Reinforcement Detail of a Downstand Concrete Beam-Lintel for Door Window Opening Reinforcement Detail of a Downstand Concrete Beam-Lintel for Door Window Opening. Instead of using brick or gypsum board lintel fillings on top of a door or window opening, it is a good practice to reinforce and construct those lintels with reinforced concrete to prevent future hairline cracks at the discontinued wall opening. This CAD dwg drawing detail contains : lintel downstand reinforcement slab & beam reinforcement detailing minimum reinforcement requirements according to Eurocode 2 ( EC2 ) CAD .dwg file CAD .dxf file PDF unlimited use, unlocked, fully customisable Click on the Video Tab to view product in greater detail.