There are several advantages to installing roof insulation in industrial and commercial buildings from above, rather than from below after the roof is sealed. A reinforced facing sheet is used that can be rolled out between the purlins that support the steel roofing. This reinforced facing material is located at the bottom of an insulation system and is used to support the insulation from below. The reinforced facing sheet must be anchored to reduce pillowing of the insulation and provide a neat appearance to the insulation job. The anchoring system for the reinforced facing material is made up of a metal angle that is firmly affixed to the top of a rafter between purlins. The reinforced facing material is, thus, sandwiched between the angle and the rafter top, and securely anchored, there. A channel-shaped lower support member, usually vinyl, is located beneath the reinforced facing material and the angle is pressed, from above, into the open part of the channel shape as it is situated on top if the rafter. Consequently, the reinforced facing material is also pressed into the lower support member, thus holding the reinforced facing material at the correct elevation.