Building designers have long been intrigued by the pleasing esthetic effects which can be achieved by combining glass brick and monolithic concrete. Successful application techniques have been developed with the result that almost any modern reinforced concrete building can be effectively illuminated with well- diffused, shadowless light without any recourse to conventional windows. The installation technique consists of first erecting the steel to the correct spacing. The reinforcement and the edges of the glass bricks are then brushed with a rich porland cement/silicate sand mortar of paint-like consistency. The basic mix is then firmly tamped and rodded in place. Each course of bricks is checked for accuracy of position after the basic mix has been tamped home. The final step is to steel trowel a finishing mortar into place flush with the bricks; for the inside of a roof this is done after the form has been stripped.