Why Not Put Insulation Under The Roof

Staple plastic or foam baffles to the roof sheathing near the eaves to keep the material away.

Why not put insulation under the roof.

The moisture is held in place by the insulation which allows for damage to the framing and other building components. This piece originally the quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies. This language is in both the residential and commercial codes. The problem with the insulation against the sheathing expands.

The percentage of your home s heat that is lost through the roof is on average around 40 percent. This is bad for the environment and for your wallet as you end up spending a lot more on your electric bills. For the same reason insulation shouldn t touch the roof s underside. The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow.

If the nasty old insulation was left on the floor of the attic the thermal envelope would be defined by that first layer of insulation so the roof deck insulation would be subject to much different temperature and humidity as allison stated in reason 1 above. This is an extremely large amount of heat that is exiting the building and leaving you and the other residents of the building feeling cold and vulnerable in the chillier months or climates. A roof without good insulation is a great contributor to energy loss. Moreover you lose less space.

The problem arises with moisture. Insulation should go up the side and over any tanks or special tank insulation can be used but you mustn t insulate under any tanks as without some heat flowing up from below these are also. If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value. Remember to fit a damp proof membrane if you go with mineral wool.

Consider an extreme example in which all of the attic floor insulation is piled up on half the area giving very very high r value there but none elsewhere. The material is compressible and is thus easy to fit and is less likely to cause cracks. Given a certain amount of insulation being used for a tight house uniform distribution throughout all parts of the shell exposed to the outside air in general does give minimum heat loss.