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.

Insulating a roof without ventilation.

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. For the same reason insulation shouldn t touch the roof s underside. Insulate below the roof the most conventional approach to insulating a roof is to put all the insulation below the roof deck. For homes without soffits or narrow ones the attic can still be very effectively insulated.

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. This approach is especially prevalent in retrofits when the existing roof is in good shape but the attic is being conditioned. This moisture is released into the air inside the house from bathing cooking plants laundry and other causes. Sealing bypasses bypasses are anywhere that there is a break in the insulation.

However these scenarios require another solution to address ventilation. The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow. Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation. 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.

Without adequate ventilation moisture rises with the hot air and forms condensation on the inside of the roof deck. 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. With flat roof insulation a vapor barrier should sit between the joists and ceiling panels and the insulation on top.