Daily Archives: September 4, 2014

A Healthy Home Part 5 — Pest Free


Each home can have many items that could be classified as pests. Some people think spiders are pests. Others let them live. I think ragweed pollen is no fun in the late summer, in my mind that qualifies as a pest.  This post will concentrate on those pests of the insect type, and perhaps a few that are a little larger, but not plants.

squirrelLarger then an insect?  Yes,  I’ve seen them.  Rodents a similar size animals can create problems.  If designers, builders, remodelers or homeowners address the concepts of pest free with insects, the potential for rodent size problems are reduced and perhaps eliminated.

Yes, that is a dead squirrel in an attic. Nice size rodent.  Somewhat of a pest. The homeowner in this case knew where the squirrels were getting in.  He had fixed their way in the previous fall, now he got to fix it again.

sump-pump-dome-lidUnder the posts about ‘A Dry House’  we looked at using a sealed cover on the sump to control the humidity.  Another reason for the sealed cover is to keep out insect sized pests.  Sumps are connected to to outside with perforated pipe to collect the water before it enters the basement wall.  This pipe is buried next to the foundation in sand and gravel.  It is probably not a large entry place on a newer home, but with age, it is nice to know the sealed cover keeps them out.

soffit ventsturtle ventMost residential attics in this area are ventilated. The use of lower vents (left) in the soffits and higher vents near the top of the peak (right)  allow a natural air flow. These vents should be screened to keep pests out. Most vents are supplied with screen. It should be installed and maintained. If it gets holes, replacement is fairly easy. When your roof is replaced these peak vents should be replaced. That will maintain the screen intact.  If you choose to use Ridge Vent, it should be screened also.  Keeping pests out of the attic will keep them out of the home.

1 Inch drillIf pests get into the attic there are always a few holes for them to squeeze through into the house. Electrical or plumbing penetrations are common. The other place in most homes are the top plate joints that are not sealed. This was covered in Part  2  a Clean Home.

Attic DuctOther vents to check would be the dryer vent and any exhaust fan vents. Make sure your exhaust vents run to the outside of your home. Many times they are just left open to the attic. In that case, you have several 4 inch openings right into your home.  Not only can pests enter, you will also find the seasonally heated or cooled air will also be coming in. The image on the right is a typical exhaust duct that does not go to the outside.

This post is Part 5 in A Healthy Home Series



A Healthy Home Part 4 – Free of Combustion By-Products

This post is written as a conversation between a homeowner and myself as it could have occurred during a Home Energy Audit. It is actually the gathering together of several conversations on different audits over the past few years.

smoky fires


A Healthy Home is Free of Combustion By-Products

Homeowner: Oh!  You mean no Carbon Monoxide!  I have a  Carbon Monoxide Detector.  It has had some false alarms, but it has never found a problem.

The Energy Guy: OK!  Carbon Monoxide (CO) is one by product of combustion.  There are others.

Homeowner:   So, you mean the house must be all electric?

The Energy Guy: No, not necessarily.  An all electric home, might have a fire place, and an attached garage. Both are sources of CO and other byproducts of combustion. A healthy home will deal with all of these in some fashion.

Homeowner: What other things are you talking about besides CO?

rustDHWThe Energy Guy: The one I see the most of is moisture.  Many of the flue pipes I’ve seen have rusted from the moisture.  If you have a gas hot water heater, look at the top.  Is the top rusting, what about the flue pipe or the draft diverter? Moisture from open combustion appliances also increases the humidity in the home and adds unneeded work to your air conditioning unit, increasing the bill.

There are others, such as Nitrogen  Dioxide, and Sulphur Dioxide, and various particles of all sorts.

Homeowner:  So, those are like Carbon Dioxide?  Something that is just there?

The Energy Guy:  Yes!  They are just there, with two concerns.  First the Lung Association points out the health effects of Sulphur Dioxide include:

  • Wheezing, shortness of breath and chest tightness and other problems, especially during exercise or physical activity.
  • Continued exposure at high levels increases respiratory symptoms and reduces the ability of the lungs to function.
  • Short exposures to peak levels of SO2 in the air can make it difficult for people with asthma to breathe when they are active outdoors.

Health effects of Nitrogen dioxide include:

  • Increased inflammation of the airways
  • Worsened cough and wheezing
  • Reduced lung function
  • Increased asthma attacks
  • Greater likelihood of emergency department and hospital admissions
  • Increased susceptibility to respiratory infection, such as influenza

Homeowner: I’m pretty healthy, but you said ‘First!’

The Energy Guy:  The second is moisture. Moisture could be a high humidity situation, or moisture from the combustion that produced these dioxides and if you inhale some of them, or moisture in your nose and lungs. Here are the basic chemical equations for those interested.

Sulphur Dioxide plus Water ends up as Sulphuric Acid [SO2 + H20 ===> H2SO3 (sulphurous acid) SO3 + H20 ===> H2SO4 (sulphuric acid)]

acid_storageNitrogen Dioxide plus Water ends up as Nitric Acid [NO2 + H2O ===> HNO3 + NO]

Homeowner: But acid eats things up!

The Energy Guy:  Yes, it does. These acids start the rust process, I mentioned earlier. The other place you can look for rust is to look at the flue on the roof of some homes. If the coating is attacked by the acids, then rust occurs.

So How do I keep this stuff out of my home and away from my family?

co detectorThe Energy Guy:  First install some Carbon Monoxide Detectors.  If your furnace and water heater are in the basement, you need one down there.  You also need one near bedrooms.

Homeowner: OK!  I’ll get that one that works with my Nest!

The Energy Guy:  That will work for one.   The Nest Protect is like most CO detectors, it will alarm at the higher amounts of CO as required by the Underwriters Laboratory requirements.   These start at 70ppm of CO for an hour. Professional organizations such as ASHRAE and NIOSH list 35ppm as the level for technicians and others to stop work, turn off equipment and evacuate the building. A low level detector is important.

Low Level CO detectors do not meet the UL requirement because they alarm at lower levels, typically 20ppm.    15-20ppm CO levels have been found to impair judgement in people exposed for short periods of time.  The UL testing does not allow a CO detector to pass if it alarms below 30 ppm. Low level CO exposure can result in headaches and general malaise.  If you are exposed to low levels over a period of months or years the effect is unknown at this time.

Homeowner:  OK!  So I’ll get a low level detector also.  What else can I do.

The Energy Guy:  Do some careful air sealing between the garage and the house. You can add exhaust ventilation to your garage as recommended in the International Residential Code. Open the door before you start the car, and then immediately back out. More information about CO and the garage. Air sealing here and a simple closer on the door to the garage will help keep CO and other pollutants from the garage out of the house.

Inside the house, you can buy smart when you replace your water heater or furnace.  Buy sealed combustion units.  These are generally more efficient units, so they will save you some on your bill each month.

95Water Heaters can be sealed combustion, such as the demand models or a power vented unit. Either of these units can be identified with the use of PVC exhaust flue, instead of the metal flue needed by traditional units. They do not need the metal, because the exhaust is a lower temperature. This has a side effect of increased efficiency. The image to the right is the flue of at sealed combustion furnace.

Finally, think about your wood burning fireplace or your gas oven.  These also create the same problems.  Here a low level CO detector would be very valuable. Following the fireplace manufacturers instructions in keeping the glass door shut and having it checked regularly are important.  For a gas range, especially with a gas oven, install an exhaust fan that vents to the outside.


Some of this information came from the Maine Indoor Air Quality Council

Some of this information came from the American Lung Association

A Healthy Home — The first of this series