Relief currently exhibited in a later-made frame of natural wood that hides its back. The original support can only be seen in those places where polychrome decoration is missing and partially along the sides where the marks of adzes used to tailor and fit the group of figures into the original frame may also be observed. The original frame is unfortunately missing today. Saw marks may also be seen to the back of the altarpiece. The hands of Saint Joseph and the midwife - all of which are missing today - were pieces made separately and then attached to the main figures using mortise and tenon joints.
Particularly noteworthy is the detailed gouge work used to represent superficial irregularities such as grassy and rocky areas. The use of fabric under the polychrome decoration may be observed, though this could have been added after the original decoration was applied.