Cantilever or Exposed Floors

The advantages and disadvantages of various options to consider

Fill entire floor joist cavity with fiberglass batt insulation

Advantages

• Easy and inexpensive to build

Disadvantages

• Cool floor to walk on
• No opportunity to run ductwork to a floor grill next to the exterior wall
• Needs special attention to properly seal the AVB at the floor joist header area

Partly fill floor joist cavity with fiberglass batt insulation and make up for shortfall by adding a layer of rigid insulation below

Advantages

• Warm floor to walk on
• Allows for a duct run to a floor grill next to the exterior wall

Disadvantages

• Takes a little more time, attention and cost to get AVB installation details correct

Use rigid insulation between and below floor joists

Advantages

• Warm floor to walk on
• Allows for easy duct run to a floor grill next to the exterior wall
• Easier to install proper AVB

Disadvantages

• Takes a little more time, attention and cost for proper installation

Expanding spray foam insulation

Advantages

• Easy to get a good AVB
• Allows for a potential duct run to a floor grill next to the exterior wall
• Warmer floor surface to walk on

Disadvantages

• More expensive
• Involves an additional trade