Tapering is the gradual narrowing or thinning of a structural element towards the top or towards one end. In construction, tapering is mainly applied to columns, pillars, chimneys and walls that become narrower towards the top. This saves material and gives a more elegant appearance, while the structure is most heavily loaded at the bottom, where it is also the thickest.
Characteristics of tapering
| Feature | Description |
|---|---|
| Principle | Gradual reduction of the cross-section |
| Direction | Usually from bottom to top |
| Profile | Straight (conical) or curved (entasis) |
| Purpose | Material saving, aesthetics, optical correction |
Applications
- Columns: classical columns are thicker at the bottom than at the top
- Chimneys: become narrower towards the top
- Towers and steeples: taper in stages or gradually
- Concrete columns: sometimes executed conically to save material
- Piles: driven piles often taper to a point
Entasis
A special form of tapering is entasis: a slight convex curvature in a column. This is an optical correction that prevents a straight-tapered column from looking concave. The column is slightly thicker at about one-third of its height than at the bottom or top.
Expressing the taper
- The degree of taper is expressed as the difference in diameter or width between bottom and top
- For example: a column of 400 mm at the bottom and 300 mm at the top has a taper of 100 mm
- The ratio of taper to height determines how slender the column appears
Tips for the DIY enthusiast
- When building a chimney in brick: step in by half a brick every few courses
- A taper must be symmetrical to ensure even load distribution
- For timber columns: taper with a plane or router, checking regularly with a template
- Keep the taper subtle: too much narrowing gives an unstable appearance
Related terms
- Entasis
- Taper
- Column
- Pillar
- Classical orders