Most homeowners are familiar with building codes mostly to ensure safety and compliance of features like decks, stairs, roofs, etc. When it comes to insulation there’s good reason to employ a state building code but many individuals may be surprised to learn that in Massachusetts we actually have regulations regarding what can and cannot be done in terms of basement insulation.

Basement insulation may seem like a wasted effort mostly because of the moisture that seeps through the foundation walls in the ever-changing climate here. Massachusetts lays in Climate Zone 4 & 5 according to the International Energy Conservation Code, which says anywhere above Zone 3 becomes cost effective to insulate a basement. Finishing a basement helps to increase your home’s market value and expands your living space so it is a practical renovation. However, following the 2017 Massachusetts Basement Insulation Code is imperative.

Why is there a Basement Insulation Code?

Basement insulation performs two tasks. First, it keeps heat in especially in a finished basement outfitted with HVAC ducts. Second, it will prevent moist air from contacting a cool foundation wall. When this is allowed to occur it leads to condensation which then brings with it mold growth and subsequent rot.

One major reason that basement insulation code is implemented is because of energy efficiency. 1,500 square foot homes in our climate region (Buffalo, NY for example) can save up to $390 per year with R-20 basement insulation according to the U.S Department of Energy.

Insulation is also only a portion of what is required as part of Massachusetts basement building codes. Other requirements are in place for emergency egress exit points, natural lighting, and access (stairs, doors, etc). The insulation would be part of the air quality recommendations because proper installation helps reduce mold and mildew growth.

What are the Code Requirements in 2017 for Massachusetts?

The Massachusetts building code first states that it is important to, “Provide the recommended level of insulation under floors above unheated spaces, around walls in a heated basement or unventilated crawl space and on the edges of slabs-on- grade.” This means there are three different locations that must be addressed regarding proper insulation.

The other aspects that must be addressed in terms of insulation include what kind and how thick? For basement walls in Massachusetts the recommended form of insulation is rigid insulation which includes:

  • extruded polystyrene foam (XPS)
  • expanded polystyrene foam (EPS)
  • polyurethane foam
  • polyisocyanurate foam

Foam provides the dual value of retaining heat but also blocking moisture from accessing. Traditional home wall insulation such as fiberglass batts is very prone to moisture invasion which is why it's not allowed in basements.

Basement wall value in Climate Zone 4/5 should meet R10/R13 requirements. The savings laid out by the U.S Department of Energy are calculated for R20 which means it is possible (and recommended) to go higher.

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Finally this insulation is required on walls if the basement is conditioned (finished). The insulation must also be covered with 1/2” gypsum board (or a similarly approved material) for fire safety. If the basement is unfinished the floor above must be insulated to help avoid heat loss.

For more information on the benefits of upgrading your home installation to the most current Massachusetts Building Insulation Code, and the ways in which this can be achieved, call Mass Energy Lab Insulation at 617-902- 2744 or visit our insulation services page.