What Causes Carbon Monoxide in a House? A Comprehensive Guide

July 28, 2024

I'll never forget the day my neighbor, Sarah, called me in a panic. Her family had woken up feeling dizzy and nauseous, with pounding headaches. Luckily, they realized something was wrong and got out of the house quickly. It turned out they had a close call with carbon monoxide poisoning due to a blocked chimney. This experience made me realize how important it is for all of us to understand what causes carbon monoxide in our homes.


Carbon monoxide is often called the "silent killer" because it's odorless, colorless, and can be deadly. As someone who's seen firsthand how scary a carbon monoxide incident can be, I want to share what I've learned about its causes and how to prevent it. Whether you're in Maine, New Hampshire, or anywhere else, this guide will help you keep your home safe.

Select Chimney Services

Waterproofing

  • Protection from elements: Shields your chimney from rain, snow, and ice.
  • Preventative maintenance: Helps avoid costly repairs due to water damage.
  • Increased chimney lifespan: Extends the life of your chimney structure.
  • Improved energy efficiency: Reduces heat loss through a damp chimney.

Stainless Steel Liners

  • Fire safety: Provides a non-combustible liner to prevent chimney fires.
  • Improved draft: Enhances the efficiency of your fireplace or wood stove.
  • Durability: Resistant to corrosion and high temperatures.
  • Customizable options: Available in various sizes and lengths to fit your chimney.

Demolition and Tuckpointing

  • Chimney restoration: Repairs damaged or deteriorated chimney structures.
  • Safety: Removes hazardous chimney components.
  • Aesthetics: Improves the appearance of your chimney.
  • Structural integrity: Reinforces the chimney for long-term stability.


Understanding Carbon Monoxide

What is Carbon Monoxide?

Carbon monoxide (CO) is a gas that's produced when fuels like gas, oil, coal, and wood don't burn completely. It's invisible and has no smell, which makes it particularly dangerous. In our homes, it can come from various sources that we use every day.


Why is Carbon Monoxide Dangerous?

The danger of carbon monoxide lies in how it affects our bodies. When we breathe it in, CO binds to our blood cells much more strongly than oxygen does. This means our body can't get the oxygen it needs, which can lead to serious health problems or even death if we're exposed to high levels or for a long time.


Common Sources of Carbon Monoxide in Homes

To keep our homes safe, it's crucial to know where carbon monoxide might come from. Here are the main culprits:


Fuel-Burning Appliances

Furnaces and Boilers

Our heating systems are one of the most common sources of carbon monoxide. If they're not working properly or are poorly ventilated, they can release CO into our homes.


Water Heaters

Just like furnaces, water heaters that use fuel can produce carbon monoxide if they're not functioning correctly.


Stoves and Ovens

Gas stoves and ovens can be a source of CO, especially if we use them improperly, like using a gas oven to heat a room.


Fireplaces and Wood Stoves

There's nothing quite like a cozy fire, but if our chimneys are blocked or our wood stoves aren't properly maintained, they can be a major source of carbon monoxide.


Portable Generators

During power outages, many of us turn to portable generators. But using them indoors or too close to the house can lead to CO buildup.


Vehicles in Attached Garages

Running a car in an attached garage, even with the door open, can allow carbon monoxide to seep into our homes.


The Silent Culprit: Chimney Blockage

As a homeowner in the Northeast, I've learned that chimney blockage is a particularly sneaky cause of carbon monoxide buildup. Let's dive deeper into this issue.


How Chimney Blockage Leads to Carbon Monoxide Buildup

Our chimneys play a crucial role in venting harmful gases, including carbon monoxide, out of our homes. When a chimney becomes blocked, these gases have nowhere to go but back into our living spaces. This blockage can happen gradually, making it easy to overlook until it becomes a serious problem.


Signs of a Blocked Chimney

Recognizing the signs of a blocked chimney can help prevent carbon monoxide buildup. Look out for:

  • Soot or debris falling into the fireplace
  • A strong, unpleasant odor coming from the fireplace
  • Difficulty starting or maintaining a fire
  • Smoke entering the room when a fire is lit


Importance of Regular Chimney Maintenance

Regular chimney maintenance is key to preventing blockages and ensuring proper ventilation. As someone who's dealt with chimney issues, I can't stress enough how important this is. A professional chimney service can identify and address potential problems before they become dangerous.


Preventing Carbon Monoxide in Your Home

Now that we understand the causes, let's talk about prevention. Here are some steps I've taken to keep my family safe:


Regular Appliance Maintenance

I make sure to have all my fuel-burning appliances serviced annually by a qualified technician. This includes my furnace, water heater, and gas stove.


Proper Ventilation

Good ventilation is crucial. I've made sure all my vents are clear and that my home has proper air circulation. This is especially important in areas with fuel-burning appliances.


Installing Carbon Monoxide Detectors

Carbon monoxide detectors are a must-have in every home. I've installed them on every level of my house, including near bedrooms. Remember to test them monthly and replace the batteries as needed.


Professional Chimney Inspections

After learning about the dangers of chimney blockage, I now schedule annual chimney inspections. A professional can spot issues that I might miss and ensure my chimney is safe and efficient.


What to Do If You Suspect Carbon Monoxide Exposure

Knowledge is power, especially when it comes to carbon monoxide safety. Here's what you need to know:


Recognizing the Symptoms

Carbon monoxide poisoning can mimic other illnesses, which makes it tricky to identify. Common symptoms include:

  • Headache
  • Dizziness
  • Nausea
  • Shortness of breath
  • Confusion
  • Blurred vision
  • Loss of consciousness


If multiple people in your household experience these symptoms simultaneously, it could be a sign of carbon monoxide exposure.


Immediate Actions to Take

If you suspect carbon monoxide in your home:

  1. Get everyone out of the house immediately, including pets.
  2. Call emergency services (911) from outside the home.
  3. Don't re-enter the house until emergency responders give you the all-clear.
  4. Seek medical attention, even if symptoms seem mild.


Carbon Monoxide Safety in ME and NH

Living in Maine and New Hampshire, we face unique challenges when it comes to carbon monoxide safety, especially during our long, cold winters.


Local Regulations and Resources

Both Maine and New Hampshire have laws requiring carbon monoxide detectors in residential buildings. It's important to familiarize yourself with these regulations to ensure your home is compliant and safe.

For more information:

  • Maine: Maine State Fire Marshal's Office
  • New Hampshire: NH State Fire Marshal's Office

Finding Trusted Chimney Services in Your Area

Regular chimney maintenance is crucial in our region due to our heavy reliance on heating systems during winter. Finding a trusted chimney service in your area can make all the difference in keeping your home safe from carbon monoxide.


Conclusion

Understanding what causes carbon monoxide in our homes is the first step in preventing this silent danger. From maintaining our appliances to scheduling regular chimney inspections, there are many ways we can protect ourselves and our loved ones.

Remember, carbon monoxide safety isn't a one-time thing—it requires ongoing attention and care. By staying informed and taking proactive steps, we can create safer, healthier homes for ourselves and our families.

If you have any concerns about carbon monoxide in your home, don't hesitate to reach out to a professional. Your safety is worth it!


Key Takeaways

  • Carbon monoxide is a colorless, odorless gas that can be deadly.
  • Common sources include fuel-burning appliances, fireplaces, and blocked chimneys.
  • Regular maintenance of appliances and chimneys is crucial for prevention.
  • Install carbon monoxide detectors on every level of your home.
  • If you suspect carbon monoxide exposure, leave the house immediately and call 911.


FAQs

  1. How often should I have my chimney inspected? I recommend having your chimney inspected annually, preferably before the heating season starts.
  2. Can I use a gas oven to heat my home? No, using a gas oven for heating can lead to dangerous carbon monoxide buildup. Always use proper heating appliances.
  3. Where should I place carbon monoxide detectors? Install detectors on every level of your home, especially near sleeping areas.
  4. How long does carbon monoxide poisoning take? It depends on the concentration of CO and exposure time. Symptoms can appear within minutes or hours.
  5. Can carbon monoxide travel through walls? Yes, CO can seep through drywall and small cracks, which is why proper ventilation is crucial.
  6. Is it safe to use a portable generator during a power outage? Only if used outdoors, far away from windows, doors, and vents. Never use generators indoors or in partially enclosed spaces.
  7. How can I tell if my chimney is blocked? Signs include difficulty starting fires, smoke entering the room, and soot buildup. When in doubt, contact a professional for an inspection.


Remember, when it comes to carbon monoxide safety, it's always better to be cautious. If you have any doubts or concerns, don't hesitate to reach out to a professional or learn more about chimney services. Your safety is the top priority!

Defending Your Masonry: The Case for Stainless Steel Liners in Portland

By John Constantine • May 20, 2026
Every winter in Portland brings extreme temperature drops, biting winds, and heavy snowfall. Homeowners rely heavily on their heating systems and fireplaces to keep their living spaces comfortable. However, a frequently ignored component of household safety hides right inside the brickwork of your property. Your flue requires absolute structural integrity to safely vent toxic gases and extreme heat outdoors. When older clay tiles begin to crack, your property is immediately exposed to severe fire risks and hazardous gas leaks. At Burleson A.T. Electric , we specialize in modernizing aging venting systems with high-grade metal alloys designed to protect your home and your family. The Hidden Dangers of an Unlined Flue Many older homes across Maine were built using traditional clay tiles to line the inside of the flue. Clay is a rigid, porous material that absorbs condensation and atmospheric moisture over time. When subjected to the rapid heating and cooling cycles of regular fireplace or furnace use, these tiles inevitably crack, shift, or crumble. This degradation process leaves combustible structural materials in your attic and walls exposed to stray sparks and intense heat. We recently discussed how neglecting routine maintenance puts Portland homes at risk every winter . The structural breakdown of an unlined or failing flue ranks among the most critical safety hazards a property owner can face. Recognizing the warning signs early can save you from catastrophic damage. Watch for these specific indicators of clay tile failure: Visible crumbling flakes of clay accumulating in your firebox. Water stains on the interior walls adjacent to the masonry. Drafting issues causing smoke to back up into the room. Foul, acidic odors radiating from the hearth during humid days. How Stainless Steel Liners Outperform Traditional Clay Replacing deteriorated clay with stainless steel liners provides an immediate and permanent upgrade to your venting system. These flexible or rigid metal tubes run the entire length of the flue. They create a seamless, airtight corridor for smoke, carbon monoxide, and creosote to exit your home safely.

This One Oversight Is Putting Portland Homes at Risk Every Winter

By John Constantine • May 17, 2026
Portland, Maine is known for its picturesque winters, but the northern climate is brutal on historic and single-family homes. Homeowners frequently focus their seasonal preparation on insulating pipes, sealing drafty windows, and servicing the central heating furnace before November arrives. Yet, thousands of local property owners completely bypass the very structure venting the toxic gases from their heating systems. Leaving your masonry uninspected and exposed to the elements is a massive vulnerability. By the time structural deterioration or an active chimney fire becomes obvious, the underlying damage is already severe and incredibly expensive to correct.

Protecting Your Portland Home with Professional Gutter Cleaning and Repair

By John Constantine • May 13, 2026
Living in Portland, Maine brings beautiful coastal views but also guarantees exposure to brutal weather conditions. Heavy seasonal rain, relentless winter snow, and accumulating autumn leaves all take a serious toll on your property. Your home relies on a properly functioning exterior drainage system to direct water safely away from the foundation and roofline. When debris clogs that system, water simply finds another destructive path down.  At Select Chimney , we see firsthand how neglected maintenance leads to extensive structural decay. Protecting a property requires a holistic approach to exterior care. By managing water flow properly, you preserve everything from your roof deck to your basement walls. Routine attention to your home exterior prevents minor seasonal buildup from turning into a massive restoration project later down the road.

Why Older Portland Homes Require Immediate Chimney Repairs

By John Constantine • May 11, 2026
Walking down the tree-lined streets of the West End or driving through Deering Center reveals a defining characteristic of Portland, Maine. The historic architecture is undeniably stunning. However, a closer examination of the rooflines on these century-old homes tells a story of structural fatigue. Brick columns are noticeably leaning. Mortar joints are dissolving into fine powder. Homeowners across Cumberland County are reporting a sudden and significant increase in masonry deterioration. This localized trend is not a coincidence. It is the cumulative result of time, harsh coastal weather patterns, and outdated building materials reaching their physical limits. Homeowners who purchased properties built in the 19th and mid-20th centuries are now inheriting decades of hidden wear and tear. Recognizing the environmental and structural factors behind this decay is the first step in protecting your property.

Protecting Your Portland Home with Professional Chimney Waterproofing

By John Constantine • May 5, 2026
Living in Portland, Maine, means navigating incredibly unpredictable and intense weather patterns. Residents experience everything from relentless spring rain and coastal storms to deep winter freezes. While you might focus on fortifying your roof or upgrading your windows, the most vulnerable structural element is often standing right above you. Unprotected masonry absorbs moisture rapidly. At Select Chimney , we see the resulting damage firsthand across local neighborhoods. Waterproofing is an essential defense mechanism for any masonry structure exposed to the harsh elements of New England. Why Masonry Fails in Coastal Maine Brick and mortar are naturally porous materials. They act like rigid, heavy sponges. When driving rain hits the side of your house, untreated masonry drinks it in through a process known as capillary action. We covered the early stages of this deterioration in our post detailing how most chimney problems start in Portland homes without warning . As water settles into the microscopic voids within the brickwork, it creates a ticking clock for structural failure. This is especially true for the historic homes scattered throughout Portland, where older, softer bricks were often used during the original construction. Without a protective barrier, these materials are left completely defenseless against the coastal humidity and precipitation.

How Most Chimney Problems Start in Portland Homes Without Warning

By John Constantine • May 1, 2026
Many homeowners do not think about their heating systems until the first bitter evening of the season. You turn on the heating system, light a fire, and expect everything to work flawlessly. However, the structures venting those fires often deteriorate entirely out of sight. A masonry stack might look perfectly sturdy from the street while hiding severe structural deficits inside the flue or right beneath the roofline. Portland, Maine presents a particularly harsh environment for exterior masonry. Historic properties and newer builds alike face relentless exposure to coastal winds, heavy snowfall, and driving rain. These elements wage a silent war against brick and mortar. The damage rarely announces itself with a sudden collapse. Instead, it begins with microscopic vulnerabilities that gradually compromise the safety of your home. Understanding how these hidden issues develop is the first step toward protecting your property value and your family. Relying on preventative maintenance from professionals like Select Chimney Service ensures you catch these quiet threats before they mandate catastrophic repair bills.

Preserving Your Property: A Guide to Chimney Demolition and Tuckpointing in Portland ME

By John Constantine • May 1, 2026
The harsh weather of Maine is notoriously unforgiving on exterior masonry. Constant shifts from freezing rain to sub-zero temperatures create immense stress on the brick and mortar outside your home. Water naturally penetrates porous surfaces over time. When that trapped moisture freezes, it expands and forces the masonry apart. Over decades, this continuous cycle degrades even the strongest materials. Homeowners must address these structural vulnerabilities before they cause severe water damage or structural collapse. Managing these specific masonry failures requires an experienced eye and careful craftsmanship. The professionals at Select Chimney understand exactly how the coastal New England climate impacts local architecture and what it takes to permanently correct the damage. Identifying Severe Masonry Decay Knowing when to call a professional requires an understanding of what failing masonry looks like. Many homeowners only notice a problem when water begins leaking into their attic or living room ceiling. By the time water breaches the interior of the home, the exterior structure has likely been compromised for years. There are several highly visible warning signs that indicate your mortar joints are failing. Look for the following indicators when inspecting your property from the ground: Spalling Bricks: This occurs when the face of the brick flakes off, crumbles, or completely pops out of the structure. It is a direct result of moisture freezing inside the brick itself. Deteriorating Mortar: Healthy mortar should be solid and flush with the brickwork. If you see gaps, deep recesses, or piles of sandy debris resting on your roof shingles, the mortar has lost its bonding strength. Efflorescence: A powdery white stain on the exterior of the brickwork indicates that water is moving through the masonry and leaving salt deposits behind on the surface. Visible Leaning: A structure that leans or tilts is a severe safety hazard. This indicates that the structural integrity has completely failed on at least one side.

Why More Portland Homeowners Are Booking Annual Chimney Cleaning Early

By John Constantine • April 24, 2026
The arrival of crisp autumn air in Portland, Maine usually signals the start of intense preparations for the winter months. Historically, property owners waited until the first frost to consider the state of their heating systems. However, a significant behavioral shift is occurring across local neighborhoods. Homeowners are increasingly scheduling their annual sweeps and inspections during the spring and summer.  This proactive approach to property maintenance is driven by a combination of severe local weather patterns, financial foresight, and a deeper understanding of home safety. By choosing to act months ahead of the traditional autumn rush, residents are securing better availability, preventing extensive weather-related damage, and ensuring their heating systems operate safely when the harsh New England winter finally arrives. Working with a dedicated local provider like Select Chimney Service during the off-season offers distinct advantages. Instead of competing for limited appointments in October, early planners guarantee their homes are safe and compliant long before the first log is lit.

Defending Your Home Against Moisture: A Guide to Chimney Waterproofing in Portland

By John Constantine • April 22, 2026
Portland, Maine, brings demanding weather conditions to New England homeowners. Coastal rainstorms, heavy winter snowfall, and intense freezing temperatures constantly batter the exterior of your property. Your chimney sits entirely exposed above the roofline, facing the brunt of every passing storm. Masonry materials like brick, mortar, block, and stone are highly porous. They act very much like rigid sponges that absorb environmental moisture rapidly. When left unprotected, this constant water intrusion inevitably leads to structural decay. The team at Select Chimney Services understands exactly how these specific local weather patterns threaten your masonry. We focus entirely on preserving the safety, functionality, and structural integrity of your home heating systems. The Impact of the Portland Climate on Masonry Understanding the relationship between Maine weather and masonry requires looking closely at the freeze-thaw cycle. During a standard winter, water easily penetrates the porous surface of unprotected bricks. When the temperature drops below freezing overnight, that trapped water turns into ice. Water expands by roughly nine percent when it freezes. This expansion creates immense microscopic pressure inside the brick itself. Over multiple seasons of freezing and thawing, this pressure causes the face of the brick to crack, flake, and eventually break off completely. This process is known as spalling. Securing a reliable defense against this destructive cycle starts by partnering with the right professionals. Select Chimney Services provides the expertise necessary to evaluate, repair, and protect your home from devastating moisture intrusion. Identifying Moisture Damage Before It Spreads Water damage rarely remains hidden for long. It leaves several clear physical indicators on both the interior and exterior of your property. Catching these signs early is crucial for preventing massive structural failures.

Annual Chimney Sweep or Inspection in Portland, Maine: Which One Comes First?

By John Constantine • April 18, 2026
Portland, Maine experiences long, freezing winters that demand reliable home heating. Many homeowners rely on wood stoves and traditional fireplaces to keep their families warm throughout the darkest months of the year. With constant use comes the inevitable accumulation of soot and creosote inside the flue. When preparing your heating system for the harsh New England winter, a common question arises regarding maintenance order. Do you need a cleaning first, or should a professional evaluate the structure before any brushing begins? Understanding the precise distinction between these two critical services helps preserve your property value and prevents dangerous flue fires. Properly sequencing your maintenance ensures your home remains a safe haven against the cold.