a roofer who is not only licensed, but who is knowledgeable with California roofing codes. Not hiring the right roofer can be a disaster for your home or building and lead to a lot of extra costs down the road, especially if the roof violates your local roofing permit requirements.

    Here are some questions to ask when hiring a roofer:

    • What is your license number?
    • What is your labor warranty?
    • Can I contact your insurance carrier to confirm you have liability and workmans compensation coverage?
    • Can I have the name of two or three people youve done projects for?
    • Are there roofs youve done in my neighborhood that I can check out?
    • What are you going to replace on the roof and what materials will you be using?
    • Can I see some samples of the shingles that will be installed?
    • How will the job site look at the end of each day?
    • How long will it take to roof the building?
    • What is the cost of any wood that may need to be replaced?
    • Do you do solar paneling and what is the cost?

    Since you are likely to put a new roof on your house only once during the time you own it, you want to make sure you do it right. Get a referral when you can, and be sure to do your research. You want a contractor who is both a stickler for California roofing laws and who can give you the look you want on your property.

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    R90212 Roof Coverings Within State Responsibility Areas

    The entire roof covering of every existing structure where more than 50 percent of the total roof area is replaced within any one-year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of the roof of every existing structure, shall be a fire-retardant roof covering that is at least Class B.

    Exception: Areas designated as moderate fire hazard severity zones.

    City Or County Building Codes

    Determining how many layers of roofing material installed on your home or business is at the top of the list of things to do. There was a time, in the past, when multiple layers of asphalt roofing material were allowed. Today, most cities only allow no more than two layers of asphalt material.

    Do an inspection of your roof or hire a roofing contractor to tell you how many layers of asphalt your roof has. If its more than two layers of shingles, chances are good youll need to do a complete tear-off. To verify what the restrictions are regarding roof replacement, contact the local building and permit department of your city to ensure you are in compliance with your regions building codes.

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    Two Layers Is Too Many

    Not many people would argue with the idea that quality trumps quantity. Most roofers would agree that adding a second layer to your roof is NOT a good idea and cuts back on the quality of the roof. Yet we still run into homes with 2 or more layers on a fairly frequent basis. Why is this?

    Unfortunately, many homeowners opt for adding a second layer of roofing because the immediate cost is much less than completely tearing off and replacing the existing roofing. What they dont see, however, is the long term cost. While it may seem that two layers of roofing equals twice the protection, this is in no way true. Quantity does not equal quality. Heres why:

    A) Foregoing the cost of tearing off the old shingles means that you are also foregoing a chance to inspect the underlying materials. While shingles are the part of the roof we think about the most, a roof is not just made of shingles. Decking, underlayment, flashing, etcall lie below the shingles and are just as important. When you fail to remove the shingles and inspect these materials when installing a new roof, you miss the opportunity to catch weak points. These weak points include rotting plywood, tears in the underlayment, or rusted flashing. All of which can cause unexpected, and costly damage. The longer they go unrepaired, the high the chance they will develop into leaks, cave ins or mold.

    How Many Layers Of Shingles Are Allowed On A Roof

    Can you guess how many layers of shingles are on this roof ...

    December 18, 2019 By Taylor-Made Roofing

    Signs that your roof has reached the end of its life are typically fairly obvious: consistent leaks, shingle loss, and mold growth can all point to the need for a new roof. Some homeowners may assume that a roof replacement means completely stripping off the existing roof. However, thats not always the case. If your roofs sheathing and shingle structure are both largely intact, some roofers will apply a new layer of roof shingles right over your first layer. This can be a quick, cost-effective option. The question is, how many layers of shingles are allowed on a roof?

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    R90211 Roof Coverings Within Very

    The entire roof covering of every existing structure where more than 50 percent of the total roof area is replaced within any one-year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of the roof of every existing structure, shall be a fire-retardant roof covering that is at least Class A.

    Exception: The requirements shall not apply in any jurisdictionthat adopts the model ordinance approved by the State Fire Marshal pursuant to Section 51189 of the Government Code or an ordinance that substantially conforms to the model ordinance and transmits a copy to the State Fire Marshal.

    So How Many Layers Of Roof Shingles Are Allowed

    In some instances, 3 layers may be allowed, but this is rare. Most areas only allow for a maximum of two layers. This will also be constrained by other factors. The contractor may do a walk on the roof and also inspect from the attic for any rot before installing a second layer of shingles. If there is rotted wood, this would need to be replaced before any further roof repair work is undertaken.

    The roof needs to be able to bear the weight of two layers of shingles plus be able to bear the added, weight in winter due to a layer of snow, without the framing being stressed to breaking point. Laying a second layer over the current layer of shingles means that longer fasteners need to be used to anchor them down. This is also why three layers would generally be impractical.

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    Los Angeles County Cool Roof Code Requirements

    Second, for the unincorporated areas of Los Angeles County, asphalt shingles must meet or exceed an SRI value of 20 for all new construction and reroof applications in residential and commercial buildings. This is also a mandatory requirement per the Green Building Standards Code of Los Angeles County.

    How To Lay Shingles

    Renovation Phase 1: Concrete Slab Roof Replacement

    This article was co-authored by David Bitan. David Bitan is a roofing professional, licensed contractor, and the owner and founder of Bumble Roofing based in Southern California. With over 12 years of construction industry experience, David specializes in restoring, repairing, and maintaining residential, commercial, and industrial roofs. With over 60 years of combined experience, Bumble Roofing provides easy, friendly services to structures including residential, commercial, industrial, multi-family, and government buildings along with hospitals, hotels, and churches.wikiHow marks an article as reader-approved once it receives enough positive feedback. In this case, 90% of readers who voted found the article helpful, earning it our reader-approved status. This article has been viewed 645,424 times.

    Shingles protect sloping rooftops from the effects of rain, snow and hail while providing an attractive crown for the house. Keeping a solid roofing layer of shingles is an important way to avoid water damage and leaks. Doing it properly will keep you without problems for 20 or 40 years. Laying shingles can be hard and hot work, but the reward of an attractive, watertight roof can be worth it.

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    Start Your California Cool Roofing Project Today

    Ready to take the next step towards building an energy-efficient home? Whether youre embarking on a reroofing project or adding the finishing touches on your newly constructed house, Owens Corning Roofing can help.

    Owens Corning® COOL asphalt roofing shingles meet various levels of California COOL roofing requirements in a great selection of colors that complement many home exteriors.

    Be sure to take advantage of Californias incentive programs for home and business owners who use COOL roofing materials.

    Your Home: Can A Multiple

    Question: If I have more than one layer of roofing on my home, should I be concerned about resale?

    The short answer is yes.

    Now for the why.

    If there is one thing that I love about my industry it is that things are constantly changing. And roofing guidelines are no exception to the rule. When I started my real estate career, I sold homes with three layers of roofing. Sometimes even with composition shingles over wood/shake shingles. It used to be common practice to install one layer of roofing over another.

    Well those days are gone. As the years have passed, the insurance guidelines and the city guidelines have changed dramatically. Also, we have learned more about attic ventilation and how multiple layers of roofing actually compromise the life of the roof because of poor ventilation and the extreme temperature changes that we see from summer to winter.

    So back to that short answer of yes. We are really talking about two different issues: multiple layers of composition roofing and composition over a wood shingle/shake roof.

    In the case of composition over shake shingle, it is virtually impossible to obtain insurance for a home purchase these days. There are only two companies that know of that will offer coverage. And as mentioned earlier, they will only cover the top layer. And in some cases, the buyer will have to pay a higher premium.

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    Understanding Solar Reflectance Index

    COOL roof code requirements in California are based on the Solar Reflectance Index .

    Various materials can be assigned an SRI value ranging from 0 to 100.

    • The lower the SRI value, the hotter the material is likely to become in sunlight.
    • Material with a higher SRI value will stay cooler in sunlight.

    For roofing materials, SRI is a calculation using the aged solar reflectance and thermal emittance measurements of the asphalt shingles materials. It ranges from 0 to 100. This measurement can be used as an indicator of how hot shingles are likely to become when theyre exposed to the sun.

    • The lower the SRI value, the hotter the asphalt shingles are likely to be in sunlight.
    • Conversely, roofing shingles with a higher SRI will help reduce the cooling load on your home.

    Why Not Add New Roof Shingles Over Old

    Asphalt Roofing Shingle Installation Audry Way El Cajon ...

    As suggested above, the potential cons of re-roofing tend to outweigh the potential pros, but it all depends on your situation. The following list includes some universal reasons not to reroof as well as some considerations or things to check out if you’re seriously considering adding new roof shingles over old ones.

    1. Shingles are designed for flat surfaces. They don’t do a good job of bridging over gaps, dips or humps, including the stepped texture created by overlapping shingles. Re-roofers have tricks to lay new roof shingles over old so that the same step-ups between courses are maintained, but if any old shingles are cupped, curled, or otherwise misshapen, those defects will “telegraph” through to the new layer. Many roofers recommend using laminated, or dimensional, shingles for re-roofs because they’re thicker than standard shingles and often have a staggered edge profile that helps hide any dips or high spots in the old roofing.

    3. No visual inspection of roof sheathing. Without a tearoff, roofers can’t see what the decking looks like. A good roofer will perform a careful “walking” inspection for spongy areas and other problems, and they can make localized repairs before re-roofing. A not-so-good roofer might be less conscientious.

    5. Re-roofing may affect the warranty on the new shingles. Pretty self-explanatory. Be sure to check with the shingle manufacturer regarding all warranty issues and installation requirements before re-roofing.

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