installing rockwool insulation between roof rafters bays

The exterior of your home is commonly referred to as the “building shell.” The building shell (or building envelope) is the border between the conditioned (heated or cooled) and unconditioned air, and it protects you from the elements. It regulates how air moves in and out of your home, repels water, and prevents conditioned air from leaking to the outside. The building shell also regulates the source of the air moving into and out of our home. For example, an open window may offer fresh air while penetrations in walls, floor, and ceilings may allow unhealthy air into your home. Issues in your building shell can have a big effect on home utility bills, durability, and comfort.

Our building shell service begins with a thorough home energy audit, where we identify the root cause of energy-efficiency issues and prioritize solutions. We use energy modeling software, a variety of home performance tests, and building science to guide the process. Many energy-saving solutions include air draft reduction and insulation.


  • Promote home air quality by reducing air infiltration from areas of the home where poor air quality is likely to exist (attics, crawlspaces, garages, wall cavities)
  • Cut energy bills by keeping conditioned air in and the elements out
  • Stop drafts for greater indoor comfort
  • Promote home durability

At Kevel Home Performance, we have the tools and experience to determine how your San Francisco Bay Area home shell is performing. We use an infrared camera and blower door test to identify issues so we can find effective solutions. Kevel Home Performance addresses the root cause of home building shell issues, lowering your energy bills for many years to come.


Most homes are not properly air sealed, according to the Department of Energy. Sealing leaks and holes can have a significant impact on home comfort and utility bills. We use tests to identify air leaks, systematically sealing them to fortify your home’s building shell.


Upgrading home insulation is a great way to cut your energy bills and increase indoor comfort in the San Francisco Bay Area. High-performance insulation works by keeping cold out during the winter and heat out in the summer, saving energy throughout the year. Kevel Home Performance installs a variety of different types of insulation, including cellulose, fiberglass, open-cell foam, and closed-cell foam.

Ready for a more comfortable and efficient home? Get in touch today!


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Our Customers Speak for Us

  • Very professional and knowledgeable, excellent customer service. With a new baby, improving the indoor air quality and thermal comfort of our home was a priority - Kevel delivered with great work completed in a timely manner and on budget.

  • My house was very drafty with no working heat before Kevel came. Now, our formerly broken central heating is working great, and I notice a significant decrease in drafts throughout. I would say that Kevel is very responsive and responsible.

  • Excellent workmanship and attention to detail--as well as to our questions. The understanding of the whole house energy system was exceptional, and the "as-built" system diagrams were a real plus.

  • Very professional, knowledgeable, pleasant to work with. They found several major problems with our ductwork that have been around for at least 30 years. Noticing a difference already in how the house seems better able to maintain a constant temperature.

  • Great workmanship and completed in a timely manner by conscientious people. My home temperature is uniform throughout, before the upgrade the downstairs was always a lot colder.

  • Everyone was very friendly, considerate about tracking dirt into the house, kept worksite neat - not to mention did a great job. Brian even came one evening to fix the furnace door which came unlatched so that I could have heat.

  • I am very happy with the efficiency, the fit, the look, and the partial sound reduction. Indow Windows are a very good product with obvious benefits. Kevel provided very knowledgeable and professional service.

  • Feels like a whole different house. No longer do I wake up feeling like I'm camping (i.e. with chilly air feeling like I'm outside). The air sealing I think made the most difference - much more than I had expected.