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Indoor Air Quality (IAQ)

Remodeling Your Home? Have You Considered Indoor Air Quality?

Use the tabs on the right or click on the area of the house where you plan to remodel.

Adding an AdditionConverting or remodeling a BasementRemodeling a BathroomRemodeling a KitchenRemodeling an AtticVentilationConverting or remodeling a Basement or crawlspace

Basement Conversions or Remodels


Moisture Control Issues

Before beginning any conversion of basement space into living space, check the basement for leaks or other signs of moisture problems. Because damp basements promote biological growth, including molds, they are not healthy places to live in. Thus, any moisture problems should be corrected before you proceed.

Correcting moisture problems may be as simple as redirecting downspout runoff away from the foundation. It may involve re-grading the ground around the house so that it slopes down away from foundation, or venting the dryer to the outside (something that should be done in all homes). Sometimes, however, there are more extensive problems which can be expensive to correct. In any event, the problems should be addressed before you begin other work.


Radon

You should test your home for radon.

Because EPA recommends testing for radon on the lowest lived-in level of a home, even if you've previously tested, if you have not tested in the basement, you should test again. Because fixing a radon problem will usually be easier and less expensive before the basement is finished, you should test before you begin your remodeling project.

See Radon for more information


Ventilation

Good ventilation protects both your health and your home. The basement should be included in your home's ventilation strategy. If your home currently has no mechanical ventilation this may be an opportunity to install a system.


Combustion Appliances

General recommendation for combustion safety should be followed. Because you are changing the basement and affecting how air moves in the home, you should have a professional check how any combustion equipment, pre-existing as well as new, operates after you have finished work in the basement to make sure that it isn't backdrafting.


Flooring

Flooring must not only be resistant to harm by water, but should also prevent water which does get on the floor from penetrating to the area immediately below the surface (e.g., the padding beneath a carpet) where it can be difficult to dry and can lead to mold problems or cause damage.

Do not install carpet near water sources or areas where there is a chronic moisture problem such as around sinks, tubs, showers and toilets. Basements may require special attention in this regard. There are two potential problems with installing carpet on a concrete slab. The first is the possibility that water in the form of liquid water and/or water vapor will come up through the slab, causing chronic dampness in the carpet leading to mold growth. This problem is not unique to carpets, and it highlights the need to address moisture up front.

The second is that concrete slabs, especially those without insulation underneath, are often colder than the air in the basement. In fact this is a situation which may be more likely with carpet which insulates the slab making it even colder. In this situation, moisture in the air can condense on the cooler slab, exposing the carpet to moisture and promoting mold growth.


Windows

Basement remodeling may present a good opportunity to replace old windows with new ENERGY STAR® windows. While costs do not always justify the change from purely an energy savings perspective, there may be other benefits of new windows. More efficient windows may be less prone to condensation and related mold growth. Painted window sashes and frames in homes built before 1978 may contain lead-based paint; this is a special concern because the friction of opening and closing windows can release lead dust into the home.


General Recommendations

You should also review the general recommendations for all remodeling and renovation projects in the guidance "Addressing Indoor Environmental Concerns During Remodeling."

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Bathroom Remodel

Ventilation

Good ventilation protects both your health and your home. Ventilation is especially important in bathrooms to remove unwanted moisture. This helps prevent the growth of mold and mildew, which can cause allergic reactions and aggravate lung diseases such as asthma. During renovation, be sure to check that your bathroom fan is functioning properly. This means not only that the motor makes noise or that the fan is running; it needs to be exhausting a sufficient amount of air*. And the air should be exhausted directly to the outside, and not just into an attic or some other space in the house.

If you do not have a bathroom exhaust fan or if your current fan is not working, you should install one.

ENERGY STAR® has finalized the ventilation fan specification.

In cold climates, bathroom exhaust fans can be used as part of a strategy to provide ventilation for the whole house. See the U.S. Dept. of Energy's Energy, Efficiency & Renewable Energy's "Guide to Home Ventilation"


Water Management

It should be obvious that all efforts should be made to avoid problems with water in the bathroom. Leaks should be fixed. Condensation problems should be addressed. Wet walls should be constructed to effectively keep water from penetrating cavities in the walls and floor.


Air-sealing Opportunities

Despite good ventilation, moisture-laden air from the bathroom can still make it's way into wall and ceiling cavities. A bathroom remodeling project may present opportunity to improve air-sealing. Electrical, plumbing and ventilation penetrations should be sealed where they are accessible or in any walls that are opened. Depending on how they were constructed, soffits can be troublesome to air-seal, but if you are replacing bath fixtures or cabinets, you may be able to access space that would otherwise be difficult to reach.


Flooring

Flooring must not only have a good degree of protection from harm by water, but should also prevent water which does get on the floor from penetrating to the subfloor and space below.

Do not install carpet near water sources or areas where there is a perpetual moisture problem such as around sinks, tubs, showers and toilets. To reduce the potential for microbial growth in the joints of hard surfaces or porous flooring installed near water sources, be sure to seal the entire surface.


Windows

Bathroom remodeling may present a good opportunity to replace old windows with new ENERGY STAR® windows. While costs do not always justify the change from purely an energy savings perspective, there may be other benefits of new windows. More efficient windows may be less prone to condensation and related mold growth. Painted window sashes and frames in homes built before 1978 may contain lead-based paint; this is a special concern because the friction of opening and closing windows can release lead dust into the home.


General Recommendations

While remodeling or improving the energy efficiency of your home, steps should be taken to minimize pollution from sources inside the home. In addition, residents should be alert to signs of inadequate ventilation, such as stuffy air, moisture condensation on cold surfaces, or mold and mildew growth and use the remodeling project to correct underlying problems. While all of our general recommendations may not apply to your home, you should be aware of the issues including:

  • radon and lead
  • ventilation
  • good work practices

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Kitchen Remodel

Ventilation

Cooking in the kitchen generates a lot of moisture and odors, and requires ventilation. While there are various ventilation strategies for a kitchen, the range hood is by far the most common. The range hood should be used to capture and exhaust combustion products and vent them directly outdoors. These range hoods should be sized correctly. For a typical range, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the Home Ventilation Institute (HVI) recommend 100 cubic feet per minute (cfm). Larger fans may need to have make-up air provided, to prevent excessively depressurizing the home and potentially causing combustion equipment to backdraft. Choose a quiet or remote mounted fan so noise doesn't keep you from using the range hood every time you cook.

Air-sealing Opportunities

Despite good ventilation, moisture-laden air from the kitchen can still make it's way into wall and ceiling cavities. A kitchen remodeling project may present an opportunity to improve air-sealing. Electrical, plumbing and ventilation penetrations should be sealed where they are accessible or in any walls that are opened. Depending on how they were constructed, soffits can be troublesome to air-seal, but if you are replacing cabinets, you may be able to access space that would otherwise be unreachable.


Flooring

Flooring must not only have a good resistance to harm by water, but should also prevent water which does get on the floor from penetrating to the subfloor and space below.

Do not install carpet near water sources or in areas where there is a chronic moisture problem such as around sinks. To reduce the potential for microbial growth in the joints of hard surfaces or porous flooring installed near water sources, be sure to seal the entire surface.


Windows

Kitchen remodeling may present a good opportunity to replace old windows with new ENERGY STAR® windows. While costs do not always justify the change from purely an energy savings perspective, there may be other benefits of new windows. More efficient windows may be less prone to condensation and related mold growth. Painted window sashes and frames in homes built before 1978 may contain lead-based paint; this is a special concern because the friction of opening and closing windows can release lead dust into the home.


General Recommendations

While remodeling or improving the energy efficiency of your home, steps should be taken to minimize pollution from sources inside the home. In addition, residents should be alert to signs of inadequate ventilation, such as stuffy air, moisture condensation on cold surfaces, or mold and mildew growth and use the remodeling project to correct underlying problems. While all of our general recommendations may not apply to your home, you should be aware of the issues, including:

  • radon and lead
  • ventilation
  • good work practices

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Building a Home Addition

  1. Use energy efficient construction
  2. Control water and moisture
  3. Eliminate, reduce, or control pollutant sources
  4. Provide mechanical ventilation
  5. Use combustion equipment wisely
  6. Understand how to properly operate and maintain the home
  7. Resources

In the last several years, a growing body of scientific evidence has indicated that the pollutant levels within homes can sometimes be higher than in outdoor air, even in large, industrialized cities. Other research indicates that people spend approximately 90 percent of their time indoors. The potential health effects from indoor air pollution vary greatly and range from allergies and asthma, to cancer and even death.

Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in homes. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the home. High temperature and humidity levels can also increase concentrations of some pollutants.

There are many potential sources of indoor air pollution in any home. These include combustion sources such as:

  • oil, gas, kerosene, coal, wood and tobacco products
  • building materials and furnishings such as insulation, carpet and cabinetry or furniture made of certain pressed wood products
  • products for household cleaning and maintenance, personal care or hobbies
  • central heating and cooling systems and humidification devices
  • outdoor sources such as radon, pesticides and outdoor air pollution

The importance of any source depends on how much of a given pollutant it emits and how hazardous those emissions are, as well as the sensitivity of the population.

One component of maintaining good indoor air quality is the elimination, reduction, or management of the pollutant sources. Another important component is effective ventilation.

If too little outdoor air enters a home, pollutants can accumulate to levels that can pose health and comfort problems. In the past, homes had a significant amount of "natural" ventilation from leaks in the building. However, because some weather conditions can drastically reduce the amount of outdoor air that enters a home, pollutants can build up even in homes that are normally considered "leaky." Moreover, uncontrolled leaks can introduce moisture and humidity, pollen and dust inside framing systems and interior spaces. This can lead to future air quality and durability problems. Beyond indoor air quality problems, leaky homes can be very expensive to heat and cool.

Building leaky homes isn't the answer. Tight energy-efficient homes save energy and money. And with proper mechanical ventilation, they can have better indoor air quality than a leaky home. The reason is control. In a leaky home, outdoor air enters the house — through cracks, unsealed joints and penetrations, for example — intermittently, depending largely on the weather.

Some times there will be too much leakage, resulting in a drafty, uncomfortable house. Other times there won't be enough, resulting in a stuffy house. Mechanical ventilation in a well-insulated, well-sealed house, however, can exhaust pollutants and bring in outdoor air in a planned way. This makes a house both comfortable and energy efficient.

While it may be difficult or prohibitively expensive to make some of the improvements described below with an existing home, building these features into an addition can be easy and inexpensive. You might even save money! And construction practices that promote good indoor air quality also help protect the house itself. For example, controlling moisture will reduce mildew odors, premature paint failure, rot and structural damage.


The construction criteria mentioned to the left help to ensure good indoor air quality. For more information on how to best meet these criteria, check the resources list at the bottom of this page, especially No Regrets Remodeling and the EEBA Builder's Guides.

  1. Use energy efficient construction.
    Building tight, well-insulated homes reduces heating and cooling costs. When combined with mechanical ventilation and pollutant source control, tight, energy- efficient homes are comfortable, economical and promote good health. Indoor air quality and energy efficiency walk hand-in-hand.
  2. Control water and moisture.
    Controlling moisture in a home can help reduce mold, mildew and other biological growth which are linked to a variety of health effects. Methods to control moisture include building an energy-efficient home with proper air-sealing, proper use of vapor barriers and vapor diffusion strategies. The entire building envelope, from the foundation to the roof, should be designed to not only prevent moisture entry, but also to allow any moisture which does enter a means to escape. Proper ventilation can help ensure that indoor humidity levels remain at acceptable levels.
  3. Eliminate, reduce, or control pollutant sources.
    Eliminating or controlling individual sources of pollution are important steps in providing good indoor air quality. By using appropriate materials, isolating materials which may cause problems, and providing adequate ventilation, the levels of pollutants indoors can be greatly reduced. Included among these pollutants is radon, for example. If you live in a high radon area, you should consider using techniques to reduce radon entry when building your addition.
  4. Provide mechanical ventilation.
    Proper ventilation removes or dilutes stale air from your home, and provides cleaner air from outdoors. There are many approaches to ventilation which achieve these goals. So, "build it tight, and ventilate right."
  5. Use combustion equipment wisely.
    The selection, installation and integration of combustion equipment with other systems is an important part of building a home with healthy indoor air. If combustion appliances are not installed, maintained and operated properly these appliances can produce combustion pollutants that can damage your health, or even kill you. In addition, improperly vented appliances can add large amounts of moisture to the air, potentially resulting in both biological growth, and damage to the house. Fortunately, builders can take steps to reduce the risks for combustion equipment.
  6. Understand how to properly operate and maintain the home.
    How a house is operated, maintained and lived in is one of the most important factors affecting indoor air quality. Planning for this maintenance during the construction process, and learning what's important will not only promote good indoor air quality, but will also decrease problems with the physical structure of the house over time.

Resources

  • Builder's Guide - Mixed Climate; Builder's Guide - Cold Climate; Builder's Guide - Hot-Dry & Mixed Dry Climates, Joseph Lstiburek, Energy Efficient Building Association, 1998.
  • "The Inside Story: A Guide to Indoor Air Quality", U.S. EPA, Publication number 402-K-93-007. April 1995.

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IAQ and Attics

Air-sealing and the Thermal Boundary

Good air-sealing where the ceiling meets the attic is important not only to save energy and reduce fuel bills, but also to prevent moisture problems and even help reduce radon entry (as discussed below). Warm air has a tendency to rise, and this can increase pressure on the upper floor of a home. Thus, air leaks here can be especially problematic. In cold climates, for example, the warm, moist air leaving living space can enter the attic where is can condense in the colder attic possibly leading to water damage and mold growth. Frequent air leakage sites in the attic include staircases, the chimney chase, recessed light fixtures, plumbing and electrical penetrations, and some framing details. There are a variety of techniques for, and approaches to, sealing the ceiling of the top floor.

Insulation issues, including how much, where you put it, and it's relation to air and vapor barriers are also concerns for energy-use, comfort and moisture control. Improper use of insulation can lead not only to energy problems but also to condensation and mold growth.


Attic Conversions

Converting attic space to living space is popular and can be very economical. However, as you bring an attic into your living space, you should use care to ensure the attic is brought all the way into the living space to avoid comfort problems (too hot/too cold) and to prevent other conditions which could impact your health or the structure of your home. These include the air-sealing and insulation issues discussed above, as well as other considerations mentioned below. No-Regrets Remodeling provides a good overview of the issues.


Ventilation

Good ventilation protects both your health and your home. If it will be living space, the attic should be included your home's ventilation strategy. If your home currently has no mechanical ventilation this may be an opportunity to install a system.


Windows

Converting your attic to living space may present a good opportunity to replace old windows with new ENERGY STAR® windows. While costs do not always justify the change from purely an energy savings perspective, there may be other benefits of new windows. More efficient windows may be less prone to condensation and related mold growth. Painted window sashes and frames in homes built before 1978 may contain lead-based paint; this is a special concern because the friction of opening and closing windows can release lead dust into the home; new windows can solve this problem.


General Recommendations

You should also review the general recommendations for all remodeling and renovation projects.

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Regardless of which room or rooms you will be remodeling...

Please review "Addressing Indoor Environmental Concerns During Remodeling;" specifically the recommendations on best practices for indoor air quality when remodeling your home.  For homes built before 1978, always hire contractors that use only lead-safe certified renovators.