WHAT TO KNOW ABOUT ROOF VENTILATION – FAMILY ROOFING

Posted on by David Reid

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WHAT TO KNOW ABOUT ROOF VENTILATION

Roof ventilation is based on the simple fact that warm air rises.  In summer, the sun heats air in the attic. 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.  The hot air that accumulates in your attic can cause a variety of problems for your home.  It can cause your air conditioning system to work harder than it needs to, which can lead to higher energy bills.  It can also cause damage to your roof and shingles over time.

Roof ventilation is a term that may sound familiar, but not everyone knows exactly what it means.  So, when it comes to roof ventilation, there are three key things you need to know:

  1. It’s vital to prolong the life of your entire roofing system.

  2. Poor ventilation traps moisture which causes mold growth and water damage.

  3. Recurrent ice dams are caused by poor roof ventilation.

Roof Ventilation: Defined

Simply put, a roof vent will remove moisture and hot air from your attic.  However, there are many different types of roof vents that can remove moisture and heat in various ways.  But in the end, one thing is true: it’s critical to ensure your roof and attic stay at the right temperature and moisture-free.

Exhaust Vents: Remove Moisture and Heat

An exhaust vent is designed to remove hot air and moisture from your attic.  The most common type of exhaust vent is a ridge vent.  Ridge vents sit at the peak of your roof and ensure any hot air rising to the top of the attic has a place to escape.

Hot air contains moisture, so poor ventilation can create a very moist environment that can end up rotting and warping the wood in your attic.  Other types of exhaust vents include:

  • Off-ridge vents

  • Box vents

  • Hard-wired powered vents

  • Solar-powered vents

  • Roof turbines (whirlybird vents)

  • Cupola vents

Intake Vents: Bring in New, Fresh Air

An intake vent is designed to bring in clean, fresh air from the outside.  While exhaust vents are meant for removing moisture and heat, intake vents remove stale air that might be trapped inside your attic or roofing system and replace it with fresh outside air.  They can also help reduce temperatures which will lower cooling costs during the summer months.

The most common type of intake vent is your soffit vents.  The soffit along the eaves of your roof ensures a steady flow of air is always coming into your attic space. Other common types of air intake vents include:

  • Gable vents

  • Over fascia vents

  • Drip-edge vents

Both exhaust and intake vents work in tandem to create a consistent airflow that keeps moisture out, air circulating, and allows proper temperature control in your attic.

Ridge Vents

Ridge vents are popular for shingle roof houses, but options are available for all roofing types.  You install ridge vents on the roof ridge where the two slopes meet.

ridge vent baffles

Ridge vents fit along the entire length of the roof ridge, which means you’ll have a vent in the length of the roof. The ridge vent uses a small gap on both sides of the ridge to allow heat to escape.

The ridge vents fits over the space left between the two sides of the roof.  The ridge vents are hardly noticeable in terms of aesthetic appeal and look like part of the roof.  The vents are clad with the same material as the roof and thus blend perfectly into the roof design.

Ridge vents allow the free flow of hot, moist, and stale air out of the attic area while ensuring the roof’s integrity by keeping rainwater, debris, rodents, etc., out of the attic area.  Ridge vents are highly efficient as they don’t only have one exhaust vent.  The vent runs along the entire length of the roof ridge, thus ensuring no dead spots in terms of expelling unwanted air.

Ridge vents are exhaust vents and therefore need to be installed together with inlet vents to ensure you can optimally utilize the ridge vents’ design features.

Why Install A Ridge Vent?

The main reasons that ridge vents are the best include:

  • To ensure that the hot air trapped in the attic has the means to escape.

  • Air in enclosed areas heats up during sunny days, which causes adjacent rooms to heat up.  The unit will need to work harder to cool the house down if you’re using an air conditioner.  Vents allow the hot air to escape, lowering the ambient temperature and saving you money on air conditioning.

  • Roofing structures are usually manufactured from wood.  Excessive moisture in enclosed areas such as attics causes the wood to absorb the moisture, promoting dampness and mold and ultimately rotting the wood, which leads to expensive repair costs.  Roofing vents are designed to keep the enclosed area cool and dry. Adequate ventilation in the attic will ensure you achieve the longest possible lifespan from the roofing material.

Inlet And Exhaust Vents, What Are They?

An inlet vent is a general term for any vent installed in your attic or roof area that allows air to enter these areas. The exhaust vent is any vent that allows the hot, moist, or stale air to escape.

You must install the Inlet and exhaust vents in an attic to ensure a free flow of air into the space and back out. The inlet vent is installed as low as possible on the roof or attic area, while the exhaust vent is installed as high as possible. Installing them at different heights allows the hot air to rise and exit the exhaust vent while allowing fresh air to flow into the inlet vent.

Soffit Vents

A soffit vent sits in the soffit area on the underside of the roof.  The soffit is the board that extends from the fascia board to the house wall, covering the bottom of the roof’s overhang.

attic eave

Soffit vents are available in many designs, but all allow the free flow of air through their grid or slot patterned panel.  Soffit vents are inlet vent that allows fresh air to flow into the roof.   Soffit vents are available in various shapes and materials such as plastic, aluminum, or steel.  Choosing the right one for your home will depend on the soffit area’s design and the required flow.

Soffit vents always work in conjunction with ridge vents or similar exhaust vents, allowing fresh air into the roof through the soffit vent and expelling stale and hot air out of the exhaust vents through the convection principle.  For the ventilation process to work effectively, you must fit an inlet and exhaust vent to the roof.

In older homes, soffit vents are rectangular holes covered with screening placed about eight feet apart in the soffit. In newer homes, the soffit vent is a continuous opening in the soffit covered with perforated vinyl.

Signs of Poor Ventilation

There are key signs to watch out for that can indicate a poorly ventilated roof.

  • Recurrent ice dams.

  • Excessive moisture and humidity in your attic.

  • Wet spots on the ceiling near your attic (can also indicate a roof leak).

  • Cold spots in the upper level of your home.

  • Deteriorating insulation from soaking up excess moisture.

  • Rusty attic fasteners.

  • Damaged or curling shingles.

  • Unusually high energy or heating bills.

  • Visible damage inside your home, like peeling paint or bubbled ceiling.

Roof Venting Basics to Help Improve Your Home

Now that you know a bit of why you need roof ventilation let’s go over more of the basics of how it works, where it’s needed, and how it’s installed.

Airflow, Airflow, Airflow

The main thing to know is that roof venting is about getting proper airflow into the attic space.  We’ve gone over what can happen when you don’t have it, but what happens when you do have it?  Proper airflow means consistent temperatures across your attic and in your home.  It also means your home’s wood beams and structure stay dry and last much longer.

Airflow will also ensure your shingles and roofing materials last as long as they intended, without having to work extra hard to insulate your home.  Lastly, consistent airflow can protect any items or insulation you have in your attic that can get very damaged by trapped moisture.

How Do the Vents Work Together?

Your roof requires both intake vents and exhaust vents to work properly.  The intake vents are most often near the bottom of your roof or attic, with the soffit being the most common place.  Then exhaust vents are started at the top of your roof, either on or near the peak.  How it works is air flows into the air intake vents at the soffit vents, fills the attic space, and helps push out that stale, hot air out the top of your roof.  This nice, even flow is what keeps everything working in tandem together.

Both electrical powered and roof turbines move so they can actually enhance how much air gets sucked out of the attic.  They are more expensive but can work wonders for larger attic spaces.  It’s worth noting that gable vents are a great way to let air in and out but don’t contribute to helping air flow throughout the attic based on their placement and design.

What Do You Need to Ventilate Your Roof?

There are many parts to a roofing ventilation system, and it’s good to know the names of each, so you know what you do or don’t need.  Common ventilation parts include:

  • Continuous soffit vent

  • Turbine vent

  • Gable vent

  • Hood vent

  • Soffit vents

  • Round soffit vents

  • Ridge vent

Important Things to Know Regarding Ventilation

Like your home and roof, a bit of homeowner maintenance is required to keep things running smoothly and prevent any issues.  The same goes for your roof ventilation system.  The following important things to note are vital to keeping your vents clean and in working order.

  • Pairing insulation with ventilation is critical to really seeing cost-savings on bills.  A properly ventilated attic is excellent, but without the insulation to support it, you might not see a big difference in your bills or temperature control inside your home, depending on the situation.  So always make sure your attic is properly insulated as well, especially if insulation was damaged due to excess moisture.

  • Look into your shingles. Venting often shows the most benefit in hot climates where hot air gets trapped in the attic with nowhere to go.  This heat can damage roofing shingles by prolonged exposure to high temperatures and moisture.  Some shingle manufacturers might even void warranties if ventilation standards are not met or cause shingle failure.  So make sure to pair your ventilation with well-installed shingles as well. The roofing system should work as a whole.

  • You should have at least 1 square foot of vent area per 300 square feet of attic floor.  More ventilation is never bad, but this is a general rule of thumb to follow.

  • Your vents can and will get clogged. Things like insulation, dirt, debris, cobwebs, and more can clog up your soffit vents.  When you clean your gutters (which you should also do), you can also clean out your soffit intake vents.  A light pressured air compressor can do the trick; just make sure to wear goggles!

  • If your roof gets damaged from a storm, it’s possible your vents did too.  There are many pieces to your roofing system, from the shingles to the gutters to the flashing, and of course, your vents.  The vents are often made of a light metal which is susceptible to dents and damage from hail.  So if you ever experience a hail storm or extreme weather, make sure to check (or hire a professional) to look for damage on your vents.