Why Not Put Insulation Under The Roof

Even if you use vent chutes to provide an air space above the insulation you can still have problems.

Why not put insulation under the roof.

The percentage of your home s heat that is lost through the roof is on average around 40 percent. Moisture goes right through fiberglass and will condense on the cold underside of your roof. Staple plastic or foam baffles to the roof sheathing near the eaves to keep the material away. A roof without good insulation is a great contributor to energy loss.

A roof does get hotter than the walls in the summer but doesn t matter at least in colder climates. Thus the air in the attic is connected with the air in the house. Proper insulation can significantly reduce your energy consumption heat in the winter ac in the summer and reduce your energy costs by hundreds of dollars a year. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense.

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. 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 moisture is held in place by the insulation which allows for damage to the framing and other building components.

If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value. 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. 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. But a common reason to put spray foam on the roofline is to avoid having to air seal the attic floor.

Moreover you lose less space. 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 you leave the insulation in the attic floor after insulating the roofline the attic will be cooler in winter than if you remove the insulation. So in choosing insulation for a cathedral ceiling you really want a material that stops air and moisture from reaching that sensitive roof deck.

If the cavity between the rafters trusses is filled with insulation and is air tight like the walls you will need a vapour barrier. The problem with the insulation against the sheathing expands. The material is compressible and is thus easy to fit and is less likely to cause cracks.