Ceiling - Obtain a ruler and go through the manhole of your ceiling to look at the ceiling insulation. Even if your insulation looks tidy, look carefully for small gaps and disturbed insulation that looks out of position.
Signs that you need more ceiling insulation include:
• Gaps in insulation
• Insulation not pushed right out to the top plates of the external walls
• Insulation not lofted above ceiling joists by 50mm or more
Wall - You can check wall insulation in several ways:
• Remove roof tiles over the external wall cavity and look inside the cavity
• Climb under a brick veneer house (if not on a concrete slab) and look up the cavity
• Have your electrician remove a power point or light switch on 1-2 outer walls so you can see inside the cavity.
• Have an insulation professional use a thermal imaging camera
• If your house is pre-2000, be prepared for the likelihood that it has no wall insulation at all.
Floor - Put your head under the floor through the manhole entrance and look for insulation. If your head can’t fit under the house, you can’t insulate it anyway, so don’t worry.