Unfinished Basements - How to Insulate

uninsulated foundation wall

If you are interested in SAVING MONEY ON ENERGY BILLS, CONSERVING FUEL, and INCREASING THE COMFORT in you property – foundation walls are an important place to start. Most New England homes were not (and many still aren't) built with a thermal or vapor barrier on the exterior of the foundation walls. Not having this barrier allows moisture to enter your basement as well as heat to exit your foundation walls through the concrete. Concrete wicks moisture and has an R-Value of approximately R1 per 8" (stone, brick & masonry fall into this category), so it offers great strength for building but lacks energy efficient characteristics.

Foundation Wall Heat Transfer

Even if your basement or crawl space is not heated, you are still allowing heat to escape. Heat is generated within your basement/ crawlspaces many different ways: furnaces/ boilers, hot water heaters, lights, cloths washers & dryers, and through the earth. Once you get about 2 feet below grade you are generating heat from the earth so why not take all the help you can get to heat your home - contain and utilize that heat!

Beyond surface area heat loss through foundation walls; perimeter joists are where a large amount of air infiltration into your structure are occurring! Simply put, the house functions like a chimney. Heated air exits at the highest point (the attic) and draws cold air in with the most pressure at the furthest point from the attic (usually the basement/ crawlspace). So if you block air leakage at the basement you will effectively choke off large amounts of infiltration that enters through these avenues.

Foundation Wall and Rim Joist Insulation

TIP #1: if you have fiberglass insulation in the joist cavities above your foundation wall check to see if they are dirty – if so that is a sign of air intrusion. TIP #2: if you have cob webs all around the same area, it too is a sign of air intrusion!

Applying rigid foam board and/or spray foam insulation to the interior of your foundation walls & perimeter joists are some of the best retrofit avenues to take in order to control surface area heat loss, moisture intrusion, and air infiltration into your basement.

If you already have a finished basement these solutions will not be achievable for you, unless of course you rip the walls down. If you do have a finished basement and are experiencing moisture problems, make certain you are not promoting mold – if a mold issue is starting, tackle it ASAP, it will only make your life easier.

Stay tuned for later posts that will address ways to manage moisture in a finished basement.

Having an Energy Audit performed on your property is the best way to prioritize your energy inefficiencies, and where to start improving you homes performance and sustainability.