5 Questions with Billy Tesh

1. Am I required to have insulation in my crawlspace?

Insulation requirements such as where it’s installed, R-Value, flame-spread rating, spoke developed rating and other factors can vary according to the state and local building codes where the crawlspace is located. In most areas, insulation is required either in the floor joists or on the interior of the exterior foundation walls. The insulating value (R-value) is usually determined by International Energy Conservation Code (IECC). Every county in the USA falls into 1 of 8 zones. Each zone has their own requirements for the R-value based on where the insulation is being installed (floor joists, foundation wall, etc.). A helpful resource to locate your county’s zone is: https://reca-codes.com/2018-iecc.

2. Do I need to replace existing insulation?

First, you will need to inspect existing insulation. If the existing insulation is dry, provides full floor joist coverage, is the correct R-value and doesn’t have any mold or fungus on it, we recommend leaving it in place. Studies by Advanced Energy (crawlspaces.org) showed an average of 15% energy savings on heating and cooling when floor joist insulation is used in an encapsulated crawlspace versus the same insulation in a vented crawlspace; wall insulation provided an 18% energy savings under the same conditions. In other words, pulling out perfectly good insulation to replace it with wall insulation does not provide sufficient benefits in most cases to justify the cost. Of course, if existing insulation is in bad shape, we recommend removing it and insulating foundation walls.

3. Are all types of insulation the same?

All insulations aim to reduce heat loss/gain but there are advantages and trade-offs for each kind. The four most common types are batt, rigid foam board, spray foam and bubble insulation. Batt insulation is the go-to when you cannot insulate the foundation wall. However, it’s prone to falling down, is a skin irritant and is labor intensive to install. Rigid foam boards like Bora-Foam work great on the foundation walls and are even termite resistant. The most labor-friendly option is bubble insulation as its flexibility allows you to form it around walls and piers and it can even be applied to foundation walls. It also has a built-in radiant barrier. Lastly, there is spray foam, an option we wouldn’t recommend as it cannot be removed from the wall, requires additional respiratory safety equipment and is hard to install with the required termite inspection gap.

4. I’ve heard termites like insulation, is that true?

Termites do sometimes ingest certain insulation materials (particularly foam) in order to create a passageway up to the wooden structure. There is a required termite inspection gap between the top of the insulation and the seal plate of the foundation wall (usually 3 inches) for this reason. While most foam insulations are susceptible to termite activity, we recommend Bora-Foam because termite resistance is built into it to help prevent tunneling through the product.

5. What is the best way to determine insulation requirements in my area?

We always recommend speaking to your local building inspector to verify the requirements for your area. Building codes change periodically and can sometimes be hard to understand. While most places follow similar guidelines, you never want to find out the hard way that time or money was wasted by not installing insulation to code.