The term "R value" typically refers to the thermal resistance of insulation material, which is a measure of its ability to resist heat transfer. The depth of a foundation is important to ensure that it is able to support the weight of the structure and resist movement due to soil settlement or freeze/thaw cycles which can cause immense hydrostatic pressure.

What is thermal resistance of insulation?

Thermal resistance is the ability of a material to resist the flow of heat through it. In the context of insulation, thermal resistance is an important property as it determines the effectiveness of the insulation in reducing heat transfer through the building envelope.

The thermal resistance of insulation is measured in R-value, which is a unit of thermal resistance. The higher the R-value, the better the insulation's ability to resist heat transfer. For example, an insulation material with an R-value of 10 is more effective at reducing heat transfer than a material with an R-value of 5.

Insulation works by reducing the rate of heat flow through the building envelope. This helps to maintain a comfortable indoor temperature and reduces the amount of energy needed to heat or cool a building. Insulation materials can vary in their thermal resistance, and the appropriate R-value for a particular application depends on factors such as the local climate, building design, and energy efficiency goals.

It's important to note that thermal resistance is just one of the factors that determine the effectiveness of insulation. Other factors such as air infiltration, moisture management, and installation quality also play a role in the overall performance of insulation in a building.