The hypothesis is that a good cladding system in wood should be characterized by a homogeneous dimensional behaviour with minimal variation between individual panel boards to minimize maintenance, i.e. repainting or, in the worst case, replacement of whole panels. Four different types of cladding panels were tested: a regular spruce panel, a quality-sorted P-marked spruce panel, a regular panel of pine heartwood and a spruce glulam panel, 50 panels of each type. The objective was to study the dimensional changes under changing moisture conditions in order to find the cladding material with the smallest possible dimensional and distortion movements. The shape stability of the panels was measured and expressed in terms of bow, spring, twist and cupping. The spruce glulam panels showed the best shape stability, proven significantly different in comparison to the other two spruce panel systems. Panels of pine heartwood showed a tendency greater dimensional stability than the spruce panels, but not enough to be considered statistically significantly different in this study.