A padstone is a solid block - usually concrete or engineering brick - built into a wall under the end of a beam. Its job is simple and vital: spread the beam's concentrated load over enough masonry that the wall underneath doesn't crush. It's the least glamorous item in a beam design and one of the most common things Building Control checks.
Why beams need them
A steel beam carrying a floor and a wall might deliver several tonnes into each bearing - through a contact patch only as big as the beam's flange. Ordinary bricks and blocks, especially lightweight blocks, can't take that pressure directly: they crush, the beam drops a few millimetres, and cracks appear above the opening. The padstone converts the point load into a spread load the wall can carry - the engineer sizes it so the bearing stress lands within what the masonry below can safely take.
What they're made of, and typical sizes
- Precast concrete padstones - the standard choice, in off-the-shelf sizes (e.g. 215×100×102mm up to 440×215×215mm)
- In-situ concrete - cast to suit where an odd size or length is needed
- Engineering brick (class A/B) - traditional and still acceptable for lighter loads
- The size isn't guesswork: it comes out of the beam calculations, matched to the bearing load and the wall's strength
When you need one - and when you don't
Most domestic steel beams need padstones at both bearings; lightly loaded lintels on strong masonry sometimes don't. The answer is in the calculations, not a rule of thumb - which is why our beam packages always include the bearing design and padstone specification, and why 'beam bearing directly on blockwork' is a defect we regularly record in structural surveys of altered houses. If you've had work done and there's cracking above an opening, that's a familiar story with a designed fix.
Frequently asked questions
Does Building Control require padstones?
Building Control requires the beam bearings to be justified in the calculations - where the masonry can't take the bearing stress directly, that means padstones, and the inspector will expect to see them on site as specified.
Can a builder just use a couple of engineering bricks?
Sometimes that's exactly what the design specifies for lighter loads - but it needs to be designed, not assumed. Heavier beams on blockwork almost always need a concrete padstone.