A door wall is a sliding-glass door or patio door. The term is yet another example of banal Michigan vernacular, where in the residents latch on to company names, trademark names, marketing terms and product names from
local companies. The terms become embedded in the local vocabulary and eventually become accepted as actual valid
words and phrases. In this case the term comes from Wallside
Windows in Taylor, MI (a large window manufacturer), where 'door wall' is their created word for sliding-glass door.