Building Material R-values

Building material R-values for layer calculators

Wood, brick, concrete, gypsum board, plywood, OSB, and air spaces use broad typical ranges. Use the page for wood, brick, concrete, gypsum board, plywood, OSB, and air spaces when you need a starting value for a layer model.

Building material reference values

Wood, brick, concrete, gypsum board, plywood, OSB, and air spaces use broad typical ranges. Use the page for wood, brick, concrete, gypsum board, plywood, OSB, and air spaces when you need a starting value for a layer model.

Assembly thickness

Thickness examples: 12 mm OSB layer: 0.47 in * about R-0.7 per in = about R-0.33; 100 mm concrete layer: 0.100 m / 2.3 W/mK = RSI 0.04; 13 mm gypsum board: 0.51 in * about R-0.9 per in = about R-0.46.

U-value

Higher R per inch can reduce required thickness, but the final U-value still depends on every layer, surface resistance, and thermal bridging.

MaterialBuilding material reference values
CategoryMass materials and air spaces
LambdaWood, brick, concrete, gypsum board, plywood, OSB, and air spaces use broad typical ranges
ThicknessThickness examples: 12 mm OSB layer: 0.47 in * about R-0.7 per in = about R-0.33; 100 mm concrete layer: 0.100 m / 2.3 W/mK = RSI 0.04; 13 mm gypsum board: 0.51 in * about R-0.9 per in = about R-0.46.

Use the page for wood, brick, concrete, gypsum board, plywood, OSB, and air spaces when you need a starting value for a layer model.

Ranges depend on density, moisture, direction, cavity orientation, foil surfaces, and whether the value is per inch or for a fixed layer thickness.

This reference supports wall, roof, and floor layer calculators with broad R-value ranges for common building materials. It is not insulation advice: dense materials usually add small R-value compared with dedicated insulation.

Thickness examples: 12 mm OSB layer: 0.47 in * about R-0.7 per in = about R-0.33; 100 mm concrete layer: 0.100 m / 2.3 W/mK = RSI 0.04; 13 mm gypsum board: 0.51 in * about R-0.9 per in = about R-0.46.

Typical values are planning ranges. Check the declared product value, local code, and the complete assembly before construction.

Practical note

How to interpret lambda for Building material reference values

Building material reference values 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 “Mass materials and air spaces”, and the reference value is shown as Lambda Wood, brick, concrete, gypsum board, plywood, OSB, and air spaces use broad typical ranges. 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.

Material selector data

These ranges feed the calculator material lists. Treat them as typical ranges and verify product declarations.

IdMaterialR per inchλ rangeNotePage
fiberglassFiberglass battR 3.0-3.8/in0.038-0.046 W/mKLightweight option for walls and attics; verify the product declaration.Open
mineral-woolMineral woolR 3.7-4.3/in0.034-0.041 W/mKNon-combustible layer for walls, roofs, and acoustic assemblies.Open
epsEPS foamR 3.6-4.2/in0.034-0.040 W/mKRigid board for floors, walls, and exterior systems.Open
xpsXPS foamR 4.5-5.0/in0.029-0.034 W/mKRigid board with good moisture and compressive resistance.Open
polyisoPolyiso boardR 5.6-6.5/in0.020-0.026 W/mKHigh R per inch at lower thickness; facers change declared values.Open

Assumptions and sources

Material values are typical ranges for early comparison. Real values depend on the product, density, moisture, installation, and manufacturer declaration.

Review: 2026-04-27
  • Check the product datasheet before selecting a final lambda or R per inch value.
  • Local codes, thermal bridges, and air layers can change the required result.
  • For permit or design work, have the assembly reviewed by a qualified professional.
  • Last range review: 2026-04-27.

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Editorial review

Reviewed by the LambdaCalculator editorial team.

Last reviewed:

This page is for educational thermal calculation support.

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Calculator integration

Thickness examples: 12 mm OSB layer: 0.47 in * about R-0.7 per in = about R-0.33; 100 mm concrete layer: 0.100 m / 2.3 W/mK = RSI 0.04; 13 mm gypsum board: 0.51 in * about R-0.9 per in = about R-0.46. Higher R per inch can reduce required thickness, but the final U-value still depends on every layer, surface resistance, and thermal bridging.

Material-specific check

Use the page for wood, brick, concrete, gypsum board, plywood, OSB, and air spaces when you need a starting value for a layer model.

Planning limitation

Ranges depend on density, moisture, direction, cavity orientation, foil surfaces, and whether the value is per inch or for a fixed layer thickness.

Worked example 1: 12 mm OSB layer

0.47 in * about R-0.7 per in = about R-0.33. Treat this as a planning result, then confirm the exact product label and installed thickness.

Worked example 2: 100 mm concrete layer

0.100 m / 2.3 W/mK = RSI 0.04. Treat this as a planning result, then confirm the exact product label and installed thickness.

Worked example 3: 13 mm gypsum board

0.51 in * about R-0.9 per in = about R-0.46. Treat this as a planning result, then confirm the exact product label and installed thickness.

Forms and use cases

Use the page for wood, brick, concrete, gypsum board, plywood, OSB, and air spaces when you need a starting value for a layer model.

Limits to check

Ranges depend on density, moisture, direction, cavity orientation, foil surfaces, and whether the value is per inch or for a fixed layer thickness.

Quick answer

This reference supports wall, roof, and floor layer calculators with broad R-value ranges for common building materials. It is not insulation advice: dense materials usually add small R-value compared with dedicated insulation. Wood, brick, concrete, gypsum board, plywood, OSB, and air spaces use broad typical ranges.

Material R-value FAQ

Use Wood, brick, concrete, gypsum board, plywood, OSB, and air spaces use broad typical ranges for early comparison, then replace it with the declared value for the exact product.

Use the page for wood, brick, concrete, gypsum board, plywood, OSB, and air spaces when you need a starting value for a layer model.

Ranges depend on density, moisture, direction, cavity orientation, foil surfaces, and whether the value is per inch or for a fixed layer thickness.

Yes. You can print the result or export it to CSV, Excel, or PDF for reports and documentation.

Yes. It is designed for layered assemblies such as external walls, flat roofs, pitched roofs, floors, and slabs. For unusual assemblies, add every relevant layer and treat the result as a planning check before formal verification.

Yes. It is intended for fast concept-stage calculations, insulation comparison, and envelope optimisation before detailed design. It is best used to narrow choices, not to replace a code check or project-specific thermal bridge assessment.

Yes. You can switch between millimeters, centimeters, and inches, and the calculator keeps the values consistent. For fewer mistakes, choose one unit system at the start of a project and review converted thicknesses before export.

Use Building material R-values for layer calculators as a first-pass reference. Before specifying anything, compare the result with the material availability, actual project dimensions, product data sheet, and local requirements.