Air Sealing 101: A Complete Guide on Sealing Your Home for Comfort

Indoor Air Quality, Saving Energy

Air leaks are like a plague to a cozy home. They take away your well-deserved comfort, they compromise your family’s health and safety, and it burns through your resources and savings because it consumes a lot of energy. How can you beat air leaks?

Air sealing is the answer. What are the benefits of sealing air in your home? How can you effectively perform home air sealing in a way that would yield the expected advantages? Are there dangers in overdoing it?

Learn the answers to these questions as you continue reading. 

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How Do You Air Seal Your Home Like a Pro?

Air sealing is indispensable to achieving optimum home comfort. This is a required step before you can attain adequate insulation and effective moisture control. If sealing is done right, it can also generate energy savings on gas or electrical consumption by your HVAC system.

However, if done poorly, air sealing can be excessively over-the-top it defeats the purpose. It may even cause your family sudden health concerns and discomforts.

So how do you prevent air sealing from becoming detrimental to your comfort and well-being?

Here is a complete guide to performing air sealing just the right way, backed by the Department of Energy and other reliable sources

  1. Perform an energy audit or assessment. – An energy audit is performed by a professional assessor who inspects and analyzes the specific flow of energy in a certain home. These trained men utilize tools and formulas in surveying how much energy is being used in a residence and whether there are energy-wasting issues that need to be resolved. Energy assessors will then make recommendations to the homeowner to save more energy by air sealing and insulation. 

The benefit of having a professional do your energy audit is to avoid guesswork that would lead to either inadequate or overdoing airtightness.

  1. Adhere to the standard air exchanges required for your home. – Once, the assessor has finished with his evaluation, he will inform you of the required number of air exchanges your home needs per hour. This will allow your living areas to “breathe” so to speak, so no leakages can ruin the energy efficiency of your home, but at the same time, the indoor air is not stale nor too restricted. 

Each home is different and so is its need for air exchanges. It is crucial that you follow the mandatory “0.35 air changes per hour but not less than 15 cubic feet of air per minute (cfm) per person. as the minimum ventilation rates in residential buildings,” according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers or ASHRAE. 

  1. Conduct a “blower door” test. – This airtightness test is executed through the use of a variable-speed type of fan installed directly to the frame of your exterior door. It is equipped with a pressure gauge and an airflow manometer. 

The main purpose of this test is to detect any air leaks that need to be sealed around your home. The giant fan will suck out all the indoor air. This would allow outdoor air to attempt to come through any unplanned openings. The energy auditor would then be able to search for the air leakages around the house with the use of a smoke pencil.

  1. Apply caulking and weatherstripping. – Once the unwanted holes, gaps, and crevices are identified and located, air sealing measures can now be applied. 

Caulking is used for openings that are narrow and generally stationary. These include unmoving gaps in the windows and doors, bathtubs, plumbing, vents, and electrical wiring that runs through the house. Use a special kind of fire or heat-resistant caulk for furnaces, chimneys, and gas-powered water heater vents. 

Weatherstripping with pliable sealing gaskets is more suited for moving parts of the house such as the bottom of doors, opening sides of windows, hatches, and attic air sealing.

  1. Put mechanical ventilation in place. – This is the critical step to reducing the chance of backdrafting in your home and its troublesome effects. As soon as you air seal your home properly, it still requires fresh air to be brought in. Mechanical ventilation invites fresh air, distributes it evenly to various spaces indoors, and facilitates air exchanges that your house requires. 

You can choose from a variety of mechanical ventilation options available in the market. Just make sure that you consider your local climate before deciding whether to employ Supply Ventilation, Exhaust Ventilation, or Balanced Ventilation Systems.

The Essence of Air Sealing

Air sealing is the most direct and effective approach to air infiltration. Unplanned holes, gaps, and openings around the house let outside air in uncontrollably and allow inside processed air to escape. 

One of the most silent but detrimental enemies of home comfort is an air leak. Air leaks, sometimes dubbed air infiltration, come in various forms: small holes, tiny cracks, and openings around the doorways or window hinges. 

They allow outside air into the house, whether it is cold or hot air, and invade your conditioned space. Obviously, these unwanted openings also let the heated and cooled air from the inside escape.

Cold drafts and hot spots are the primary determinants if there are leaks around your house. Unplanned holes, cracks, and crevices let cold air in from the outside and let out heated air from inside during winter. In the summer, air-conditioned air can escape the confines of your living space and warm air can infiltrate through unwanted openings.

Some people simply ignore these gaps as they think they are good ways to naturally ventilate their living spaces.

They are utterly and terribly WRONG.

If you want a comfortable and energy-efficient home where heating and cooling systems thrive and provide your desired temperature year-round, you should see air leaks as your nemesis.

The Rewards of Home Air Sealing

Air sealing is an essential home improvement alongside insulation, ventilation, and moisture control. If done well, it makes your home more energy efficient, your HVAC systems and home structure more durable and require fewer repairs, and contributes to the overall indoor air quality of your abode.

Let us explore in detail the three advantages of properly air sealing your home:

Energy Efficiency

The process of air sealing may cost you upfront expenses such as air sealing materials, assessment from a professional energy assessor, and labor fees. But these charges would not be as significant if you compare them to your savings if you air seal your home right.

As it is, your air conditioner consumes at least 70% of your electricity bill. The process to turn your hot stale air indoors into a cool dry breeze is complex and requires much energy. This goes the same for your furnace that works hard to keep the inside of your home warm and cozy.

These elegant cooling and heating processes get detracted by air leaks. They viciously let out the chilled or heated air and give entrance to unprocessed air from outside.

If you neglect the leaks around your house, you are willingly wasting 20% to 30% of those precious energies. You are literally spending money without the comfort you paid for. You are also subjecting your AC and furnace to daily struggle which may need early repair calls. 

Lasting HVAC Systems and Home Structure

It is no secret that air conditioners and furnaces thrive in airtight spaces. The simple reason behind this is that these temperature-altering devices draw in the existing air from your home, process it either by cooling or heating the air, and blow back the processed air to the rooms.

Air leakages present a problem when they let the manufactured air out. The cold air will continue to escape making the AC work harder to lower the temperature. The same will happen to a furnace where the heated air will keep on evading the space, so your heating system will keep on running yet never meet your desired thermostat setting.

This can lead to overuse and overheating which inevitably leads to unnecessary repairs. They may even cause your HVAC systems to prematurely retire and require an early replacement. What a waste!

Neglected air leakage will also create additional issues with the integrity of your home’s structure. Moisture can seep through your walls, foundation, and ceiling and weaken the durability of your house. 

If you want to be spared from expensive home and appliance repairs, prioritize sealing unwanted holes and openings in your home improvements bucket list.  

Improved Indoor Air Quality

Making your home as airtight as possible saves you from allergens, airborne toxins, and other pollutants that can invade your breathing space. Dirt, dust, pollen, dander, chemicals, and other minute particles can induce allergies, asthma, and other respiratory issues.

If there are leaks present in your home, the HVAC system cannot maintain the right level of humidity indoors. This scenario would lead to inconsistent temperatures in various rooms like the attic, basement, and bathroom. Persistent condensation on surfaces encourages mold growth indoors.

Molds can come through openings around your house and neglected leakages. Mold problems are not just eyesores and foul-smelling. People who are sensitive to mold can present with irritating symptoms similar to an allergy attack: itchy eyes, reddish skin, sneezing, wheezing, and coughing. 

If you have family members who have severe allergies and chronic lung and breathing conditions and are immunocompromised, they are more susceptible to fungal sickness.

Air sealing these pesky leaks will save you from these costly health problems.

The Precise Way to Air Seal

Proper and adequate air sealing does not just mean hastily covering all holes and openings you catch sight of in your house. The process includes advanced planning, careful testing, and wise execution.

Feel the Drafts

Your first clue on the presence of air leaks is how you feel inside a room or a space. During cold and windy weather, a chilling waft of cool air can suddenly hit you even as you sit in a room with closed doors and shut windows. Or in the scorching summer heat, you seek the refuge of your air-conditioned home only to find yourself sweaty and clammy due to the hot spots in certain areas of the house.

Don’t be quick to blame it on your HVAC systems!

Air conditioners and furnaces are designed to measure the temperature in an enclosed space and cool it down or warm it up depending on your pre-set level in the thermostat. But air leaks are sneaky little troublemakers that let out the processed air to evade your space while welcoming the unconditioned air, making it hard for your devices to keep the comfort level constant.

Infiltration of outside air is not just deterrent to a snuggly indoor climate, but it also poses potential health risks as it permits airborne pollutants without you detecting them. Dust, pollen, dander, small insects, and even smoke could gain access to your breathing space because of these pesky leaks.

Mayo Clinic outlined the potential allergy triggers in the home and air and water leaks are some of the most common problems that a homeowner should address. Leaks cause cold drafts and hot spots which in turn mess up the relative humidity indoors and later encourage molds to develop.

There is indeed an urgent need to tackle these annoying air leaks up to the very last bit of them! But where would you start? 

Test How Tight

As to any opponent, you have to get the lay of the land so to speak by visually inspecting every nook and cranny of your abode where air leaks might be found.

One key thing to remember is about your house’s so-called “envelope”—the exterior of a building or residence composed of the roofing, subfloor, exterior doors, windows, and exterior walls.

Envelopes are classified into two: loose or tight. Loose envelope applies more to warmer climates, where uncontrolled air can be a natural source of ventilation as flows freely through the structure. While places with colder environments are suited to have tight building envelopes so air temperature can be controlled and maintained.

For areas with varied climates, it is advisable to choose a tight envelope rather than a loose one to better control the temperature indoors. 

For this discussion, we will be focusing on tightening up the envelope of your home. 

Start with the exterior of the house, focusing on areas where two different structures meet together like in the corners, siding and chimneys, foundation and exterior brick or siding, and also outdoor faucets.

When you get to the interior, direct your attention to and around electrical outlets, switch plates, and sections where cable TV, phone lines, electricity, or gas services enter your residence. The most obvious places to look are on every side of doors leading outside, windows, attic hatches, vents, and fans.

You can take it to the next level with the use of a flashlight and the help of a partner indoors. Shine a light on your house’s envelope, specifically on suspected areas with gaps, on a dark evening, and turn off all lights inside. Big and gaping cracks will be revealed by this test.

Another practical test you can do is the building pressurization test where you depressurize your home with the use of a large or (even better) industrial fan to suck out all the air from your living space. This is after you close all your windows and doors and turn off all appliances that blow air out. Hold an incense on potential problem sections and see if the smoke flickers. If it does, you have an air leakage around that area.

If you think you can part with an average of $300 to $400 just to make sure that your home is airtight and to increase your family’s comfort, the most reliable test is called the “blower door” test. Instead of a regular fan, it utilizes a variable-speed fan, a frame that fits right into your exterior door, a pressure gauge, and an airflow manometer.

Blower doors can be categorized into two: uncalibrated and calibrated. Uncalibrated doors are effective only in locating air leaks around the house. Calibrated blower doors can give you a more detailed description and measurement of how airtight your home is. It can also tell you if your existing air sealing methods are efficient or lacking.

Once you have isolated the areas with air leakage issues, what now? 

Combat with Caulk

The most popular way of air sealing because of its simplicity and efficiency is caulking. Caulk is a waterproof and flexible compound used to cover and seal cracks, holes, and undesirable openings in your house’s envelope. It can either be made with silicone, polyurethane, latex, or elastomeric.

Deciding which type of caulk you will use for your home would depend on your needed strength of material for the project, its level of adhesion, or its price per cartridge.

Once again, the Department of Energy provided a detailed list of the most common caulking compounds so you can choose which is the most suitable for a particular area in your house.

For example, silicone compounds are best suited for air sealing the bathrooms and kitchen joints as they are more flexible than most types of compounds and have little to no shrinkage.

Meanwhile, latex is effortless to use, water-resistant as soon as it dried, and can be sanded or painted so it is recommended to fill cracks in your tile, plaster, glass, or plastic.

The authority on regulating energy efficiency also has useful tips for a successful caulking job:

  1. Pick a dry day to do your caulking with an ideal outdoor temperature of above 45°F or 7.2°C to prevent moisture from the holes and openings. 
  2. Before caulking, clean and wipe dry the section you will caulk to avoid sealing in moisture and ugly bulks after application. It will also help the adhesion to last longer.
  3. Keep your caulk gun at a 45°angle so the compound can penetrate the crack more deeply.
  4. Do not keep stopping or starting but try to apply the caulk in one continuous stream, only stopping at the bottom of an opening to avert bubbles.
  5. Use a caulk gun with an automatic release to avoid putting too much compound into one spot. Otherwise, release the trigger before pulling the caulk gun from the crack.

These tips only apply to the stationary sections of the house. But what about home components that are constantly in motion like the door, operable windows, and attic hatches?

Weather the Cold by Weatherstripping

Weatherstripping is the answer! Unlike caulk that needs curing, weatherstrips are made of rubber, felt, open-cell foam, vinyl, or metal.

In picking the appropriate type of material to use for weatherstripping a particular part of the house, you should consider its location and the natural wear and tear it would experience in years of use.

The DOE once again offers an array of weatherstripping materials you can choose from, comparing its costs, benefits of using, and its flaws.

Installation of weatherstrips may be easy-peasy to some, but here are some guidelines for quick yet effective air sealing doors and windows:

  1. Clean and wipe dry the surfaces before weatherstripping. The temperature should not go below 20°F or -7° C.
  2. Measure it twice, and cut it once.
  3. Use one continuous strip for each side as much as possible.
  4. The weatherstrip should be snug enough but it should not be a hindrance when opening or closing the window or door.

Can There Be Too Much Home Air Sealing?

But what if you recognize the value of air sealing your home that you may have done it a little bit too much? You worked hard to seal your living space from any air infiltration. However, you started to experience health problems such as tension headaches, unexplained weariness, and difficulty in breathing. 

Could you have air sealed your house a bit much? You may be facing backdrafting problems.

Inside your home are gas-powered appliances such as the furnace, stove, oven, water heaters, and laundry dryer. These devices release waste gases called exhaust fumes that need to be discharged from the house through a flue, duct, or chimney.

It is extremely dangerous if these fumes get sucked back inside your breathing space. This happens when the indoor pressure becomes too low because the inside air is being pushed out consistently by fans yet because of extreme airtightness, no exchange of air is occurring.

Carbon monoxide is one of the most hazardous gases that can be confined inside your home as a result of backdrafting. This poisonous gas can enter your bloodstream and takes the place of oxygen in the red blood cells and cause major injury to your tissues and can be fatal.

A series of unpleasant symptoms will follow because of carbon monoxide poisoning: headache, weakness, nausea, vomiting, shortness of breath, confusion, blurred vision, and loss of consciousness. 

If left untreated or a person has been exposed to massive amounts for a prolonged period, suffocation from carbon monoxide can lead to brain damage or death.

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