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Do You Need Roof Vents with Spray Foam Insulation? (Explained)

Spray foam insulation helps you to get rid of cracks and gaps in your apartment building and office building. It is effective in fighting against air infiltration and manages heat transfer well. Today, we are going to discuss whether one needs roof vents with spray foam insulation or not.

Do you need roof vents with spray foam insulation?

Sometimes roof vents are needed with spray foam insulation. But most of the time, one does not need roof vents with spray foam insulation as it has the ability to make the roof completely airtight. This airtight ability of spray foam insulation removes the need for any roof vent.

Let’s look at different kinds of roof vents and discuss whether you need them with spray foam insulation.

Ridge vents:

Ridge vents are one of the most popular ventilation systems in roofing systems. The ridge vent is designed in a unique way to maintain airflow out of your attic effectively. Ridge vents are popular for regulating airflow on top of the roof and also under the roof.

Ridge vents can also bring unwanted air out of your home. The ridge vents keep the attic of your home dry by controlling the moisture level. Otherwise, the attic area would start to rot by growing mold.

On the other hand, spray foam insulation is used to seal the deck of the roof. It is also effective in terms of regulating the temperature of your roof. One of the benefits of using spray foam insulation is that it can be applied in typically unreachable areas too. 

Further, it also betters the soundproofing ability of your roof.

There are actually two types of spray foam insulation. One is known as the closed-cell spray foam insulation and the other one is known as the open-cell spray foam insulation. You are going to need roof vents if you intend to use closed cell spray foam insulation. 

But when it comes to open-cell spray foam insulation, there is no need for roof vents.

As closed cell spray foam insulation works as an opponent to moisture, your roof will require ridge vents to help it from developing condensation. On the other hand, open-cell spray foam insulation does not work as a barrier to moisture. 

That is why ridge vents will not be needed when you apply open-cell spray foam insulation.

Soffit vents:

Soffit vents are required for healthy air circulation through your roof and home. The soffit vents often pair up with ridge vents to regulate the airflow through the roof deck. Soffit vents also prevent moisture from building up and keep your roof free from mold.

Just like ridge vents, if you are planning to use closed cell spray foam insulation, you are going to need soffit vents on your roof. But soffit vents will not be needed if you are using open-cell spray foam insulation.

Do you need attic ventilation with spray foam insulation?

Spray foam insulation helps you keep your attic airtight. There are actually two kinds of spray foam insulation. The closed-cell spray foam insulation requires you to have attic ventilation. But using open-cell spray foam insulation does not require your attic to have ventilation.

Closed-cell spray foam insulation creates several pockets of gas that can decrease the speed of heat movement through it. That is why this insulation style needs attic ventilation. But open-cell spray foam insulation systems do not need any attic ventilation.

Some might argue that attic ventilation is not needed in any insulation system. This argument comes from the fact that the purpose of spray foam insulation is to make your attic airtight by keeping it sealed. 

It means the temperature of the attic will not be affected by the outside airflow. So if you have managed to apply spray foam insulation correctly, you will not need attic ventilation in any system.

Does spray insulation remove the need for roof ventilation?

The purpose of spray foam insulation is to keep your roof and attic airtight. It means the thick layer of spray foam insulation prevents the outside air from flowing into your attic. It also keeps the air of the attic from flowing outside. 

But the important thing here is that the spray foam insulation has to be applied correctly. Otherwise, the spray foam insulation will fail to keep the attic and room airtight.

Closed-cell spray foam insulation and open-cell spray foam insulation are both rigid and proven performers. Open-cell spray foam insulation possesses an R-value of about four per inch. On the other hand, closed-cell spray foam insulation has an R-value of about six and a half per inch. 

This is why spray foam insulation removes the need for roof ventilation.

3reasons why you do not need vents with spray foam insulation

There are several reasons why you do not need vents with spray foam insulation. Let’s discuss them in detail.

The purpose of the insulation:

The purpose of spray foam insulation is to keep your roof and attic airtight by sealing them. The outside airflow will not be able to penetrate an attic that has been sealed by spray foam insulation. It also keeps the airflow of the attic from leaking outside.

The two layers (outside and inside) never meet and this keeps the temperature of the house at optimum level. That is why there is no need for vents with spray foam insulation.

The purpose of the vent:

The main purpose of the vent is to maintain the flow of air through your attic and roof. It helps your attic to get rid of moisture by monitoring the airflow through it. It saves the roof and attic from developing mold.

But when you use spray foam insulation on the underside of your attic, there is no need for vents as spray foam insulation does the job of maintaining the health of your attic. 

As the purpose of vents and spray foam insulation is the same, only one of them can be used separately.

Versatility of insulation:

Spray foam insulation is quite versatile compared to ventilation. It is able to keep the outside airflow and the inside airflow separate. That is why the house temperature feels less warm in summer and less cold in winter. 

Using spray foam insulation is better for your attic than a ventilation system.

Can spray foam rot your roof?

Spray foam can not technically rot your roof. Rather it saves your roof from rotting by keeping it airtight. Applying spray foam insulation is a difficult task. An inaccurate application of spray foam insulation can create mold inside the layer under the roof. 

If too much or too little spray foam has been laid down on a particular space, it can create pockets of gas.

These pockets of gas and air will create mold inside the thick layer of spray foam insulation. It is better to apply spray foam insulation with the help of a professional even if it costs more. A thoroughly done spray foam insulation process will keep your roof healthy for a long time.

How to vent a spray foam attic?

Venting a spray foam attic involves several steps. Let’s discuss them in detail.

Choosing ventilation system:

An airtight spray foam attic does not have any natural vent inside it. That is why mechanical ventilation has to be introduced to ventilate the spray foam attic. Mechanical ventilation can be done by using ducts and fans. 

It will save the spray foam attic from developing mold by removing moisture from inside it.

Mechanical ventilation can do wonders for your attic. A completely sealed attic might start breaking from inside. Mechanical ventilation will ensure that does not happen. Natural ventilation is not enough in this case.

Implementing the process:

There are different types of mechanical vents that can be used in the attic. For example, ridge vents, soffit vents, and gable vents. If we are talking about a spray foam attic floor, then a ventilation system has to be installed before you apply the spray foam insulation. 

But in the case of a spray foam attic rafter, there is no need for ventilation.

The ridge vents and soffit vents need to be installed together as they coordinate to diminish the moisture and mold away from your attic. Some ventilation fans might fasten the ventilation process along with these vents.

Final Thoughts

Spray foam insulation makes the roof so airtight that roof vents are not needed. But some recommend that roof vents must be used to keep the roof free from any mold and internal damage. Mechanical ventilation can be applied as a precaution against mold and moisture.