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Question DetailsAsked on 4/5/2012

What type of building performance specialist can assess unusual air flow dynamics present since an addition was put on my home?

Wind and outdoor climate conditions enter my home. Moving air is felt throughout the entire house, esp. at floor level and also from above. Drafts are generally cool to very cold. Infiltration of outside conditions is a year round problem.(I'm in MA). It is impossible to maintain comfort levels via HVAC system. Dampness/humidity/outside pollutants, also enter. Main house is 864 sq ft ranch. Addition is approx. 432 sq ft - family room with vaulted ceiling, closet, & bathroom, and 2 car garage.
Trusses were used for room and garage. Wooden shingles were removed from main house and vinyl siding was installed on entire house.
During the same time period the building exterior was changed, vinyl windows were installed and the HVAC system was connected to the addition. The problems have been present ever since. Smoke detectors don't get triggered. On a foggy morning we watched fog get sucked into the garage gable vent when the furnace turned on. Multiple melt spots began on the roof.

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2 Answers


A BPI certified Building Analyst Professional should be able to help you with this evaluation. The items you described are part of a whole house evaluation. He will use a blower door and duct blaster to determine where you are leaking energy, having infiltration problems and also evaluate the combustion safety of your appliances. See for a list of contractors in your area and a broader explanation of the process.

Answered 8 years ago by Cline1


You may have a problem with your furnace's cold air intake. Your furnace may be starved for fresh air, so it's sucking air into those gable vents. It's probably also sucking air in through every other air infiltration point causing the cold drafts.

If this is the cause of those problems, then your furnace may need to have a duct run to the outside of the house to draw in fresh air during combustion. In order to keep cold air from entering through the ductwork at other times, you'll probably need a mechanical damper system that opens and closes with the combustion in the furnace.

Once you have ducted fresh air to your furnace, you can go to work sealing up all those air infiltration points that used to feed your furnace's fresh air needs.

The blower door test will test the relative level of air infiltration through various points in the home. After you've sealed the leaks, you can run the blower door test again and verify that the amount of air infiltration has been reduced by a significant amount, or not.

To seal the leaks, you'll usually need to remove baseboard and door & window casings on all of your exterior walls. The gaps between the wall framing and the windows/doors can be sealed with foam insulation or caulk. The point where the bottom wall plate meets the subfloor should also be caulked. The covers around any electrical box should be removed by a qualified person and the gaps between the drywall and the electrical boxes should be sealed. Caulk is often used here too. You might want to consider using fire resistant caulk where the wires enter the electrical box. These repairs should be done around the entire perimeter of the home.

Lights that penetrate ceilings on the top floor should also be sealed. Depending on the light fixture, you may be able to caulk the area between the ceiling drywall and the light fixture. Another fix might be to build a small box made of drywall and place it over any can light fixtures that extend into the ceiling. Make sure you don't contact the fixture if it isn't rated for that. Taping the drywall box to seal any penetrations will stop the leaks at the light fixtures. Attic access doors are also a source of air infiltration.

Check any penetrations through the outside wall such as gas lines, electrical service lines, water lines for lawn irrigation systems etc. These penetrations should be thoroughly caulked from the outside and inside.

Answered 8 years ago by JGHamm

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