Question $1.$ A $102\mathrm{.}5mm$ thick single skin brick wall, as shown in Figure $1,$ is built between the concrete floors of a multi$-$storey building. It supports an ultimate axial load including an allowance for the self$-$weight, of $250kN$ per meter run. What brick and mortar strengths are required if normal manufacturing and construction controls apply and the wall is first $10m$ long and secondly only $1m$ long?