Home Retaining Wall R-value Calculator

Please select the floor type:
Suspended timber or concrete floor
Slab on ground floor
Retaining walls

The retaining wall R-value consists of the R-value of the wall itself and the R-value of the ground behind the retaining wall.

The calculator on this page calculates the R-value of the ground behind the wall. To calculate the R-value of the complete wall select "complete wall insulation" in the "Insulation" drop-down box below. Then in the "Insulation R-value" cell enter any additional R-values such as the R-value of the wall structure itself (concrete, insulation, strapping, etc.). This "Insulation R-value" includes everything which is in addition to the ground itself.

What to enter in the "Insulation R-value" cell:

  • If you want to be "super-accurate" you could enter R-0.06 for a 100mm concrete wall or R-0.14 for 200mm concrete blocks although these values are well within the limits of accuracy of this calculator and also of any other slab floor and retaining wall calculations such as NZS4214.
  • If you have a complete layer of polystyrene as insulation you can simply enter that R-value in the "Insulation R-value" cell.
  • If you have a wall with strapping, insulation and lining you would first calculate the R-value of those components using the Floor, Wall and Roof R-value Calculator page and then enter that construction R-value in the "Insulation R-value" cell below.

This calculator simply adds the retaining ground R-value and the "Insulation R-value" together.

Note: The actual retaining wall heat losses are very complex. This calculator provides an approximate value only.

Retaining wall area [m]
Retaining wall length [m]
External wall thickness [mm] (defaulted to 200mm for retaining walls. That represents the typical retaining wall thickness.)
Soil conductivity [W/m C]


The specified retaining wall has an R-value of m C/W.