Use the most conservative value from table $5-5($highest U$-$factor or lowest R$-$value

in the range$)$

Use non$-$reflective, surface emittance $=0\mathrm{.}90$ for interior air film

Calculate the winter U$-$factor for a wall consisting of $6-$in$.$ face brick, $4-$in$.$ common

brick, and $1/2$ in$.$ of plaster $($lightweight aggregate$).$

assume:

Face Brick $-$ fired clay @ $140l\frac{b}{c}u.ft.$

Common Brick $-$ fired clay @ $120l\frac{b}{c}u.ft.$

Plaster $-$ lightweight aggregate @ $45l\frac{b}{c}u.ft.$