Is foam board better than fiberglass insulation?

Author: Keith Padberg  |  Last update: Sunday, January 18, 2026

High R-value: Because foam board insulation has a greater R-value than standard fiberglass/batt insulation, it is more effective at insulating and decreasing heat loss.

What are the cons of foam board insulation?

Insulation Foam Boards Don't Work On Uneven Walls

This allows moisture to seep in. Excess moisture can cause mold, mildew, odors, decay, fungus growth and wood rot.

What's better, foam board or fiberglass insulation?

Fiberglass insulation is notably less expensive than foam insulation. If your primary concern is the upfront cost, fiberglass may seem like an attractive option. However, it's crucial to consider long-term value. Foam insulation outshines fiberglass in terms of performance.

Is foam insulation better than fiberglass?

Yes, spray foam insulation provides a complete seal on cracks, gaps, voids, attics, walls, and crawl spaces, whereas fibreglass insulation provides extensive coverage but still leaves some cracks and gaps allowing air leakage.

Can I use foam board instead of insulation?

Yes - interior foam board is a well-tested method for improving thermal performance and comfort in a renovation.

Foam Insulation vs Fiberglass: The Ultimate Home Insulation Comparison Think Coffee Cups

Does foam board need a vapor barrier?

In general, if the foam rigid insulation is installed correctly and sealed properly, a vapour barrier may not be necessary. However, there are certain situations where a vapour barrier is recommended, such as in areas with high humidity levels or where there is a risk of moisture infiltration.

How much is foam board vs fiberglass?

Foam Board vs.

When calculated by R-value per square foot, fiberglass insulation costs less than half the price of rigid foam board insulation. For example, insulating a 10-square-foot wall area to R-15 costs about $3.40 to $4.00 with fiberglass insulation. A comparable R-value for rigid foam costs roughly $10.

Why not to use fiberglass insulation?

Fiberglass insulation is less dense than other types of insulation and does not create an airtight seal, which means air can travel freely through the insulation. This is called air leakage and it's one of the most common sources of energy loss in a house.

How thick should foam board insulation be?

How Thick Is Rigid Foam Insulation Board? Rigid board insulation generally comes in standard thicknesses ranging from ½ inch to 2 inches. It is possible for homes located in extreme climates to order specialty thicknesses of up to 6 inches directly from certain manufacturers.

Why is it hard to sell a house with spray foam insulation?

Some Buyers May Be Uncertain Of Spray Foam Insulation.

If they don't know the contractor who installed it, they may worry that the foam was installed by people who didn't know what they were doing. Other buyers have heard negative stories about spray foam insulation.

Is there anything better than fiberglass insulation?

In many ways, mineral wool is a superior insulation product. It has a higher R-value per inch compared to fiberglass, about a 22-37% higher R-value. It contains 70% recycled material, making it a greener product than fiberglass at 20-30% recycled material..

What is the most effective insulation board?

PIR insulation board, short for PolyIsocyanuRate (PIR), is one of the most capable and valuable heat resistant material used in UK constructions that can be used to insulate buildings for energy conservation.

What is the best insulation for exterior walls?

Foam Board or Rigid Foam

Foam boards -- rigid panels of insulation -- can be used to insulate almost any part of your home, from the roof down to the foundation. They are very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches.

Will mold grow on foam board?

Although its surface properties are not very conducive to the direct and rapid attachment of mold, if the environmental conditions continue to be unfavorable, mold may still find a foothold on polystyrene foam and gradually grow and spread.

What is the life expectancy of foam board insulation?

Foam board insulation, including types such as polystyrene, polyisocyanurate, and polyurethane, has a lifespan of 30 to 50 years. This type of insulation stands out for its moisture resistance and high thermal resistance, which contribute to its longevity and effectiveness in various applications.

Do I need house wrap if I use foam board?

House wrap helps prevent moisture damage, but when coupled with foam siding they create an unstoppable force. Moisture Management System for your home: It's estimated that each person uses 80-100 gallons of water per day at home. Instead of that moisture becoming trapped inside the home, foam can help it escape.

Does foam board insulation need an air gap?

Insulation boards are no exception to this rule, and it's important to leave an air gap between them and the surface they're installed on.

Why is foam board insulation so expensive?

Insulation costs vary depending on the materials used. For instance, foam board insulation tends to be pricier than fiberglass or cellulose because it offers a higher R-value and better moisture resistance, impacting both the product cost and the effectiveness in controlling temperature.

What is the safest insulation for a house?

The best non-toxic insulation is either mineral wool or foam insulation inserts.

Does fiberglass insulation need a 15 minute thermal barrier?

Pink Fiberglas™ Thermal Batt Insulation (Kraft Faced)

Kraft facing is a Class II vapor retarder. Cannot be left exposed — must be covered by a 15-minute thermal barrier.

Is yellow or pink insulation better?

In general, the color of insulation doesn't equal better performance over another color. Whether it's pink, white, brown, or yellow—color doesn't influence dependability, reliability, or the products effectiveness.

What are the negatives of foam board?

Cons of a Foamboard

Foamboards can get discolored, disintegrated or warped if left under the sun or rain. It can be used for a short outdoor event and not as a permanent outdoor display. Also keep it away from your bathroom or kitchen as steam can create moisture, affecting the foamboard.

What is a cheaper alternative to foam board?

Mineral-filled polypropylene is one of the least expensive styrofoam alternative options. In fact, it is the least expensive sustainable alternative.

How long does foam board last?

The lifespan of PVC foam board can vary depending on the quality of the material and the environment it is exposed to. High-quality PVC foam board that is properly installed or maintained can last up to 20 years or more in construction applications and up to 5 years or more in outdoor signage applications.

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