Resource Article

How to Insulate a Crawl Space

Blake Heron

How to Insulate a Crawl Space

Did you know that proper insulation can make a massive difference in your energy usage? Better insulation in your crawl space means your HVAC system doesn’t have to work as hard, meaning lower energy bills.

A crawl space doesn’t have to be insulated for the structural integrity of the home, but when you insulate a crawl space, it can end up saving you money on your bills in the long term. It can also help keep temperatures steady throughout the house. For this reason, most homeowners consider it a valuable investment.

How do you properly insulate a crawl space, though? Use this guide to help you identify the best ways to ensure your crawl space insulation is sealed to perfection.

The first step is finding out what kind of crawl space you have.

Different Kinds of Crawl Spaces

Is your crawl space ventilated or unventilated? It is essential to diagnose the type of crawl space ventilation that you have before starting construction. This is because it will affect the types of insulation materials that are recommended, as well as the strategy of installation.

Ventilated Crawl Spaces

Ventilated crawl spaces allow for increased airflow and outside moisture. This means there is higher chances of moisture buildup, which can lead to mold and mildew along with warping and water damage.

Experts use fiberglass insulation below the subfloor. The subfloor is the area above the crawl space and below the home. This can be conveniently installed without issue.

Ventilated spaces are most suited to utilizing R-15 or R-19 fiberglass insulation depending on the size of the floor joists.

Unventilated Crawl Spaces

The major difference in installation strategy is that insulation will fit on the walls rather than the ceiling of the crawl space. Unventilated crawl spaces have less airflow and different conditions. They are easier to insulate, generally, and use much less insulation to properly coat them.

Experts will install a vapor barrier to eliminate moisture, using a polyurethane liner on the floor and a dehumidifier to remove moisture.

The type of insulation is another difference between unventilated and ventilated crawl spaces. Unventilated spaces should use foam board insulation that meets the code requirements of being in a crawl space, in contact with the earth.

Building Codes and Regulations

There are several essential regulations and codes that must be met when installing insulation on the crawl space of your property.

Be sure to abide by the codes for your area whether in North Carolina, Virginia, or any other state. For instance, in North Carolina, the access opening must be a minimum of 18 by 24 inches, meaning insulation should not impede this access point.

How to Prep the Crawl Space for Insulation

There are a few things that you can do before installing insulation. The most important is to remove moisture and water sources.

Leaks, pipes, or openings can be cause for concern. These will harm the integrity of the foundation if moisture gets under any protective sealing to develop into mold.

Other things that can help with the installation process include clearing out as much space as possible and paying special mind to rocks and debris that could puncture insulation.

You can also familiarize yourself with the parts of the crawl space, like:

  • The Joists or Joist Bays are structural frame elements between beams
  • The Vapor Barrier will seal out moisture within the insulation
  • Batting is a type of insulation that consists of flat, pre-cut fiberglass

Insulate a Crawl Space: Step-by-Step

Insulating a crawl space doesn’t have to be a challenging feat when you know exactly what to do. Starting with the vapor barrier and moving on to the installation of batting and more, use this section to help guide your understanding of the insulation process.

Step 1: The Floor Vapor Barrier

The first thing to go down on the floor of the crawl space should be sheets of plastic. Lay these plastic sheets to create an insulating barrier against moisture from the damp ground.

For ventilated spaces, be sure not to block vents with insulation. You can use batting in between the joists instead.

Step 2: Wall Insulation for Unventilated Spaces

If your space is unventilated, wall insulation is the best strategy for installation. A qualified professional installation crew will know to use the right insulation to insulation the walls, from ground to ceiling, to eliminate moisture and maintain energy efficiency.

In Virginia, a 2-4″ inspection gap is required to be able to inspect for termites so the insulation can’t cover this inspection gap.

Step 3: Subfloor Insulation for Ventilated Spaces

If your space is ventilated, the installation of fiberglass on the subfloor will be the perfect way to support the HVAC system and insulate the crawl space.

What Other Materials Are Available?

Did you know that there is more than just one option when it comes to insulation for your crawl space? A few of the kinds you may want to consider include mineral wool, XPS foam, EPS foam, and spray foam.

They all provide unique advantages and disadvantages, so be sure to consider them all to find the right fit for your needs.

Spray foam is fast, but terrible if any future repairs are ever required. XPS foam also has a reputation for being non-eco-friendly. Mineral wood boards are less harmful to the environment, but they don’t work as a vapor barrier and therefore that must be added.

Where Can You Turn For Quality Crawl Space Insulation?

How do you know that the professionals you are working with will deliver the highest-quality materials and strategies of installation? Opt to work with BAY Crawl Space & Foundation Repair for the best intuitive and efficient insulation services for all types of crawl spaces.

These unintrusive services allow you to easily outfit your crawl space with foolproof insulation solutions. Insulate a crawl space more efficiently than ever before. BAY Crawl Space & Foundation Repair delivers advantages that you can see on your energy bill.

BAY Crawl Space & Foundation Repair today. You can expect high-quality and effective crawl space insulation and vapor barrier installation services.

Written By Blake Heron

Blake has specialized in crawl space & foundation repairs for over 10 years (since 2012). His prior engineering and business degrees from James Madison University in VA prepared him for a mastery of problem solving with crawl space & foundation repair issues. He is one of America’s top experts on crawl space encapsulation. As Founder of both ‘BAY Crawl Space & Foundation Repair’ as well as ‘GridLock Foundations’ he is a leading industry expert on crawl space foundation repairs.

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