Linear accelerator vaults and vault doors often require a significant thickness of lead. Generally the requirement for lead up to and including 3/4″ (19.04mm equivalency) is accomplished using sheet lead. The switch to brick usually starts when the requirement is 1″ (25.4mm) or greater although in some cases 1″ sheet lead backed on plywood can be used. a-fabco, inc. sells interlocking lead bricks that measure 4″ x 12″ and vary in weight according to the thickness. Lead requirements in excess of 2-1/2″ in thickness are achieved by stacking multiple layers one in front of the other as pictured right. The brick is tied to the wall and steel vertical structure built in front of the wall after the brick section is completed.
Neutron swinging and sliding doors also require lead, usually brick which is custom fit and cut before the door is shipped. The bricks are numbered after fitting, removed from the door and stacked on pallets for shipping to the job site. The door is re-loaded after it is hung on the job site.