About insulation
laufer
| Posted in Energy Efficiency and Durability on
I am building a one-story house in Ghana with an aluminium roof.
I want to insulate this house in order to prevent the heat outside from coming inside.
I intend to install a plasterboard ceiling.
My question is: Should I install the insulation under the roofing sheets or above the ceiling?
Thanks.
Amnon Laufer
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Replies
Amnon,
Either way will work, but it's usually easier to insulate above the plasterboard ceiling rather than along the sloping roof.
However, the answer depends in part on (a) what type of insulation materials are available in Ghana, and (b) whether you will be using the space above the plasterboard (the attic) as living space.
With a shiny aluminum roof you will get more performance out of the insulation if there is at least 2" of air gap between the aluminum and insulation, with enough slope and ventilation area that the air in the gap will convect when the air heats up, pulling cooler outdoor air into the gap.
The low emissivity of the aluminum reduces the amount of heat transferred directly to the insulation layer to something much lower that if it were in direct contact with the insulation.