Calculate your energy savings and ROI with EPS, XPS, or Polyiso foam board insulation for construction and home improvement projects.
Choose from attic, wall, basement, or crawl space or use Quick Examples above
Input the square footage or dimensions of your space
Pick from EPS, XPS, Polyiso foam board, spray foam, or fiberglass
Enter current and desired R-values based on your climate zone
Get instant recommendations for thickness, cost estimates, and energy savings
Building & Construction Use Only: This calculator is for foam board insulation used in construction, home improvement, and building applications (walls, roofs, foundations). All materials shown are legal for construction use nationwide.
Quick Examples:
Typical room, wall, or basement area
Typical uninsulated: R-4 to R-11
Recommended: R-30 to R-49 for attics, R-13 to R-21 for walls
Check your utility bill for exact rate
For climate-specific calculations
138 lbs
CO₂ Emissions Reduced Annually
Equivalent to planting approximately 3 trees per year
EPS Foam Board (Expanded Polystyrene)
All foam boards are approved for building and construction use nationwide
Lower energy bills year-round with proper insulation installation
Reduce your carbon footprint and support sustainable building practices
Foam board insulation is one of the most effective and versatile forms of insulation available for residential and commercial construction projects. Made from expanded polystyrene (EPS), extruded polystyrene (XPS), or polyisocyanurate (polyiso), these rigid foam panels provide superior thermal resistance with minimal thickness, making them ideal for walls, roofs, foundations, and basements.
The R-value of insulation measures its thermal resistance - the higher the R-value, the better the material's ability to resist heat flow. Properly installed foam board insulation can significantly reduce heating and cooling costs by preventing heat transfer through conduction, convection, and radiation. This makes it an excellent choice for homeowners and contractors looking to improve energy efficiency and reduce carbon footprint.
Expanded Polystyrene (EPS) foam boards offer an excellent balance of performance and affordability. With an R-value of approximately 4.0 per inch, EPS is one of the most cost-effective insulation options. It's perfect for interior wall applications, basement walls, and crawl spaces. EPS is also moisture-resistant and provides good sound dampening properties.
Extruded Polystyrene (XPS) foam boards provide superior moisture resistance and thermal performance with an R-value of approximately 5.0 per inch. XPS is ideal for below-grade applications like foundation walls and basements where moisture control is critical. Its closed-cell structure makes it highly resistant to water absorption.
Polyisocyanurate (Polyiso) foam boards deliver the highest R-value at approximately 6.0 per inch, making them the most efficient option per inch of thickness. Polyiso is commonly used in commercial roofing applications and high-performance residential projects where space is limited but maximum insulation value is desired.
Properly installed foam board insulation can reduce heating and cooling costs by up to 40%. By creating an effective thermal barrier, insulation prevents conditioned air from escaping your home in winter and keeps cool air inside during summer months. This results in lower energy consumption and reduced utility bills year-round.
Reducing energy consumption through proper insulation directly decreases your carbon footprint. Less energy use means fewer greenhouse gas emissions from power plants. Additionally, many foam board products are made from recyclable materials, and some manufacturers produce foam boards with up to 20% recycled content.
Beyond energy savings, proper insulation creates more consistent indoor temperatures, eliminating cold spots and drafts. It also helps control moisture levels, reducing the likelihood of mold and mildew growth. This contributes to a healthier living environment and better overall comfort for occupants.
Foam board insulation typically pays for itself within 3-10 years through energy savings, depending on climate, fuel costs, and installation efficiency. After the payback period, homeowners continue to benefit from reduced energy costs for the life of the building. This makes insulation one of the best home improvement investments with both immediate and long-term financial returns.
For optimal performance, ensure foam boards are tightly fitted together with minimal gaps. Sealing joints with manufacturer-recommended tape or sealant prevents air infiltration. Install facing the correct direction - foil-faced boards should have the facing toward the conditioned space for best thermal performance. Always follow local building codes and manufacturer's installation guidelines.
When cutting foam boards, use proper tools like a utility knife or fine-toothed saw. Work in a well-ventilated area and wear appropriate safety equipment. Follow local fire codes regarding insulation flammability ratings. Some foam boards require thermal barriers (like drywall) when installed indoors. Always consult building codes and local regulations before installation.
Foam board insulation is remarkably durable and can last for the lifetime of the building when properly installed and protected from physical damage and moisture. Unlike other insulation types that may settle or degrade over time, foam boards maintain their R-value throughout their service life. Periodic inspection for damage or moisture issues is recommended to ensure continued performance.
EPS (Expanded Polystyrene) is made from expanded polystyrene beads and offers excellent thermal performance with R-values around 4.0 per inch. It's the most cost-effective option and suitable for most interior applications. XPS (Extruded Polystyrene) is produced through an extrusion process that creates smaller, more uniform cells, resulting in superior moisture resistance. It has an R-value of approximately 5.0 per inch and is ideal for below-grade applications where moisture is a concern. Polyiso (Polyisocyanurate) provides the highest R-value at around 6.0 per inch due to its advanced manufacturing process. It's often the preferred choice for commercial roofing and high-performance applications where space is limited but maximum efficiency is required.
The appropriate R-value depends on your climate zone, application area, and local building codes. Generally, attics require the highest R-values, with recommendations ranging from R-30 to R-60 depending on your climate. Exterior walls typically need R-13 to R-21 for 2x4 and 2x6 construction, respectively. Basements and crawl spaces should have at least R-10 for below-grade applications. Cold climates like northern states need higher R-values, while more moderate climates can use slightly lower values. Our calculator uses climate-specific heating and cooling degree days to provide accurate estimates based on your geographic location.
Yes, but different types of foam board have varying moisture resistance. XPS foam board is specifically designed for moisture-prone areas and features a closed-cell structure that resists water absorption. This makes it the preferred choice for foundation walls, basement applications, and below-grade installations. EPS foam board has some moisture resistance but should not be used in areas with standing water or continuous moisture exposure. Polyiso foam board can be used in controlled moisture environments but may require additional vapor barriers. Always ensure proper installation with sealed joints to prevent moisture infiltration regardless of the foam type used.
Foam board insulation contributes to environmental sustainability through its exceptional energy-saving properties. By reducing heating and cooling requirements, foam board insulation significantly decreases greenhouse gas emissions from power plants. Many foam board products contain recycled content, with some manufacturers incorporating up to 20% recycled materials in their production process. The long lifespan of foam board insulation, which can last for decades without degradation, means less material waste over time. Additionally, the energy savings realized over the life of the insulation far outweigh the manufacturing impact. When properly disposed of or recycled at end-of-life, foam board insulation can be an environmentally responsible building material choice.
Savings vary widely depending on factors such as your location, current insulation levels, home size, and local energy costs. Generally, properly installed foam board insulation can reduce heating and cooling costs by 20% to 40%. In a typical home with moderate insulation, homeowners can save $200 to $800 or more annually on energy bills. The payback period typically ranges from 3 to 10 years, after which the insulation continues to provide free savings for the life of the building. Our calculator provides customized estimates based on your specific project details, including climate adjustments and regional energy pricing.
R-value measures insulation's resistance to heat flow - the higher the R-value, the better the insulation performance. Different areas of your home require different R-values based on building codes and climate zone requirements.
R-38 to R-60 recommended depending on climate zone and local building codes.
R-13 to R-21 for standard 2x4 and 2x6 wall construction respectively.
R-10 to R-15 for below-grade applications with proper moisture barriers.
R-19 to R-25 recommended to prevent energy loss and moisture issues.
| Climate Zone | Attic | Walls | Floor | Basement |
|---|---|---|---|---|
| 1-2 | R-30 | R-13 | R-13 | R-0 |
| 3 | R-38 | R-20 | R-19 | R-5/10 |
| 4-5 | R-49 | R-20 | R-30 | R-10/15 |
| 6-8 | R-49 | R-21 | R-38 | R-15/20 |
Check local building codes as requirements may vary by jurisdiction and building type.
Insulation works most effectively when air leaks around windows, doors, and gaps are sealed to prevent heat loss.
Compressed insulation loses R-value effectiveness, reducing its thermal performance significantly.
Even small gaps in insulation coverage can reduce overall effectiveness by 25-40% in energy savings.
Prevents moisture problems in cold climates by blocking condensation within wall and floor assemblies.
Attic ventilation prevents moisture buildup and maintains consistent temperature throughout the space.
Helps reduce heat gain in hot climates, especially effective in Zone 1-3 regions with high cooling loads.
Important Notice: This calculator provides approximate estimates for building insulation projects only. Actual savings vary based on climate zone, installation quality, home construction, and local energy rates. For precise estimates, consult a certified energy auditor or licensed contractor. Material costs are approximate and may vary by region and supplier.
Last Updated: October 2025 | Based on current building codes and market prices