Hot Attics Destroy Roofs, But Ventilation Can Help

It’s not just older homes that have roof issues — newer homes with inadequate attic ventilation can run into moisture, mold and ice dam problems.

Jeff Brett, the owner and CEO of King Quality Construction, recently shared the top complaints that homeowners have when it comes to their roofs in winter and identified the causes behind those issues.

King Quality Construction, based in Bohemia, is the largest siding, window and roof installer on Long Island. The company is also the largest GAF dealer in the Northeast; GAF is the biggest roofing manufacturer in North America.

Mr. Brett said roofing has changed dramatically in the last 15 years or so as homes have become more efficient. He explained that as homeowners add insulation and replace windows, it’s great for reducing a house’s energy costs and environmental impact, but it can create problems for the attic and roof.

“The more you insulate, the more mold, the more moisture, the more condensation you get in your attic — unless you do the roof differently,” he said.

Homeowners may see rusty nails creating black spots on the underside of their roof and automatically think the problem is a leak, Mr. Brett said, but that’s often not the case.

“Most of the time, it’s really not a leak. It’s really condensation because the attic’s not vented properly,” he said. “Homes in the old days used to breathe all over the place: They’d breathe through the windows, they’d breathe through the doors. They didn’t have lots of insulation.

“Now, people are making the house airtight. So what happens is all that hot air rises up and settles in the attic.”

Hot attics create the biggest problems in winter, when the temperature difference between inside and outside is greatest. “It’s freezing outside. You turn your heat up. You have brand new windows and insulation, so the heat doesn’t escape through the home,” Mr. Brett said. “But it’s gotta go somewhere, so it goes up into your attic.”

When there is snow on the roof and the attic is hot, “it causes condensation in the attic, which rots out the plywood, can cause mold and other problems, and can destroy your roof,” Mr. Brett said.

The attic does not need to be 90 degrees to create an issue, he noted. Just 70 or 80 degrees will do it when temperatures outdoors are freezing.

The contrast in temperature can also lead to ice damming, when gutters become blocked and water will possibly leak inside a home. “It’s probably one of the biggest complaints of the homeowner,” Mr. Brett said of ice damming.

Keeping gutters clear of leaves and other debris can help prevent ice damming, but clogged gutters are not the only factor that contributes to ice dams.

Snow on the middle of a roof melts when the attic is hot, and then runs down to the edge of the roof, where ice builds up, preventing water from running off the roof. “The water can’t go anywhere, so it goes into your house,” Mr. Brett said. “It is a helpless feeling because there’s nothing you can do about it, and the water just starts coming in.”

Signs of an ice damming issue include rotting fascia and gutters pulling off the house.

“When the fascia board is rotted or the gutters are falling off, it’s not a gutter issue, … it’s a roof issue,” Mr. Brett said. “It’s really something you have to address, because roofing issues don’t get better, they don’t go away — they get worse.”

To resolve moisture and ice damming problems, an attic needs a ventilation system, which can be a passive system or an active system.

A passive system takes advantage of the fact that hot air rises. Such systems involve a ridge vent and soffit vents working in concert. The ridge vent on the top of the gable lets hot air out. That’s the outtake, but it can only work if there is an intake as well.

Mr. Brett said the biggest mistake roofers and homeowners make is to think that an outtake alone is good enough. “But, really, hot air cannot leave without new air coming in. … To let air leave, you must replace it.”

So for every 1 foot of outtake on the ridge, 2 feet of intake is needed on the soffits, which are the underside of the roof overhang.

Mr. Brett noted that sometimes people install insulation on top of the soffit, which stops the airflow. That insulation should be removed to allow soffit vents to do their job.

For houses that don’t have soffits, an intake vent can be installed near the gutter edge, Mr. Brett said.

Active systems are much stronger than a passive system, according to Mr. Brett. They include a fan that blows air out of the attic. Some attic fans turn on automatically based on temperature, and newer models also include humidistats to turn on when the moisture level in the attic is high.

But active systems still need an intake. Otherwise, Mr. Brett said, the fan will suck all the heated air out of the house in winter.

Mr. Brett finds himself having to explain to people that letting the heat out of the attic in winter will not affect the heat inside the home or cause heating bills to rise.

“Your heat’s going into your attic — you don’t live in your attic, you live in the main space. So insulating your ceiling, that’s really good for your roof and that’s good for your heating bill,” he said.

“Getting the roof done right the first time is the most important thing,” Mr. Brett said.

Twenty years ago, it was common practice to do a layover roof, which is just putting new shingles right on top of the old, and it was a job that sometimes homeowners could do themselves with a few friends, he said.

Part of the reason layovers were common was because of all the work it takes to rip off an old roof. But King Quality Construction hasn’t done a layover roof in many years. Mr. Brett said that’s because a new layer of shingles doesn’t fix all of the issues the roof had before.

Today, King Quality Construction rips off all the old shingles and uses a seven-part system when putting on new roof.

Homeowners tend to think only of what they can see — the shingles — but there is more to a roof. “What goes under their roof is just as important as what goes on it,” Mr. Brett said.

One part of the roofing system is Deck-Armor, an underlayment that is 15 times more breathable than tarpaper, so it lets moisture out while keeping rain from getting in.

A WeatherWatch rubber seal is installed around the perimeter of the roof by the gutter edge, in combination with a drip edge, to ensure that wind-driven rain and water from ice dams will not enter homes.

In the North, the ridge vent of choice is the Cobra Snow County, which prevents snow from blowing into the attic.

King Quality Construction also uses copper flashing around chimneys, instead of tar, which is prone to cracking and can leave a roof susceptible to leaks.

Mr. Brett recommends using the best products in combination with certified contractors. “You can use the best product, but if it’s not installed properly, there’s no telling what’s going to happen,” he said.

A roof used to last, on average, seven years, Mr. Brett pointed out. But today, GAF will guarantee both roof components and the roofer’s workmanship for 50 years when using a GAF-certified Master Elite contractor and qualifying shingles and accessories. And for South Fork houses on the water, where nor’easters blow, new HDZ shingles have a wind rating of “infinity,” he said.