Insulating A Roof Without Ventilation

For homes without soffits or narrow ones the attic can still be very effectively insulated.

Insulating a roof without ventilation.

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. 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. Covering up the soffit vents with loose fill or batts which can happen if you stuff insulation along the eaves is a huge no no. Insulate below the roof the most conventional approach to insulating a roof is to put all the insulation below the roof deck.

However these scenarios require another solution to address ventilation. For the same reason insulation shouldn t touch the roof s underside. This approach is especially prevalent in retrofits when the existing roof is in good shape but the attic is being conditioned. Without adequate ventilation moisture rises with the hot air and forms condensation on the inside of the roof deck.

Sealing bypasses bypasses are anywhere that there is a break in the insulation. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation. In buildings where there is no roof venting anyway and where ventilation is difficult or impossible to achieve an un vented well insulated hot roof can provide a high r value ceiling and may be the second best alternative to preventing ice dam related leaks in cold climates. The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow.

This moisture is released into the air inside the house from bathing cooking plants laundry and other causes. When the condensation forms on the roof deck it begins to rot the wood. Construct a soffit or eaves overhang combined with assuring that an opening is provided all along the top of the building wall by removing any blocking between roof rafters at the top plate combined with use of roof insulation baffles to assure an air inflow pathway under the roof deck.