A padstone’s length, width, depth and material cannot be determined from the beam designation alone. Previous generic size examples on this page have been withdrawn. The examples below compare arithmetic contact pressures only.
Same force, different assumed area
Suppose an illustrative reaction is 20 kN:
| Assumed rectangular contact | Area | Average force / area |
|---|---|---|
| 300 × 200 mm | 60,000 mm² | 0.333 N/mm² |
| 200 × 200 mm | 40,000 mm² | 0.500 N/mm² |
Reducing the assumed area raises the average pressure. Neither row is a padstone recommendation or proof that masonry can sustain the load. The calculation does not establish effective contact area, load spreading, eccentricity, material resistance or padstone depth.
Information missing from a pressure-only example
A real support detail needs the beam reaction and loading combinations, beam position, available wall width, masonry condition and the engineer’s assessment of the load path. An apparently large padstone on unsuitable masonry does not fix the support automatically.
When reviewing the engineer’s drawing, check that the beam designation, reaction, bearing detail and support location belong to the same revision. Ask the designer to resolve a site mismatch before work proceeds; do not choose the next larger stock block using this table.
Use the bearing pressure illustration to reproduce the division, and Approved Document A for England’s structural guidance. A chartered structural engineer must specify the actual design, with the applicable Building Control approval.