Insulating A Roof Without Ventilation

Without adequate ventilation moisture rises with the hot air and forms condensation on the inside of the roof deck.

Insulating a roof without ventilation. Cold roof to produce a cold roof the insulation has to be fitted inside below the weatherproofing support beams brickwork etc with a ventilated air gap. 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. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation. It could be said that this makes for an easier insulation project in the attic because there s no worry about inadvertently covering over soffit vents with insulation material.

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. For homes without soffits or narrow ones the attic can still be very effectively insulated. When the condensation forms on the roof deck it begins to rot the wood. This approach is especially prevalent in retrofits when the existing roof is in good shape but the attic is being conditioned.

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. Sealing bypasses bypasses are anywhere that there is a break in the insulation. However these scenarios require another solution to address ventilation. This moisture is released into the air inside the house from bathing cooking plants laundry and other causes.

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. For the same reason insulation shouldn t touch the roof s underside. With flat roof insulation a vapor barrier should sit between the joists and ceiling panels and the insulation on top.