On the basis of the second variant of Timoshenko theory the problem of deformation of longitudinal reinforced metal composite wall-beams is formulated in view of their weakened resistance to in-plane shear in conditions of the established creep. The mechanical behaviour of hinge supported and console beams are investigated. It has shown that application of classical Bernoulli theory to calculation of the established creep concerning the high reinforced wall-beams at a bending leads to a prediction of unreasonable understated compliance of thin-walled metal composite designs. The calculations have shown presence of significant rates of deformations of in-plane shears in binding material of such beams which account is obligatory and due to which there is basically an accumulation of deformations of creep.