Padstone Sizing Confusion

11 Jan 2007
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United Kingdom
I’m opening up the side of a room – creating a span of 2450mm. At one end the beam is supported on a brick pier (remainder of existing wall) creating a 300mm bearing, at the other by going into the wall perpendicular to it – 150mm bearing. Walls are 225mm solid brick (commons). Beam is two 178x102 UBs side by side.

My drawing from the structural engineer shows one p.c.c. padstone spreader 675w x 150l x 150dp to go into the wall perpendicular to the beam – but the wall is 225 thick. Should it be situated in the middle of the wall, the side away from the span or nearest it? Or should it just be as big as the wall thickness?

The pier has a p.c.c. padstone 225w x 300l x 150dp – presume this is right and it doesn’t need to be any longer the bearing of the beam? Also – a few quick web searches showed some BCO guidelines suggesting a minimum of 225 depth for padstones supporting beams of this gauge spanning over 1.8m.

Would it really matter if I made the padstones 225dp anyway – just in case?

Many thanks,
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If you paid this guy, then make him earn his money and ask him to clarify his work!

I presume the engineer has calculated these, so just go with these sizes - you can normally oversize but not undersize.

The padstone normally sits on the inside face of the wall.

The web BCO guides are just that - they were not written specifically for your beam - that's what your engineer has done
You could increase the height of the padstone which would be better because the load from the end of the beam has to spread through the padstone into the full plan area of the padstone base, which it may do if there is reinforcement within the padstone (i.e. - cut down lintel). If the padstone is concrete alone the load won't spread and is therefore not doing much. You could make it the full thickness of the wall but it depends how you are planning to go about installing it because you may need to leave half of the thickness in to provide temporary support to the structure above.

Like Woody says, give the engineer a call. You might be able to get away with a padstone 100mm thick to fit nicely in half the wall thickness.
For a small beam and load like this an SE will usually just pick a standard size padstone. If a different size would be easier to build in I would go back to the SE and ask if the alternative would be acceptable. 95 times out of a hundred it will be.

PS we have just built 406x176x60kg beams, which take a very large floor area, onto to padstones quite a bit smaller than the ones you mention above.
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Thanks for the replies - we've ended up going for the larger 225mm depth. In any case, given the condition of the 130yr old brickwork it would have been almost impossible to pour them out smaller - indeed had to rebuild most of the pier with engineering brick and pour out the full wall width for part of the spreader, old brick was so crumbly. Steel's been in for a week and solid as rock.

PS - My SE is okay - but slow, needed to get on! :D

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