A $2440$ ft $(7\mathrm{.}312\mathrm{.}2$ m$)$ building has a full basement with uninsulated walls extending $5$ ft $(1\mathrm{.}5$ m$)$ below grade. The insides of the walls are finished with R$-8($R$-0\mathrm{.}7)$ insulation,a thin vapor barrier,and in$.(12\mathrm{.}7$ mm$)$ gypsum board. Estimate an overall heat$-$transfer coefficient for the walls.