Insulation Blankets and Vapor Retarders for Metal Buildings

Insulation blankets are rolls of fiberglass or mineral wool installed beneath roof sheeting and behind wall sheeting. They reduce heat flow through the envelope, improve comfort, reduce energy use and help control noise from rain and the surroundings. In most metal buildings they are laminated to a facing that also acts as a vapor retarder.

Condensation is one of the most common problems in metal buildings. Warm, moist interior air meets the cold underside of the roof and forms droplets that drip, stain and corrode. A continuous vapor retarder on the warm side of the insulation, with sealed laps and edges, stops moist air reaching the cold surface.

Blanket thickness and density are chosen for the thermal performance required by the energy code or the owner. Facings are selected for vapor resistance, reflectivity, appearance and durability, and white facings are often used to brighten interiors. Where higher performance is needed, thermal spacer blocks or liner systems reduce the compression of insulation at purlins.

Installation quality matters as much as the product. Blankets are stretched across purlins before the sheeting is fixed, laps in the facing are sealed or stapled, and tears are repaired so the vapor retarder remains continuous.

World Steel supplies insulation and vapor retarders as part of the roof and wall system, with thicknesses and facings selected for each project. The project designer confirms the thermal and condensation requirements for the climate and building use.

A request for quotation should state the thermal performance target or energy code, interior humidity, building use, preferred facing and whether a liner is required. Where condensation risk is high, the vapor control strategy should be reviewed by the project designer.