# How much ventilation does a roof need?

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How Many Vents Do I Need? The general rule of thumb in these situations is of roughly one vent per every 300 square feet of attic area if the attic has a vapor barrier. If not, there should be one vent for every 150 square feet. You will need to have 1 square foot of vent area for every 150 square feet of attic space.

## Can a roof have too much ventilation?

Dangers of Too Much Ventilation

The two main dangers associated with too much ventilation involve roof damage and increased utility bills. If you have too much air circulating, your roof will collect moisture causing damages that will weaken spots and then cause leaking.

## What happens if a roof is not vented?

They say that poor or non-existent ventilation might cause attic temperatures to rise to 150 degrees or higher in the summer. That can lead to damaged shingles and other roofing materials as well as a buildup of condensation and development of mildew and mold.

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## How do I calculate roof ventilation?

Attic sq.

To calculate proper intake ventilation for the power vent, divide the CFM capacity of the power fan by a factor of 300 and then convert to square inches. For example: • 1400 CFM power fan ÷ 300 = 4.6 sq. ft.

## What is proper roof ventilation?

Roof ventilation is based on the simple fact that warm air rises. … In winter, heat from your home warms attic air. In either season, good venting occurs when cool air can enter the attic near the eaves and exit near the peak. Ideally, half of the vent area should be low and half high.

## How do you fix poor roof ventilation?

If this high-pressure air is given an outlet to escape, it will automatically be replaced by cool, low-pressure air. By installing various types of roof vents, homeowners can take advantage of natural air flow to provide proper roof ventilation and keep the inside of the home comfortable.

## Does roof need to breathe?

Moisture in the attic area can cause roof shingles to buckle and insulation to lose its effectiveness. It also creates an environment that is conducive to mildew. In short, you need proper attic ventilation to help: Prevent structural damage caused by moisture.

## Do I need a vented roof?

Roof vents prevent damage to your shingles. Without proper roof ventilation, you allow the attic to remain at a high temperature. This can damage and crack your shingles well before they should be showing signs of damage.

## What happens if you don’t vent attic?

Without ventilation, the attic will be warmer than the outdoor temperature, causing snow that lands on the roof to melt. As it drips down to the bottom of the roof, it will refreeze, forming dangerous ice dams. These can cause serious damage to your roof and gutters.

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## Is Roof venting required by code?

Enclosed attics and enclosed rafters are required by the California Residential Code to have proper ventilation.

## What type of roof vents are best?

In most cases, we recommend soffit vents for intake and a ridge vent for exhaust. For homes that cannot have a ridge vent, box vents are generally the second best option for exhaust. And for homes that cannot have soffit ventilation, you will find that fascia vents to be your second best bet.

## How do you tell if your attic is properly ventilated?

How to determine whether you need better attic ventilation

1. Look at your eaves and roof. …
2. Touch your ceiling on a warm, sunny day. …
3. Thick ridges of ice on your eaves in winter are a sign of poor attic ventilation. …
4. Warm air that escapes living space also carries moisture that will condense on rafters or roof sheathing.

## What are the different types of roof vents?

Harmony Home Improvement, one of the top home improvement contractors in Connecticut, lists the five different types of roof vents.

• Ridge Vents. These are installed on the peak or ridge of the roof, hence the name, and are completely covered by the shingles. …
• Soffit Vents. …
• Cupola Vents. …
• Powered Vents. …
• Gable Intake Vents.

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## Can I have too much ventilation in my attic?

It’s possible to have too much exhaust ventilation, but you cannot have too much intake ventilation. If there is more intake ventilation than the attic’s square footage requires, it’s not problematic because any excess intake converts to “exhaust” on the leeward side of the house.

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## Is it OK to insulate roof rafters?

Insulating between rafters will do no good, because the attic should be ventilated, and the rafter insulation would be between two unheated spaces. … Moisture buildup in the attic is a concern because it can condense into water, often causing mold. Good ventilation, from soffit vents and a ridge vent, will stop that.

## Does a porch ceiling need to be vented?

Because porches are often open and unconditioned, venting a porch roof for that reason is not usually necessary. The most common argument in favor of porch roof vents is that venting hot air from under the roof increases the life of shingles on the roof.