Building piers for RSJ

29 Feb 2012
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United Kingdom
Hi guys,

I'm installing and pair (cavity wall) of RSJs spanning a 2900mm opening to open my kitchen out into a kitchen-diner. I've had the necessary calcs done for the beam and submitted application to BC... My SE has spec'd that I need to build up piers either end of the RSJ 150mm x 300mm (300mm across the cavity wall and 150mm for UB to sit on). What's the easiest brick / block size to create these piers - I'm trying to avoid cutting every brick to size. I've looked at using engineering bricks 102.5x65x215mm on their sides arranged 2 parallel to the wall and 1 cut to size across the ends (perpendicular to the other 2) - hope that makes sense... Alternatively my SE suggested "3xno. 100x225 blocks cut down to pier size" - I presume this means 100x215x440mm dense concrete blocks cut down from 440mm to say ~140mm - would this approach be better / is it OK since there is no differing bond pattern between the courses? Or have I misunderstood my SE?

Also, to bond the piers to the existing walls would brick ties be OK? The house is a 1930s build and the block construction of the cavity walls would make it difficult to cut out any blocks to fit overlapping blocks into the piers.

Any help on the above would be greatly appreciated.

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Load bearing piers really need to be properly bonded, not tied

You would normally build the pier to the nearest larger brick or block dimension
Thanks for the response Woody. I was going to use a wall starter, but I guess this isn't sufficient... :(

I think the blocks are a funny dimension, so not sure i'll get something to match. If I use concrete blocks 3 x perpendicular to wall followed by 2 x parallel for the next course, would it be sufficient just to tie in the central block of the three block layer into the existing wall, i.e. 1 block every other course?
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Why has your SE asked for piers at both ends? I can understand having one to avoid damage where the beam might otherwise project into an adjoining room, but presumably, the other end will sit in the side(gable) wall.
A beam of 2.9m span will not be very heavilly loaded and we have done many of these without using piers on the side wall, which can be a pain when fitting units etc.
If the padstone is a suitable length, say 400 long, cut from a 6" x 4" p/c concrete lintel, this would normally be OK to spread the load sufficiently over the existing blockwork to avoid having a pier. We have done this when the inner skin is just aerated concrete block (eg Celcon); a 400 long padstone on 100 celcon block will take a factored load of around 40Kn, which is probably more than the reaction from your beams.
Other factors may, of course, apply (such as an excessively slender wall, or ropey blockwork) but I would still have a word with your SE and ask exactly why a pier should be required.

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