I Can’t Find the Padstone You Specified — What Should I Do?

Non-standard padstone sizes are sometimes hard to source from builders’ merchants. If you can’t find the exact padstone on the drawings, there are two accepted alternatives — and one approach you must avoid.

Option 1: Cast In-Situ

Construct formwork and pour a C35 concrete padstone in position. This is the most flexible option and works well for unusual sizes or where access to the bearing location makes pre-casting impractical.

Option 2: Stack Concrete Lintels Vertically (On Edge)

Standard concrete lintels, stood on their narrow edge, make a perfectly suitable padstone material.

Critical rule: stack them vertically (on edge) — not side by side.

Stacking lintels side-by-side creates a joint running directly under the beam flange. Under load, this joint is prone to splitting. Stacking them on edge (like books standing up) puts the joint between them at the side, away from the bearing surface.

What You Must Not Do

– Do not substitute a smaller padstone without engineering approval — the size has been calculated from the load
– Do not stack lintels flat (side by side) — the joint under the beam is a structural weak point

If the Wall is Narrower Than the Padstone Specified

Contact PorthouseDean before proceeding. If the padstone width exceeds the wall thickness, it will bridge the cavity or project beyond the wall face — neither is acceptable. The engineer may need to revise the padstone size, which requires a load check at a reduced bearing area.

Get in touch with us if you are unsure which alternative is appropriate or if the specified padstone does not fit within your wall construction.