Key words Functional problems, extremal solutions, Greens functions, lower and upper solutions MSC (2010) 34B15, 34B10, 34K10In this paper, given f :is considered the functional fourth order equationtogether with the nonlinear functional boundary conditionsHere L i , i = 0, 1, 2, 3, satisfy some adequate monotonicity assumptions and are not necessarily continuous functions. It will be proved an existence and location result in presence of non ordered lower and upper solutions.