North Carolina's Tightest Tested Home?


                                                                            Picture of Asheville North Carolina's tightest tested custom home

We tested this custom home, pre-drywall in November of 2012 outside of Asheville, NC. To our knowledge, it's the rater's tightest tested home and still holds the top spot in the Carolinas. We used our standard level of air-sealing for this panelized-wall, trussed-roof home to achieve 18 times tighter than what local codes are supposed to enforce. This suggests that homes could easily meet intended code minimums with minimal effort by builders.


blower door test illustration

All new construction needs blower door testing for airtightness

The blower door test is a home's most important diagnostic tool. Its measurement offers the most revealing information on energy efficiency and control of indoor-air quality. Insulation and space conditioning details are better addressed after airtightness. This is the most important measurement for existing home's weatherization efforts and a new home's total performance.

Blower door thumbnail   The Blower Door Test. 

This is the best tool available for measuring energy efficiency, control over indoor-air quality and is an indicator of weather-barrier craftsmanship, beneath the finished surfaces.


It may soon be illegal not to blower door test new home construction.

It's already illegal at the international level, local codes have yet to adopt it. 

Mandatory blower door testing will be a gigantic improvement to our nation’s homes. Future inhabitants will look back on mandatory blower door numbers as we look back on the first insulation requirements. Blower door numbers are much more revealing than R-Value (insulation measurement).

This testing also reveals health issues relating to basic safety: backdrafting combustion appliances, soil gases like radon and attached garage dangersWe need the community to become more familiar with the terminology, numbers and likely results. This table shows where minimum blower door numbers need to be.        

Table by Asheville custom builder on blower door test numbersKnow your numbers, know your quality of build. Results are very useful in evaluating homes and builders.

  • Indoor Air Quality
  • Energy Efficiency
  • Comfort
  • Durability

True craftsmanship includes what's behind the finished surfaces.

Many details protecting homes and influencing performance are covered up by finish materials like drywall and siding. Finishes conceal problems like inadequate framing connections, missing insulation, loose ductwork and flashing errors in weather barriers. Custom home builders having the same attention to detail for achieving good blower door results, will usually apply the same craftsmanship to all important hidden qualities in a home.

.6 ACH50 Passive House Certification 

Picture of foundation under construction

Passive House is criticized for this minimum, even losing market share as many going for the certification fall short for the requirement. Some suggest the program leads to simplistic architectural design, boring designs being easier to make air-tight. This home with its 18 exterior corners and two sizable dormers can help dispel that reasoning.

Picture or Eco-Panels home under constructionOur homes average .8 ACH50. This home used our typical air-sealing details with the addition of Protecto Wrap's triple gaurd sill sealer. Careful with the tape's reverse lap. As builders tighten up airsealing, its important to remember the top 3 ways water destroys homes and buildings.

Picture of roof under constructionAir-sealing is cheap compared to insulation and mechanical systems. Much of our cost-effective success is owed to panelizing exterior walls, including the basement of pre-cast concrete panels. We also like floor to wall connections that eliminate rim joists. Eco-panels supplied the upper level SIP panels with a Huber ZIP exterior upgrade. With the proper planning and execution, panels can keep labor costs low and energy performance high.


.282 ACH50 is the state record result for this home in Barnardsville. 2x tighter than Passive House certification minimum and over 800% better than what state energy code is supposed to be enforcing as a minimum which suggests its not that difficult for builders to comply with mandatory (and eventually relaxed) testing.

If anyone knows of a tighter tested home in the Carolinas, please tell us about it. We are looking forward to congratulating the next record holder and their forward progress. Our state and country needs more builders, architects and clients to recognize this enormous opportunity for building better homes.

Outdoor-Air Ventilation   Heating and cooling related pie graph showing energy costs Heating and Cooling in WNC   Sunrise image3 Forms of Solar Energy For Homes and Buildings

Springtime Builders is a custom home builder serving the Asheville NC area.

Posted in Building Envelope

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