The results revealed that the new blocks manufactured with wheat straw fibre have a relatively high density varying between 1575.6 and 1357.7 kg/m3 for 1% and 3% fibre contents. This corresponds to a decrease of about 9.8% to 22% at 1% to 3% fibre content in comparison to clay bricks without fibres. For barley straw reinforced bricks, it can be seen that the density ranged between 1542.5 and 1139.9 kg/m3 . This means that the density decreased from 11.6% to 34% when the fibres content increased from 1% to 3%. The results illustrate that increasing of wheat straw fibre percentages from 0% to 3% caused thermal conductivity percentages to decrease from 0% to 54.4% in comparison to bricks without reinforcement fibres. Also, increasing barley straw fibre percentages from 0% to 3% caused thermal conductivity percentages to decrease from 0% to 53% of the reference specimen, results which are extremely satisfying. Finally, the increasing of gypsum percentages from 0% to 10% caused thermal conductivity to increase from 0% to 48.7% in comparison to brick materials without gypsum and with 3% wheat reinforcement fibres. For barley straw fibres, increasing gypsum percentages from 0% to 10% caused thermal conductivity percentages to increase from 0% to 51.6% with the same fibre content.