The housing must be executed in compliance with the ISO H8 tolerances; the outer diameter of the shaft seals has a tolerance that ensures a stable fit between the shaft seal and its relative seat.

The surface finish of the housing must be in the range of 1.6 µm to 3.2 µm Ra, or < 16 µm Rmax. Roughness levels below or above these limits may cause the gaskets to slip out of their housings (due to vibrations) or may damage the rubber faces, respectively. In any case, it is always desirable to provide a shoulder stop for the shaft seal.

The shaft seal's access to the housing must be favored by an appropriate chamfer applied to the access side of the seat, of not over 20°, having a minimum depth of 1.3 mm for rings of a height up to 10 mm, and of at least 1.8 mm for rings exceeding a height of 10 mm. Burrs or sharp edges must be absent. For bearing seats made of soft materials (for ex.: light alloys) and for thin-walled seats it may be necessary to adopt a different interference between shaft seal and housing. The tolerances will therefore have to be determined by practical installation tests. If one component (for ex.: the bearing) must be installed by passing through the seat of a shaft seal, the latter may be damaged. In this case it is appropriate to choose a shaft seal (and its relative seal) with an outer diameter exceeding that of the bearing.