retardant material such as a mineral fiber cushion or pillow such a mineral fiber cushion is normally encapsulated with polyethylene facing and preferably is affixed in any conventional means with respect to the downward protruding leg of the safing angle member 10 in this manner the construction of the safing angle member 10 and cover member 12 with the curtain blanket 14 retained therewithin and the safing gap insulation member 38 attached to the outer surface of the safing angle member 10 can be attached as a single unitary construction with respect to the curtain wall 24 prior to installation thereof which greatly facilitates such installation and minimizes labor costs it should be appreciated that an aesthetic cover may extend over the operating construction of this invention including extending over the safing angle member 10 and the cover member 12 to conceal the curtain during normal building operations it should be appreciated that when the construction of the present invention including the safing angle member 10 and the cover member 12 and the retained blanket 14 with the safing gap insulation member 38 secured to the safing angle member can be installed in a single step prior to installation of the curtain wall 24 and for this reason the flexibility of the safing gap insulation member 38 becomes very important this construction preferably will comprise a flexible mineral fiber cushion.