The use of SMC as an additive for making FCBs has been shownas another feasible way to recycle this residue generated by mush-room factories. Results were similar to those founds in literatureand new parameters; as TC and plasticity, were described.It is possible to decrease the TC of FCBs up to 26.17% adding17% of SMC which means a TC value of 0.55 W/m K. The equivalentthermal transmittance of a wall can be decreased by up to 10% byreducing the conductivity of the clay by up to 26% without changingthe type of block or the type of wall assembly.Fired clay made by adding up to 17% SMC enhance thermal prop-erties of bricks while WA and CS values are according to standards,however bricks could be non-accepted by market with so low com-pressive rupture strength and this may limit the addition of amountof SMC.The preparation procedure of the samples assures the repeat-ability of results in real scale, but organic gases could limit theamount of additive used, as well it could make mandatory anexhaust gases treatment installing. For these reason it is recom-mended to analyze this issue in deep before produce it at realscale.