Massachusetts Code Requirements for Make-Up Air Units Explained

Understanding Make-Up Air Requirements for Massachusetts Homes

If you’re installing a powerful kitchen range hood in your Massachusetts home—especially one rated over 400 CFM—chances are, you need a make-up air unit to meet state building code. But what exactly is make-up air, and why is it required?

When a high-capacity exhaust fan, like a range hood, pulls air out of your home, it creates negative pressure. That missing air needs to be replaced or “made up” from an outside source. Without it, you could experience poor airflow, uncomfortable drafts, or even backdrafting from gas appliances.

Many Massachusetts homes unintentionally violate local ventilation codes simply by upgrading to a more powerful kitchen hood without updating their make-up air system.

Let’s dive into how to install make-up air for a range hood and avoid common mistakes Massachusetts homeowners often make.

Why Make-Up Air Matters for Kitchen Range Hood Installations

Meeting code is one thing—protecting indoor air quality and comfort is another. A well-installed make-up air unit can solve both problems.

How Make-Up Air Works

Make-up air systems bring in fresh, tempered air to replace what your range hood exhausts. This helps stabilize indoor air pressure and prevents safety and performance issues.

Here’s what they typically include:

• Outdoor air intake duct
• Damper to control flow
• Motorized fan (on some systems)
• Optional heating or tempering element

Massachusetts building code mandates make-up air for vent hoods over 400 CFM. If your hood is that strong, this requirement isn’t optional—it’s a key part of keeping your home both comfortable and compliant.

Benefits of Proper Make-Up Air Installation

Installing the right make-up air system can significantly improve:

• Kitchen comfort: No more drafts from random windows or doors
• Indoor air quality: Reduces smoke and stale odors
• Energy efficiency: Proper airflow supports your HVAC system
• Code compliance: Avoid costly corrections during inspections

According to Mass Save®, proper ventilation in homes with fuel-burning appliances can help prevent carbon monoxide buildup, which is a common safety hazard caused by improper air balance.

How to Install Make-Up Air for Range Hood in Massachusetts

Installing make-up air isn't just about adding a duct—Massachusetts municipalities follow strict codes that require proper equipment sizing, placement, and performance. Here’s what to know if you want to do it right.

Step-by-Step Look at Make-Up Air Unit Installation

Evaluate your existing ventilation  

Start by determining how much air your range hood exhausts, and whether your current home ventilation can compensate.

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Check local building code regulations  

In most cases throughout Massachusetts, range hoods over 400 CFM need a mechanical make-up air system.

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Choose your make-up air unit  

Depending on the hood’s power and home layout, options include motorized dampers, inline fans, or pre-tempered make-up air units. Brands like Mitsubishi Electric or Daikin offer compatible systems if energy efficiency is a priority.

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Position the intake correctly  

The fresh air duct should bring in outdoor air from a clean location, away from driveways, vents, or appliances that might pollute the incoming air.

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Add temperature control  

In Massachusetts winters, untempered air can make your kitchen feel like a freezer. Models with built-in heating coils or integration with your HVAC system offer a better solution.

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Link to your range hood  

The unit must activate automatically whenever your hood turns on. This can be controlled via an interlock system or smart controller.

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Special Considerations for Massachusetts Homes

Cold weather in the Northeast makes tempering outdoor air essential. Uninsulated ducts or vents that release cold air indoors can make your HVAC system work overtime.

Also important:

• Use UL-rated insulated ducts
• Weather-seal exterior intake vents
• Install backdraft dampers to prevent cold air inflow

Now that you know the basic setup, let’s look at when and how a homeowner should seriously consider adding or upgrading their system.

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Top Signs You Need Make-Up Air and What to Do About It

Even if your home passed inspection years ago, a kitchen remodel or appliance upgrade might now put you out of compliance. Watch for these warning signs.

Common Indicators of Poor Air Balance

• Drafts near doors when the hood is on
• Gas appliance burners flicker or blow out
• Smells linger in the kitchen after cooking
• HVAC airflow decreases when the hood runs
• Increased heating or cooling bills

If you notice any of these, your house might be straining to maintain proper air pressure due to your range hood’s high suction.

Simple Fixes vs. Code-Compliant Installation

Small fixes like opening a window can help temporarily—but they’re not a substitute for real make-up air. Massachusetts requires permanent, mechanical solutions when venting over 400 CFM.

Here’s a quick decision guide:

• Under 400 CFM: Likely no make-up air needed (but helpful for comfort)
• 401-600 CFM: Mechanical make-up air required by code
• 601+ CFM: May require tempered or filtered make-up air

Failing to meet code can delay permits during a renovation or even halt final occupancy approvals.

Make-up air systems aren’t just about passing inspection—they’re about protecting your family from backdrafting risks and preserving the investment you made in your remodeled kitchen.

Stay in Control with the Right Equipment

Look for smart interlock systems that sync with your range hood, and make sure controls are easy to access. This ensures you’re always operating safely without relying on memory or guesswork.

Massachusetts homes, with their mix of old construction and airtight modern upgrades, demand careful planning when it comes to ventilation. Make-up air systems provide that balance—and help you enjoy cleaner, safer air with zero drama during your next inspection.

For more guidance on indoor air quality standards, Massachusetts homeowners can review recommendations on the EPA’s ventilation page.

Taking time to understand the Massachusetts code requirements for make-up air units means you’ll protect your home’s comfort, safety, and value. Whether you're updating your kitchen or building new, getting ventilation right from the start is one of the best decisions you can make.