Do I need any props when repairing this load bearing wall?

[lookieluke]

Hi All,

I would like to repair an internal bearing wall around the corner after removing some plumbing mess. The house has cavity walls with the internal wall made of concrete blocks (house in the UK built in 60's). I would like to replace 4 concrete blocks (and 1 brick) as shown on the attached picture. The reason I would like to replace the blocks is that they are cracked vertically where they meet the perpendicular wall. They are cracked not because there is any structural problem, but because the person (not me) installing the pipes through the wall was not particularly professional. My main question is: Do I need any props (e.g. acrows or strongboys) while removing the blocks?

I would appreciate your help/advice.

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• lookieluke
• 30 May 2014
• 1

 

[conny]

It certainly wouldn't do any harm to support the load before starting work on the wall.

Better to be safe than sorry.

 

[lookieluke]

Thanks a lot. I will hire one pair of acrow+strongboy and prop the corner of the wall just above the highest block to be replaced. As you said, better be cautious.

What is worrying me as well is making the horizontal bonds between the new and old blocks strong enough to avoid any cracking in the future. From my search on this forum and the internet in general it seems to me that people either do slate pinning or just try to pack densely the mortar between the bricks/blocks (usually with mortar guns). Is that true?
I found this thread on diynot forum quite informative although it's about a bit different problem:
//www.diynot.com/forums/viewtopic.php?t=102001

I don't have a clear view on all this yet. I would probably go for slate pinning, although don't really know where to place the slate pieces, how big the slate pieces should be and how exactly drive them into the slot.

I was also thinking about attaching (say, with a glue) a plastic mesh or piece of rigid plastic to the back of the old blocks to create a barrier which would not allow the mortar to escape into the cavity. It seems to me that this would allow me to easily and properly fill the gap between the old and new blocks. Do people actually do things like that?

 

[tony1851]

Before you start hacking away at your wall, are you sure thre is a problem with it? And are you sure it was caused by some tradesman?

Concrete blocks are notorious for shrinkage-cracking; it might be that the vertical crack where the walls join is due to normal shrinkage.

 

[lookieluke]

I think I wasn't precise in my initial post. It's not that there is a gap between the 2 blocks/bricks jointed at the corner, but the blocks themselves are cracked. I am 100% sure this was caused mechanically while working on the wall (drilling/banging through the wall while installing the pipes + removing the wooden panels that were supposed to cover the mess).

Here are some close-up pictures that show the cracks:

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• lookieluke
• 1 Jun 2014
• 1

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• lookieluke
• 1 Jun 2014
• 1