What Are Padstones? Steel Beam Bearings Explained

When a steel beam takes the load of a wall or floor, all of that weight arrives at two small areas — the points where the beam sits on the masonry. A padstone is the block that sits under the beam end to spread that load out, so it doesn't crush the brick or blockwork underneath.

Why they're needed

Brick and block are strong when load is spread across them, and much weaker when it's concentrated. Without a padstone, the end of a beam can put more pressure on a small patch of masonry than it can safely take — which shows up as crushing, cracking, or gradual settlement above the bearing.

The padstone widens the contact area, bringing the pressure down to something the wall can carry.

What they're made of

Usually one of two things:

• Pre-cast concrete padstones — dense concrete blocks made for the purpose, in standard sizes.
• Cast in-situ concrete — formed and poured in place, used where a standard size doesn't fit or the bearing is an awkward shape.

Occasionally an engineer will specify a steel spreader plate, or a full steel post instead, particularly where the wall isn't capable of taking the load at all.

Who decides the size

Your structural engineer. The padstone size comes out of the same calculations that size the beam — it depends on the load coming down, the bearing length, and the strength of the masonry it sits on. It will be stated on the engineer's drawing alongside the beam specification.

This is not a detail to eyeball on site. If the wall can't take the load even with a padstone, the answer is usually posts either side — which is exactly what a goalpost frame is for.

Getting it right on site

A few things that matter in practice:

• The padstone must be properly bedded and fully supported underneath — one sitting on a soft or hollow bed doesn't do its job.
• The beam needs the bearing length the engineer specified. Skimping on how far the beam sits onto the padstone undoes the design.
• Building control will want to see the bearings before they're covered up, so don't plaster over them.

Frequently asked questions

Can I just use a couple of engineering bricks? Only if that's what the engineer specified. Sometimes dense engineering brick is acceptable; often it isn't. It's their call, not a default.

Do both ends need one? Normally yes — both ends are carrying load. The engineer will confirm.

Do you supply padstones? We fabricate the steel — beams, posts, cleats and base plates. Padstones are usually supplied by your builder or merchant to the engineer's spec. Talk to us about the steelwork and we'll tell you what we need from the drawing.