What is a stelnok?
A stelnok (Dutch, roughly “adjusting nib”) is a projecting nib on one building element on which another element temporarily rests, so it can be adjusted precisely from that position before it is fixed. The adjustment can be for height, for position across the line of the element, or for angle. In construction the nib is usually made of reinforced concrete or steel.
The adjustment is made with an adjusting screw in or on the nib. In practice this is almost always a threaded levelling bolt that holds the element at the right level while it is permanently secured. For temporary adjustment a wedge or steel shims under the element may be used instead. English has no single word for this detail; you would describe it as an adjustable bearing nib or a levelling bolt on a corbel.
Where you find it
Stelnokken are typical of precast and prefabricated construction: concrete or steel components that meet on site. Factory-made units are dimensionally accurate, but the structure they sit on always has tolerances. The adjustable nib takes up those differences so the unit ends up level, plumb and in line.
Application
- Adjust first, fix second. Bring the element to level with the bolt, check with a spirit level or laser, and only then fix it or grout the joint.
- Work from fixed reference points. Set out from the datum and grid lines on the drawings, not from the previous element, so small errors do not add up.
- Confirm how the load is carried. Whether the bolt may carry load permanently, or the bearing must be grouted with non-shrink mortar, is set out in the erection method statement or the engineer’s design.
- Secure temporary wedges. A loose wedge can be shaken out by vibration or pushed out by the weight of the next unit.
Common mistake: leaving the levelling bolt as the permanent bearing when the structure was not designed for it. Follow the supplier’s or structural engineer’s instructions for grouting and finishing the bearing.
Related terms
- Tilting nib
- Corbel
- Console bracket
- Precast concrete panel
- Spirit level
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.