5 Types of Garage Insulation to Consider

Fiberglass Batt Insulation

Fiberglass batt insulation consists of lightweight glass fibers arranged into “batts” or blankets. It is one of the most affordable and commonly used types of insulation. Fiberglass contains an inner layer of plastic or foil vapor barrier on one side to prevent moisture buildup.


  • Inexpensive
  • Easy to install for DIYers
  • Widely available


  • Can sag over time
  • Fibers may cause skin irritation
  • Not as effective for soundproofing

Fiberglass works best for standard wall and ceiling cavities. It provides good insulation value for the price but requires proper installation to prevent air gaps.

Spray Foam Insulation

Spray foam insulation is applied by professional installers as a liquid that expands to fill cracks and voids. It then hardens into a solid foam. The two main types used in homes are open-cell and closed-cell foam.


  • Expands to fill gaps, preventing air leaks
  • Acts as a vapor barrier
  • Offers structural stability
  • Noise reduction abilities


  • More expensive than other types
  • Should be professionally installed
  • Can be messy if sprayed incorrectly

Spray foam is ideal for weatherizing drafty garages because it air seals and insulates in one product. It works well for unfinished walls, ceilings, floors, and in hard to insulate areas.

Rigid Foam Board Insulation

Rigid foam board insulation comes in large sheets usually made of expanded polystyrene (EPS), extruded polystyrene (XPS), or polyisocyanurate. The sheets are lightweight and can be cut to size.


  • High insulation value for its thickness
  • Moisture resistant properties
  • Easy installation for DIYers


  • More expensive than batts per square foot
  • Can be damaged by excess moisture
  • May require additional structural bracing

Foam boards work well for garage doors, walls, ceilings, and as a vapor barrier. They provide great insulation for the thickness and have high compressive strength.

Reflective Insulation

Reflective insulation uses sheets of aluminum foil with insulating air spaces in between. The foil reflects radiant heat rather than absorbing it.


  • Thin profile for cramped spaces
  • Effective at reducing radiant heat flow
  • Low cost


  • Not intended for cold climates
  • Requires an air gap to work properly
  • Tears easily during installation

Radiant barrier reflective insulation works best for hot, sunny climates. It is not meant to provide complete insulation but helps reduce summer heat gain. It should be combined with other insulation materials.

Cellulose Loose-Fill Insulation

Cellulose is made from recycled materials like newspaper or wood fibers. It is blown into wall cavities as loose-fill insulation using special equipment.


  • Made from recycled materials
  • Treatment resists moisture damage
  • Fills cracks and voids thoroughly
  • Offers good noise reduction


  • Settling can occur over time
  • Blowing machine required for installation
  • Potential for moisture issues in some climates

Loose-fill cellulose is great for retrofitting existing garages by dense packing wall cavities. It requires professional installation but offers excellent coverage around electrical, plumbing, and other obstructions.

Key Factors to Consider

When selecting garage insulation, key factors to consider include:

  • Climate – The optimal insulation depends on your climate zone’s temperatures and humidity levels. In hot climates, radiant barriers help, while cold climates need products with higher R-values.
  • Space Usage – Will the garage be conditioned living space or used for storage/work? This affects the necessary insulation levels.
  • Moisture Control – Preventing condensation buildup is crucial in garages. Some insulations function better as vapor barriers.
  • Budget – Foam and blown-in types cost more installed but may provide energy savings long-term. Batts are budget-friendly.
  • Air Sealing – Make sure to seal all cracks, gaps, and penetrations first so insulation works effectively.

Frequently Asked Questions

Below are some common questions about garage insulation:

What R-value is recommended for garage insulation?

For most garages, an insulation R-value between R-13 and R-30 is recommended depending on climate and usage. High traffic garages may need a rating of R-30 or more.

Should garage ceilings be insulated?

Yes, insulating garage ceilings is highly recommended, as heat rises and can escape through the roof. Use at least R-30 batts or blown-in insulation in the ceilings for proper coverage.

Is it worthwhile to insulate garage doors?

Insulating garage doors improves energy efficiency and makes the space more comfortable. Options like polyurethane foam kits help prevent conduction through the panels and seals the gaps.

Can you install insulation in finished garage walls?

Finished garage walls can be insulated by removing the drywall and blowing dense-pack cellulose before reinstalling. You can also add rigid foam boards to the interior framed walls before drywall.

What type of insulation works best for soundproofing?

Certain insulations like spray foam, rigid boards, and dense-pack cellulose provide extra noise reduction abilities. Adding layers of different materials helps dampen sounds most effectively.

Does garage insulation need a vapor barrier?

In most climates, having a vapor barrier on the warm-in-winter side of the insulation helps prevent moisture issues like mold or mildew. Kraft or foil-faced batts, rigid foam, and spray foam provide built-in vapor barriers.


Adding proper insulation transforms garages from merely car storage to functional, comfortable workshop space. Fiberglass batts provide affordable basic coverage, while spray foam air seals and insulates irregularly shaped areas. Rigid foam boards work well for garage doors and finished walls. Reflective insulation reduces heat gain in hot climates. Cellulose loose-fill insulation is great for retrofits. Consider factors like climate, budget, and noise control when selecting the right garage insulation. With the proper installation of one of these 5 types, your garage can become a properly insulated and conditioned space.