Abstract: A cushion block for using in a build-up surface formed by strips is disclosed to have two male coupling devices at one end, two female coupling devices at an opposite end corresponding to the male coupling devices, a retaining device protruded from one side thereof and adapted to secure the strip to the corresponding side of the cushion block, and a deformable body connected between the male coupling devices and the female coupling device. The male and female coupling devices are so made such that multiple cushion blocks are connectable in a line in a linking direction by engaging the male coupling devices of one cushion block into the female coupling devices of another. The deformable body is deformable in the linking direction to compensate expansion of the strips due to absorption of moisture.