Los Angeles · Orange · Ventura · Santa Barbara & Surrounding Counties
Subfloor Insulation
Protection from Cold or Drafty Floors
Air Sealing is a service that we offer complimentary to all of our install jobs, and can benefit your home by sealing up small-scale penetrations in your attic to help keep out unwanted drafts. You can also opt out of this free service if desired.
We apply and inject foam throughout the attic where needed – This includes recessed lights, plumbing, piping, conduit, or any areas where air can get through. This is most effective to do when the attic is empty, such as following a removal.
Subfloor insulation is designed to improve comfort in homes with raised foundations by addressing cold, drafty floors. It works by insulating the space beneath your flooring, helping maintain more consistent indoor temperatures—especially during colder months.
While subfloor insulation helps significantly to retain warmth during colder weather, it is not designed to greatly reduce heat during hotter months. Instead, it works best as part of a complete insulation system alongside attic insulation, wall insulation, and other energy-efficiency upgrades.
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How it Works
We install insulation directly between the floor joists (wooden beams) underneath the home using batt insulation only, because there is no way to suspend blown, loose fill insulation to subflooring. To ensure long-term performance, we secure all insulation using support rods (often referred to as lightning rods), which hold the batts firmly in place beneath the subfloor.
Material Options
Our standard material for subflooring is Fiberglass batt (rolled) insulation, which provides solid thermal performance and is a cost-effective option for most homes. For homeowners looking for a higher-performance upgrade, we are pleased to be one of the few installers offering Rockwool batt insulation. Add graphic here of our new ‘the everguard advantage. Rockwool is denser and heavier, which makes it more durable and resistant to airflow, offering improved overall insulation quality. For more information on comparing materials, see . Add link to materials comparison page.
Spray Foam vs. Batt Insulation for Subfloors
For most homes, batt insulation is the most practical subflooring option. We generally do not recommend spray foam insulation for subfloor applications.
While spray foam provides strong air sealing, it can also create an overly sealed environment that may trap moisture beneath the home—especially in coastal or humid conditions where airflow is important. In addition, once spray foam expands and hardens, it becomes very difficult to remove or modify. If future repairs, maintenance, or access to plumbing and electrical are needed, removal can be time-consuming, costly, and potentially damaging to surrounding materials. Over time, prolonged exposure to temperature fluctuations and moisture may cause the spray foam insulation to degrade, and in some cases, this can lead to the release of compounds into the air, particularly in poorly ventilated areas. For these reasons, we recommend batting which instead allows the subfloor to ventilate properly while remaining accessible, serviceable, and reliable over the long term.
Moisture Considerations (Especially in Coastal Areas)
In coastal or higher-humidity environments, moisture management is an important factor when considering subfloor insulation. Without insulation, damp air can rise from the crawlspace—especially as moisture collects beneath the home and evaporates upward—leading to cold, clammy floors and increasing the risk of mold and mildew in the home. At the same time, poorly installed insulation can trap moisture and create similar issues inside and around the home. When installed correctly, subfloor insulation helps regulate temperature while still allowing the area to breathe, reducing moisture buildup and supporting a healthier environment beneath the home.
When properly installed, subfloor insulation can make a noticeable difference in floor temperature, reducing unwanted drafts, and improving overall comfort, helping your home feel more thermally consistent and livable year-round.