Understanding Ceiling Insulation

Author: Brian February 5, 2014

I frequently see comments like “Ceiling insulation is next to worthless in summer.”

I have even heard people say “With a hot roof space it will be overwhelmed.” and “After the sun has gone off it stops the house cooling down.”

Here is the truth:

• All insulation works by slowing the rate of heat transfer. If the roof space is hot some heat will pass through to the room below. The insulation will slow the rate that the room heats up from the roof space.
• Ceiling insulation isn’t enough to keep the room cool by itself. The room will still get hotter if heat is leaking in through poorly insulated walls and windows.
• Ceiling insulation, by slowing the heat gain from the roof space, will reduce the cost of mechanical cooling.
• In a well insulated conventional ceiling minimal residual heat remains in the plasterboard and ceiling insulation. The heat in the room is just hot air. The best way to remove the hot air is to open the windows when the air temperature outside is less than inside, or run the air conditioning.

See Insulation Basics – Ceiling Insulation to see the difference it makes.