12 Roofing Myths That Cost Homeowners Money | Hommy
12 Roofing Myths That Cost Homeowners Money
The roofing industry trade association says there is no scientific evidence that algae damages shingles. People still get sold roofs over it. Here are 12 beliefs worth unlearning.
Hommy
July 17, 2026 · 11 min read
The asphalt roofing industry own trade association states plainly that there is no scientific evidence algae damages asphalt shingles. Homeowners still get sold full replacements over black streaks every year. That is the pattern with roofing myths: they are not harmless folklore, they have a price tag. Here are twelve worth unlearning.
Myth 1: You can just roof over your old shingles to save money
A second layer is legal in many places. A third essentially never is. Building code bans a roof recover outright where the existing roof is water-soaked or deteriorated, where the covering is slate, clay, cement, or asbestos-cement tile, or where the roof already has two or more layers of any type.
The bigger issue is what a layover hides and what it forfeits. It conceals deck rot, complicates proper nailing, and disqualifies the premium manufacturer warranties, which generally require a tear-off to the deck. You save money now and give up the coverage you were counting on.
Metal conducts electricity, but it does not attract strikes. What determines whether something gets struck is height and surroundings: hills, tall trees, taller buildings nearby. Roof material is not part of that equation.
If anything the risk runs the other way. Metal is non-combustible and gives current a low-resistance path to ground, so a struck metal roof is generally less likely to ignite than wood or asphalt.
Myth 3: A metal roof is loud in the rain
This myth comes from barns and sheds, where panels are screwed straight to open purlins with no deck, no underlayment, and no insulation below. That is genuinely loud.
A residential metal roof is a different assembly: solid decking, underlayment, an attic, and insulation. Measured differences against asphalt shingles in that configuration are small enough that most people do not notice. Your attic insulation does far more for sound than the roof surface does.
Myth 4: Insurance will pay for a new roof because the old one is worn out
This one is backwards. Age reduces what you get, it does not qualify you. Policies cover sudden damage from a covered peril. They exclude wear, aging, and deferred maintenance by design.
As roofs get older, many carriers move them from replacement cost to actual cash value, or apply a payment schedule based on roof age. The NAIC illustrates the gap with a worked example: two households, the same 15,000 dollars of roof damage and the same 1,000 dollar deductible. The replacement cost household nets 14,000 dollars. The actual cash value household nets 4,000 dollars after 10,000 dollars of depreciation.
Insurance rules vary by state, carrier, and policy, and they change. This is general information, not legal, insurance, or financial advice. Read your policy and talk to your carrier or state insurance department about your specific situation.
Myth 5: Dark shingles will wreck your energy bill
Roof color has a big effect on surface temperature and a modest effect on your annual bill. The EPA puts the residential cool roof benefit at an 11 to 27 percent reduction in peak cooling demand, which is not the same as your total yearly cost.
The Department of Energy is explicit that cool roofs help most in hot sunny climates on buildings with low roof insulation, and that a reflective surface is never a substitute for adequate insulation. In cold climates there is also a small winter heating penalty. Insulation, air sealing, and ventilation dominate the annual number. Shingle color is a second-order lever, so pick the color you like.
Myth 6: A few missing shingles means you need a whole new roof
Localized damage on an otherwise sound roof is a repair. Full replacement makes sense when damage is widespread, when the deck is compromised, or when the roof is near the end of its service life anyway.
The real constraint on a repair is color match. Shingles fade, and discontinued lines can force a larger scope than the damage alone would justify. That cuts both ways: in states with matching requirements in statute or policy language, an inability to match can obligate the insurer to fund a bigger replacement, which works in your favor.
Service life depends on material, installation quality, ventilation, and climate. Three-tab asphalt and architectural asphalt sit in different bands, and metal, tile, and slate outlast both by a wide margin.
Here is the part that catches people: the number printed on the wrapper is a warranty term, not a forecast. A "30-year" shingle is a warranty label. Real-world service life commonly lands under it, especially on a poorly ventilated attic.
This is the most expensive myth on the list, and the trade association is unusually direct about it. The Asphalt Roofing Manufacturers Association states that there is no scientific evidence that algae is damaging to asphalt shingles, although it certainly affects the aesthetics of a roof.
Those black streaks are algae, and they are cosmetic. The one functional cost is that they degrade the reflectance of a cool roof over time.
Moss is the different story. ARMA says moss can be detrimental to asphalt shingle performance: it lifts and curls shingle edges, raises wind damage risk, and in bad cases leads to deck damage and leaks. So treat moss, and do not let anyone sell you a roof over algae.
One more thing from ARMA: do not power wash. Use gentle or soft-wash methods, and expect recurrence, since bleach-based cleaning is temporary.
“Algae is cosmetic and moss is not. Getting that backwards is the difference between a wash and a replacement you did not need.”
The Hommy Team
Myth 9: More attic ventilation is always better
Ventilation needs to be balanced, not maximized. Code requires a minimum net free ventilating area of 1/150 of the vented space, reducible to 1/300 only when specific conditions are met, including that 40 to 50 percent of the area sits in the upper portion of the attic with the rest in the bottom third.
Adding exhaust without matching intake is actively harmful. More ridge or powered vents with no additional soffit intake creates negative pressure that pulls conditioned, humid air out of your living space through ceiling penetrations. That raises your bill and causes the attic moisture problem the vents were supposed to solve. Blocked soffits, usually insulation stuffed over them, are the most common failure of all.
Myth 10: A roof certification is the same as an inspection or a warranty
Three different things. An inspection finds current problems. A certification is a professional opinion that the roof is sound and should stay leak-free for a stated term, typically a few years, and it is mostly used in real estate transactions. A warranty is a service contract, a promise to pay for repairs.
The NRCIA frames the distinction as an assessment versus a service contract, and notes a certification is not a crystal ball that predicts future performance or covers unexpected damage. Buyers who treat a certification as coverage find out at claim time that it obligates nobody to fix anything.
Myth 11: You have to use the contractor your insurer recommends
Generally you do not. Consumer guidance from insurance regulators is consistent on this point: you may select a contractor your insurance company suggests, but you are not required to do so. Many states also have anti-steering provisions.
The honest nuance is that preferred-vendor work often moves faster on supplements, because the carrier already knows the contractor and their pricing. So it is a real tradeoff rather than a trap. Just know that the choice is yours.
Myth 12: Impact-resistant shingles always earn an insurance discount
Discounts are real, but they are discretionary and highly variable. They depend on state, carrier, and even ZIP code, and they usually apply only to the wind and hail portion of your premium rather than the whole bill.
Texas is the instructive case, because contractor marketing there often claims the state mandates a discount. It does not. The Texas Department of Insurance maintains a list of qualifying impact-resistant products, and insurers may offer a premium credit. No law requires them to. In a low-hail area, a Class 4 upgrade may never pay for itself.
And as covered above, Class 4 means resistant to cracking, not immune to denting, and cosmetic damage is frequently excluded from coverage anyway.
If a contractor tells you your state requires insurers to discount a Class 4 roof, treat the rest of their pitch with caution. Ask them to show you the rule. Then call your own carrier and ask what credit, if any, they actually offer at your address.
Bonus myth: a new roof adds its full cost back to your home value
Roofing recoups better than many projects, but not fully. The widely cited Cost vs Value report has put asphalt roof replacement well under 100 percent recouped, generally somewhere in the 55 to 70 percent band depending on the year and region, and the figure moves annually. Check the current year report rather than trusting a number in a blog post, including this one.
The better way to think about it: a new roof mostly prevents value loss. It removes a deal-killer at inspection and keeps the home financeable and insurable. That is worth a lot, and it is not the same as adding a dollar of equity per dollar spent.
