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How to House Hunt Like a Home Inspector -Insulation/Ventilation

How to House Hunt Like a Home Inspector -Insulation/Ventilation


The subjects of this post may be the systems of the home that have changed the most over the years, but are thought about the least by the occupants of the home- at least if the insulation and ventilation are doing their jobs.  This series “How to House Hunt Like a Home Inspector” discusses how home buyers can use the perspective of a home inspector to get to know the house better before they buy.  See other posts at www.

Before talking about how a house hunter can view the home with the eye of a home inspector, I think it’s important to talk about the history of insulation and ventilation in home building practices. In the not too distant past, most homes were drafty and poorly insulated. If you were cold you added more fuel to your heat source, usually a fire, or you wrapped yourself in a heavier blanket. If you were too warm, you wore fewer clothes, opened the windows and stayed out of the sun. Buildings used shade and air movement to keep the occupants cool.  In areas where heating was required, ventilation was not as great a concern since air naturally exchanged through building materials that were more loosely connected than we see today.

As technology improved and heating or cooling costs increased, and a greater awareness of the need for greener technology developed,  consideration was given to preventing heat transfer in or out of a home by insulating walls and roofs. The concept of R-factor (R for resistance to heat transfer) became common in building vocabulary. As this was understood better, builders realized the importance of heat transfer through air leakage. So, the building envelope was made tighter and air/vapor barriers (usually a plastic sheet wrapping the inside of the building) were used to reduce air movement through the walls or ceiling. Most homes were still somewhat leaky though, and bathroom and kitchen fans pushing air out of the home, allowed fresh air to be drawn in to replace it.

High efficiency furnaces and boilers are now used to reduce the loss of interior air up the chimney and newer windows and doors are installed with perimeter sealant (often spray foam) to prevent as much air transfer as possible.  But this efficiency created a problem. If a home was too tight, the moist, stale air created by cooking, bathing and human activity could not escape. If there was a temperature difference between the inside and outside, condensation could form on or in the walls or roof. Wet or humid environments inside a home, or wet building materials in walls and roofs are ideal for the growth of mold and mildew and builders began to see problems arising in otherwise well built homes.  The field of study of indoor air quality was born.

Nowadays, it is understood that insulation and ventilation are both necessary to keep a home feeling comfortable. Building practices have changed so that heat recovery ventilators (HRV) have become common in new homes. These units recovery heat from air that is being expelled and transfer the heat to fresh air being brought in. As this transfer is made, moisture can be removed or added to the air as needed.

So, this is a pretty complex balancing act. How can you expect the average house hunter to know what to look for when viewing a property for the first time? And what if it isn’t a new home? How can you tell if the insulation has been upgraded, if the air/vapor barrier provides a tight envelope, or if there is ventilation provided? Well, it is complex and you can’t possibly see everything during a short house hunting visit. But if you use the approach of a home inspector, there are some things that you can look for to warn you of possible issues with the home.

For ventilation, there are a few things you can look (or rather smell for). Does the air smell fresh or does it smell stale, or worse, musty. Test the bathroom and kitchen fans, if present, to see if they are really drawing air (you can use a piece of torn tissue to see if it is drawn toward the fan). If there is a kitchen fan hood, check for a cabinet above to see if there is any ducting to take air to the outside of the home. You might not be able to see the actual ducts. But if there isn’t even a bulkhead or chase where a duct could be hidden, you’ll know it isn’t there. Check also around doors and windows to see if there are signs of condensation. Poor ventilation will allow moisture to build up within the home. During cold weather, it will typically condense where the coldest surfaces are, at doors and windows. Finally, if you look around the furnace or boiler area check for a large box with ducting coming out in several directions. This could be a heat recovery ventilator that draws and discharges air to/from different places both within and outside of the house. Read whatever labels you can see to confirm this!

Insulation is also difficult to assess. Assuming you’re not going to be climbing into the attic, the best place to look for insulation, and sometimes as importantly a vapor barrier, is the basement. Look at the edges of unfinished spaces to see if there is any sign of insulation or a clear plastic sheet that acts as a vapor barrier. On upper floors, if it is very cold outside, you can often tell if there is a lack of insulation between the floor joists at the edge of the house just by walking around the perimeter. Floors that become very cold near exterior walls may be a sign of poor insulation. Look around doors and windows to see if the seams where they meet the walls have been caulked or sealed. Preventing air movement through exterior walls of old homes can go a long way to making it feel more comfortable, and saving energy.

The components of the building envelope are designed and put together to provide occupants with a comfortable environment to live in. But we rarely think about them when they are working correctly or when they are not needed. By being aware of the issues and looking at a house with the approach of a home inspector, you may be able to spot issues and assess their implications (and associated costs) before you decide to make it your home.

If you have any comments or questions on this or other posts, or on any building topics, please use the comments section. We’d love to hear from you!!


Steven Schroeder 2016-10-18

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