What is the minimum recommended depth of air space for reflective insulation to be effective?

The minimum recommended depth of air space for reflective insulation to be effective is 3/4 inch. This depth is crucial because reflective insulation relies on the still air layer created within the space to function properly. The air acts as an insulator, reducing heat transfer by conduction and convection. If the air space is too shallow, the insulation will not perform optimally, as it needs a specific thickness to create a significant barrier against radiant heat.

When the air gap is at least 3/4 inch, it allows for effective thermal performance and ensures that the reflective surface can properly reflect radiant heat away from the conditioned space, enhancing overall energy efficiency and comfort. Depths shorter than this may fail to create the ideal conditions for effective reflection and insulation.