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From a Certified Pro
Certified Energy Auditor
Residential Comfort & Energy Efficiency
Thursday, December 31 2020
Towson - Maryland
If you have a Cape-Cod style home and you are wondering if you can air seal and insulate effectively - the answer is yes, however not without a good plan.
Houses with Cape-Cod style framing stem from being built in the 1940's and 1950's when the cost of heating was dirt cheap and insulation was an afterthought.
If you live in this style home, chances are very good that it has not been properly addressed due to the complexities of the way it was built.
Take a look at this recent Cape-Cod insulation project and what steps were taken to seal and insulate. This one is located in the friendly residential Southland Hills community of about 200 homes in the heart of Towson, Maryland. The homes in the neighborhood were built in the 1940s.
The Comprehensive Energy Audit
Having a home energy audit done when you live in a Cape Cod style home might be a good idea if you are looking for guidance on how to properly go about creating better comfort and lower energy bills.
The good thing about working with an energy auitor that has experience is that you can gain insights and avoid pitfalls from a person that has seen these areas before and knows what to expect.
Partnering with a pro can help set you on the right path towards measureable results.
Foundation -- Air Sealing / Insulation
Air seal any penetrations at the accessible rim joist in the basement with two-part spray foam (~60 linear ft) which will also insulate the area to R-19.
Attic -- Air Sealing / Insulation
Cut access in three wall locations to gain access to upper floor attic. Reinstall the drywall with removable panel for future access if needed.
Treat three existing attic access areas by adding insulation to each and weatherstripping. (2 wall, 1 ceiling)
Add 5-7” of open cell spray foam to the accessible sloped roof surfaces of the kneewall attic areas (~392 sq ft).
Blow 10” of loose fill cellulose to the flat collar attic using the existing ceiling hatch in the closet (~154 sq ft).
Basement Rim & Band Joist - Every Home Should Get this Treatment by the Way
If you are not sure what the rim and band joist are in your basement and if it is accessible for treatment - you are about to find out!
First, put yourself in the unfinished part of your basement. Usually it is a utility room with HVAC, water heater and maybe washer/dryer.
Identify your foundation wall at the top and you have found your rim and band joist.
Take a look at how the electrical "main" is coming through the rim joist in the basement of this Towson, Maryland home performance home. This is happening in a lot of homes.
Look at the size of that hole. And this is the point - it is a hole going directly to the outside which means this:
Summer: humidity infiltration
Winter: cold air infiltration
Just look at those spider webs. The spiders like to make their traps where air is moving. It is instinctual. So if you see a spider web, air is flowing.
Now get your full frame of reference by watching this short video clip that shows where the electrical main and gas line enter into the rim joist from the outside which appears "invisible", but it is not.
Results - A Look at the Final Project and the Test-Out Numbers
Rim and Band Joist Treatment - Closed Cell Spray Foam
Watch the spray foam team treat a portion of the rim and band joist in this up close and personal clip.
Knee Wall Attic Treatment Before / After
Example of Knee Wall Encapsulation
Blower Door Results
Many factors drive the overall reduction in leakage that each home is schedule to achieve during a home performance project through the BGE program. I make this very clear to my customers that for every house I am believe we can get 30% reduction and don't there is a home that I am convinced we can only achieve the minimum required to meet the program standards (10%) - only to exceed that by a lot.
As a result of many audits and challenging situations when I was wrong, the partnership I formed with this customer went a long way. We both agreed that 20% reduction was a good target and that due to other factors that were not reported here, we will do everything we can to nail the work scope and see where it takes us.
Ultimately, this home performance project achieved an 11% reduction in leakage.
Initial Blower Door Test In CFM: 3775 Cubic Feet Per Minute at Negative Pressure -50 Pascals
Final Test Out Number: 3255 Cubic Feet Per Minute at negative pressure -50 Pascals
Need Advice on How to Do Something Like This?
If you are interested in making your home more comfortable and more efficient, give me a call. We can discuss your situation and likely getting a BGE or Pepco Energy Audit is the way to go.
Incentives through the program can be quite advantageous, particularly for those that know that they have to get this problem resolved once and for all.
Furthermore, an energy audit can uncover other factors that can contribute to your specific issue as each home is different - even the same model across the street.
Give me a call! I'd love to help you out!
Written by Eric Gans
I have over 1000 energy audits under my belt in Maryland. I like to take my personal experiences with each of my audit customers and try to get the things that concern them out into the world so others can make good home improvement decisions - in the right order - according to their needs.