Los Angeles County, California

Roof and Attic Ventilation in Los Angeles

A hot attic ages a roof from underneath, and most attics that fall short are short at the eave, where the air is meant to come in. We check the attic and the roof together, and you pay nothing for the inspection or the written quote.

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We come out, get on the roof, and tell you what we find.
The price in writing
A written quote before anyone starts, with nothing to sign on the spot.
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Our roofer who comes out holds a current California license.
Across Los Angeles County
From the Valley and the foothills to the Westside and the South Bay.

Roof and attic ventilation is intake vents low on the roof and exhaust vents high on it, cut and flashed into the roof plane. It runs on warm air rising, with no motor. The moment to fix it is the re-roof.

What it isPassive intake low on the roof and exhaust high on it, cut into the roof plane
How much1 square foot of vent per 150 of attic, or 1 per 300 where it is split high and low
When to do itWith the re-roof, because the vents go through the covering
In a fire zoneVents listed by the State Fire Marshal, or tested to ASTM E2886

This is the most common ventilation fault in Los Angeles and it is invisible from the roof. Insulation pushed into the eave blocks the intake, so the exhaust up at the ridge has nothing to pull.

How a vented attic works

Air comes in at the eave, runs up the underside of the deck and leaves at the ridge. The channel above the insulation is the whole mechanism, and it is the part that gets blocked.

Hot air leaves through exhaust vents near the ridge and air is pulled in at the eave to replace it, the way a chimney draws. Attic heat ages the covering from below while the sun works on it from above, and venting brings roof temperatures down in a hot climate.

How much venting an attic needs

1/150 is the baseline.One square foot of net free ventilating area per 150 square feet of attic.
1/300 has to be earned.It takes 40 to 50 percent of the required area from ventilators in the upper portion of the attic, at least 3 feet above the eave or cornice vents, with the balance at the eave or cornice. It carries a vapor retarder condition in some climate zones, so ask your building department before sizing at 1/300.
Openings have a size band.The least dimension runs from 1/16 inch minimum to 1/4 inch maximum, and anything larger gets screened inside that band.

Net free area

Net free area is the open space in a vent that air can pass through. Screens and mesh cut into it, so the air path is smaller than the hole. The rating is on the manufacturer's data sheet, and plan check asks for it. Multiply the rated area of one vent by the number of vents and hold that against the attic square footage.

Venting a tile roof

Tile vents at the ridge under the cap tiles. The mesh is what keeps embers and birds out, and on a tile roof it goes in while the ridge is open anyway.

A barrel tile roof will not take a ridge vent the way a shingle roof does. The exhaust goes in as low-profile vents set into the tile field near the ridge, and the intake comes in at the eave under the first course. They get cut and flashed in while the tile is off, so a lift and relay is the cheap time to add them.

What it isPassive intake low on the roof and exhaust high on it, cut into the roof planeThe inspection is free, and the price for your roof comes in writing.

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Balancing intake against exhaust

Intake should be 50 to 60 percent of the net free ventilation area and exhaust 40 to 50 percent, and intake should never be less than exhaust. Most attics that fall short are short at the intake. A ridge vent starved of intake pulls make-up air from itself and can draw in weather.

Two kinds of exhaust over one attic

Two types of exhaust vent over one attic short circuit each other, and combining them goes against the manufacturers' instructions. The air takes the short way between the two openings, and the second one starts working as an intake for weather and debris. The common version on an LA re-roof is a new ridge vent over the decorative gable vents of a 1920s house, with nobody closing the gables off.

The eave is where it usually fails

Blocking, bridging and insulation must not block the free flow of air, and a 1 inch space has to be left between the insulation and the roof sheathing. A house can have soffit vents down both eaves and no air moving above, so the eave gets looked at first. Opening a packed eave back up and holding it open with baffles is insulation work, a separate trade on a separate ticket. What we look for in an attic is on the roof inspection page.

Vents in a high or very high fire hazard severity zone

In a high or very high fire hazard severity zone the vents fall under the California Wildland-Urban Interface Code, which replaced Chapter 7A on January 1, 2026. They have to be listed by the California State Fire Marshal or tested to ASTM E2886. The Class A fire rated roofing page goes through it vent by vent.

What the warranty says about venting

GAF's limited warranty states that failure to install adequate ventilation is not covered. CertainTeed shortens the term and drops SureStart coverage where it considers the deck inadequately ventilated. A defect in the shingle itself is still covered. Read the warranty for the shingle going on your roof.

What to ask your roofer

What attic area did you measure, and are you sizing at 1/150 or 1/300?
What is the rated net free area of each vent, and how does intake split against exhaust?
Does any old exhaust vent stay open once the new ones go in, and is the eave path clear?

Put those answers in the written quote. The roof replacement page covers the rest of the job, and you can ask for a quote when you are ready. Roofing work in California takes a roofing license, and any license number can be checked on the CSLB website.

The offer

$500 off a new roof, 10% off any repair

Send your request online from this page and the offer is attached, with nothing to remember.

We get on the roof, and into the attic if that is where the answer is
You get photographs of whatever we find
The price in writing, with nothing to sign on the spot

Claim it on a free inspection

Ember-resistant ventsIn a high or very high fire hazard severity zone the vent itself has to be listed or tested.
The intakeExhaust at the ridge does nothing without air coming in low at the eave.
Done with the roofVents are cut and flashed into the covering, so the re-roof is the moment.