Open-cell R-3.5 to R-3.8 per inch; closed-cell R-6.0 to R-7.0 per inch. Open-cell foam is usually discussed for air sealing and cavity fill; closed-cell foam is discussed where higher R per inch, vapor control, or strength may matter.
Open-cell R-3.5 to R-3.8 per inch; closed-cell R-6.0 to R-7.0 per inch. Open-cell foam is usually discussed for air sealing and cavity fill; closed-cell foam is discussed where higher R per inch, vapor control, or strength may matter.
Thickness examples: 3 inch open-cell layer: 3 in * R-3.7 per in = R-11.1; 2 inch closed-cell layer: 2 in * R-6.5 per in = R-13.0; R-19 closed-cell target: R-19 / R-6.5 per in = 2.9 in.
Higher R per inch can reduce required thickness, but the final U-value still depends on every layer, surface resistance, and thermal bridging.
| Material | Spray foam insulation |
|---|---|
| Category | Open-cell and closed-cell spray foam |
| Lambda | Open-cell R-3.5 to R-3.8 per inch; closed-cell R-6.0 to R-7.0 per inch |
| Thickness | Thickness examples: 3 inch open-cell layer: 3 in * R-3.7 per in = R-11.1; 2 inch closed-cell layer: 2 in * R-6.5 per in = R-13.0; R-19 closed-cell target: R-19 / R-6.5 per in = 2.9 in. |
Open-cell foam is usually discussed for air sealing and cavity fill; closed-cell foam is discussed where higher R per inch, vapor control, or strength may matter.
Do not treat spray foam as a casual DIY choice. Fire protection, ventilation, substrate condition, curing, code requirements, and installer competence are critical.
Spray foam has two very different R-value ranges: open-cell foam is commonly around R-3.5 to R-3.8 per inch, while closed-cell foam is often around R-6.0 to R-7.0 per inch. Air sealing and professional installation are part of the decision.
Thickness examples: 3 inch open-cell layer: 3 in * R-3.7 per in = R-11.1; 2 inch closed-cell layer: 2 in * R-6.5 per in = R-13.0; R-19 closed-cell target: R-19 / R-6.5 per in = 2.9 in.
Typical values are planning ranges. Check the declared product value, local code, and the complete assembly before construction.
Spray foam insulation should be assessed through declared lambda, layer thickness, and the conditions it will see inside the assembly. In this database the material is grouped as “Open-cell and closed-cell spray foam”, and the reference value is shown as Lambda Open-cell R-3.5 to R-3.8 per inch; closed-cell R-6.0 to R-7.0 per inch. Use it as a comparison value, not as a guarantee for every product sold under a similar name.
Real insulation performance depends on density, moisture, temperature, ageing, compression, and installation quality. Two products with similar commercial names can have different declared values, so current technical data sheets should be checked before purchase or specification.
In a simple calculation, layer resistance is thickness in metres divided by lambda. If a layer is 100 mm and lambda is 0.040 W/mK, resistance is about 2.50 m²K/W. A complete U-value still needs the other layers, surface resistances, and thermal bridge review.
Do not compare the material by lambda alone. Moisture resistance, compressive strength, fire behaviour, acoustic goals, compatibility with adhesives or membranes, and the ability to form a continuous layer can all change the best choice. For final decisions, use current manufacturer data and local requirements.
When comparing materials, check whether the value is a declared design value, a laboratory value, or a calculation value. Different sources may show different numbers for the same product family, especially when density, moisture, or application changes.
A material with a strong lambda value does not guarantee a strong U-value if it is installed too thinly or with thermal bridges. After reading the value, test the full layer build-up in the calculator.
These ranges feed the calculator material lists. Treat them as typical ranges and verify product declarations.
| Id | Material | R per inch | λ range | Note | Page |
|---|---|---|---|---|---|
fiberglass | Fiberglass batt | R 3.0-3.8/in | 0.038-0.046 W/mK | Lightweight option for walls and attics; verify the product declaration. | Open |
mineral-wool | Mineral wool | R 3.7-4.3/in | 0.034-0.041 W/mK | Non-combustible layer for walls, roofs, and acoustic assemblies. | Open |
eps | EPS foam | R 3.6-4.2/in | 0.034-0.040 W/mK | Rigid board for floors, walls, and exterior systems. | Open |
xps | XPS foam | R 4.5-5.0/in | 0.029-0.034 W/mK | Rigid board with good moisture and compressive resistance. | Open |
polyiso | Polyiso board | R 5.6-6.5/in | 0.020-0.026 W/mK | High R per inch at lower thickness; facers change declared values. | Open |
Material values are typical ranges for early comparison. Real values depend on the product, density, moisture, installation, and manufacturer declaration.
See how formulas, unit conversions, rounding, and limitations are handled. Methodology details.
Move between R-value calculators, material tables, insulation comparisons, and assembly calculators without scanning the whole navigation.
Thickness examples: 3 inch open-cell layer: 3 in * R-3.7 per in = R-11.1; 2 inch closed-cell layer: 2 in * R-6.5 per in = R-13.0; R-19 closed-cell target: R-19 / R-6.5 per in = 2.9 in. Higher R per inch can reduce required thickness, but the final U-value still depends on every layer, surface resistance, and thermal bridging.
Open-cell foam is usually discussed for air sealing and cavity fill; closed-cell foam is discussed where higher R per inch, vapor control, or strength may matter.
Do not treat spray foam as a casual DIY choice. Fire protection, ventilation, substrate condition, curing, code requirements, and installer competence are critical.
3 in * R-3.7 per in = R-11.1. Treat this as a planning result, then confirm the exact product label and installed thickness.
2 in * R-6.5 per in = R-13.0. Treat this as a planning result, then confirm the exact product label and installed thickness.
R-19 / R-6.5 per in = 2.9 in. Treat this as a planning result, then confirm the exact product label and installed thickness.
Open-cell foam is usually discussed for air sealing and cavity fill; closed-cell foam is discussed where higher R per inch, vapor control, or strength may matter.
Do not treat spray foam as a casual DIY choice. Fire protection, ventilation, substrate condition, curing, code requirements, and installer competence are critical.
Spray foam has two very different R-value ranges: open-cell foam is commonly around R-3.5 to R-3.8 per inch, while closed-cell foam is often around R-6.0 to R-7.0 per inch. Air sealing and professional installation are part of the decision. Open-cell R-3.5 to R-3.8 per inch; closed-cell R-6.0 to R-7.0 per inch.