Roof Insulation No Ventilation

Under a flat or low slope roof the usual rules about roof insulation and ventilation don t apply.

Roof insulation no 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. If your attic is well insulated the insulation might be plugging the spaces between rafters just above exterior walls. 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. In cold climates snow can enter the soffit and ridge vents melt and potentially cause rot.

In an un vented roof foam can serve as the air barrier and vapor retarder and prevent moisture from getting in to the roof cavities. The roof cavity between rafters can be filled with insulation followed by installation of a perfect vapor barrier followed by finish surface of drywall or whatever else. This article explains methods for avoiding moisture condensation problems in compact insulated roofs that have no roof cavity space and in steel or wood framed roofs that have a roof cavity space and. The solution is to add baffles which allow air to flow past the insulation photo 9.

Unless your roofing system has insulation on the roofing deck and is designed without ventilation your furnace should not be heating your attic. For the same reason insulation shouldn t touch the roof s underside. Foam and the roof assembly foam insulation can play an important role in both vented and un vented roof assemblies. Poor insulation is usually the culprit although if you enter the attic on sunny winter day your attic space can be warmed by the sun more than your furnace.

Rafter vents or insulation baffles install in any rafter space to create narrow gaps that direct fresh air from the soffit vents to the peak of the roof. That means air can t flow from the soffit vents to the roof vents. In cases where there is no under roof venting system no soffit intake vents no ridge vents a hot roof design is followed. If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air.

If there s blown in insulation like ours rake back the fluffy stuff with a 3 or 4 ft long 1 x 6 or use a garden rake or hoe. Baffles are available at home centers. The answer is rafter venting. A properly functioning un vented roof.