A hot attic shortens a roof's life because it cooks the shingles from below. On a summer day in North Texas, the sun heats the roof from the top. If the attic under it has no way to breathe, the heat builds up there too, and the shingles get baked from both sides. They dry out, curl and lose their grit sooner than they should. Good attic ventilation (vents that let air move through the attic) lets that heat out. Cool air comes in low, near the edge of the roof, and hot air leaves high, near the peak. When that flow works, the roof runs cooler, stays drier and lasts longer.
Why heat is hard on a roof
Most homes in Crowley, Fort Worth and Burleson have asphalt shingles. Shingles are made with oils that keep them bendable. Heat pulls those oils out over time. Once they are gone, the shingle gets stiff and starts to crack, curl or shed its grit (the small stone bits on top that shield it from the sun).
A roof in Texas already gets a lot of sun. A hot attic under it adds even more heat, day after day, for months. Over a well-vented attic, the same shingles often age more slowly.
It is not only heat: water too
An attic can also trap water in the air. Showers, cooking and the AC all add damp air to a house, and some of it rises into the attic. In winter, when a cold night follows a mild day, that damp air can turn to drops on the cold wood under the roof. Over time, that can lead to:
- Dark stains or mold on the roof deck (the wood boards under the shingles).
- Damp, flat insulation that does not keep the house warm or cool.
Air moving through the attic carries that damp air out before it can do harm.
How attic vents work
Hot air rises. If there is a way out at the top and a way in at the bottom, air will keep moving on its own.
- Intake vents let fresh air in low. They are most often in the soffit (the flat boards under the edge of the roof that face the ground).
- Exhaust vents let hot air out high. The most common kind is a ridge vent, a long, low vent that runs along the peak of the roof under a row of cap shingles. Others are box vents (small square vents near the top), turbine vents (the round ones that spin) and gable vents (vents in the walls at each end of the attic).
A roof needs both. Lots of exhaust with no intake is like a straw with the bottom pinched shut.
Common problems we see
- Blocked soffit vents. Insulation gets pushed or blown over the low vents, or the soffit was painted over. The intake is shut, so the whole system stalls.
- Too few vents. Some older homes in Arlington and Fort Worth were built with just a couple of small vents for a big attic.
- Mixing exhaust types. A ridge vent plus box vents plus a turbine on the same roof can fight each other. One high vent can pull air in through another high vent, and the low vents get skipped. Most roofs work best with one kind of exhaust.
- Vents left out after a reroof. A rushed crew may skip cutting the slot for a ridge vent, or cover old vents without adding new ones.
Signs your attic is not breathing
You can check a few things yourself:
- The attic feels like an oven. But if it is hard to breathe up there even in the late afternoon, airflow may be poor.
- Shingles age early. Curling, cracking or bare spots on a roof that is not very old.
- Stains or a musty smell. Look at the wood above you with a flashlight on a sunny day.
- Ice or frost on the nails. On a cold morning, frost on the nail tips in the attic means damp air is stuck up there.
- You can not see daylight at the soffit. From the attic, look down to the edges. If insulation is packed tight against the soffit, the intake may be blocked.
Go into the attic only if you can do it safely. Step only on the wood beams, never on the insulation between them, and go in the morning before the heat builds.
How to fix it
Some fixes are small. Others make the most sense when the roof is being replaced.
- Clear the soffit vents. Baffles (small foam or cardboard channels set at the edge of the attic) hold insulation back so air can get in. This can often be done without touching the roof.
- Add intake. More soffit vents, or a vent strip at the roof edge, if the soffits are solid.
- Add or change exhaust. A ridge vent is usually added during a new roof, since the crew is already at the peak. Old box vents can be removed and patched so the system works as one.
- Send fans outside. Run bath and kitchen fan ducts out through the roof or a wall.
The right mix depends on your attic, your roof shape and how the house was built. A roofer should look at both the roof and the attic before saying what you need.
What it will not do
Be honest about the limits. Good airflow helps a roof last, but it will not undo hail damage or save shingles that are already worn out. It may help the house feel cooler and ease the load on your AC, but do not count on a big drop in your power bill. And more vents is not always better. Too much exhaust in the wrong place can pull in rain during a hard, windy storm. Balance matters more than the number of vents.
What to do next
If you are planning a new roof, ask what will be done about the attic vents. It is one of the questions in our post on what a good roof inspection covers. If your shingles are aging early, our roof replacement page shows how we handle vents on a new roof. Or call Legacy Roofing at (817) 602-2057. We work in Crowley, Fort Worth, Burleson, Mansfield, Joshua and nearby towns, and we will look at your roof and your attic and tell you plainly what we see.
