Use this construction calculation for preliminary quantity, geometry, material, load, or coverage planning when dimensions and units have been measured consistently.

Layer R-values (m²·K/W)

Required list input.

Sum thermal resistance values of layers in series; use the same R-value unit for every layer. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Total thermal resistance (m²·K/W)

The resulting total thermal resistance returned as a number.

• Nominal R- and U-values do not by themselves capture thermal bridges, air leakage, moisture, compression, installation gaps, surface films, aging, or whole-assembly performance. Energy-code compliance requires the prescribed assembly method.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Verify dimensions on site, use current product data and local code requirements, include an explicit waste or safety allowance where appropriate, and obtain qualified structural, electrical, plumbing, or geotechnical review when required.

• Insulation Thickness From Rvalue

  Homogeneous insulation thickness from target area-specific R-value and material thermal conductivity in SI units.

• Hunter Fixture Units

  Sum fixture-unit loads from parallel fixture counts and assigned units per fixture; this is not the Hunter demand-curve conversion to flow.

• Insulation Compression Factor

  Geometric thickness-retention fraction of insulation after compression; it is not a direct R-value correction.