- design block patterns and system components considerate of national concrete masonry association tek3-16a
the blocks : trestles blocks are special screen block units with decorative openings. they can be used in both interior and exterior environments in applications such as sunscreens, room dividers, fences and curtain walls. often used in non-loadbearing structures, the blocks are designed to astm c90 standards for load-bearing concrete masonry units; though special detailing of system components should be considered for loadbearing applications. refer to ncma tek3-16a for details in designing the vertical and horizontal spans of the walls.