In those cases, engineering advice should be obtained. By doing this, several changes occur. This can add to the wind forces that the older building must resist. Previously, some of these wind forces were dissipated as it was, in part, allowed in through the cracks between the siding boards. With solid steel sheathing eliminating this wind movement, an increased pressure occurs.
Wind pressures are very significant on the large wall surfaces of a two-storey barn.
An engineer should determine if additional bracing is required. As well, the natural ventilation provided by a board-sided barn is eliminated by the addition of steel siding. Because of this, moisture is not so easily removed from the loft area. To offset this, louvered or screened vents should be added both to the wall areas and to the barn peak in the upper storey of the barn. They make the task of repetitive nailing easier.