What material is commonly used for perimeter insulation of a concrete slab floor?

Polystyrene is commonly used for perimeter insulation of a concrete slab floor due to its excellent thermal insulating properties, moisture resistance, and lightweight nature. This material is effective in preventing heat loss from the edges of the slab, which can be significant as concrete conducts heat well. The rigidity of polystyrene also provides structural support, ensuring that it maintains its shape and effectiveness over time.

In the context of insulation types, polystyrene offers superior R-value, which is a measure of thermal resistance, making it an ideal choice for building applications where energy efficiency is a priority. It is also available in various forms, including expanded and extruded polystyrene, each providing effective thermal performance either above or below ground.

Other options, such as fiberglass, while used in various insulation scenarios, do not provide the same moisture resistance and structural support as polystyrene. Polyurethane can also be effective but is generally more expensive and not as commonly used for perimeter insulation in concrete applications. Cellulose, primarily made from recycled paper products, serves well in insulating walls and attics but is less effective for the specific requirements of perimeter insulation with regard to moisture and durability in this particular context.