Crack in concrete block wall

Daragh86

I've noticed a crack in the wall of the back of my two storey terraced house, built in or around the 1950's / 60's. The back of the house is pebble dashed. The crack runs diagonally from near roof level down to top of door level. I've read up a bit on this and from not being able to see the actual blockwork I can't determine if this is a stepped crack or not.

I've recently renovated the whole house and where the crack has emerged (and not sure when it did emerge) i've knocked out a 5" dia. hole for the gas boiler flue. Would maybe this have caused the problem?

I can't determine what size the crack is (if it is even in the blockwork?) because the wall finish is pebble dash. Is it possible that the crack is just in the pebble dash?

I am sure I will have to call in a structural engineer but I just want to see if I can get any info on it before or if there is any more investigation I can do (maybe chip away some of the pebble dashing around the area?) ??? As with most these days money isn't exactly plentiful so trying to maybe cut down on some of the costs. Anyone have any advice?

Buford T Justice

Can you post a pic of the crack?

FesterBeatty

Diagonal cracks leading towards the top corner of a window/door ope is a typical sign of settlement - unlikely (but not impossible) that a 5inch core would cause this, however I'd need to see the core location. You could strip off the finish to ensure that it's not just a crack in the render, however its very likely that the block is cracked. I've come across similar issues on numerous occasions and quite often there was a leaking downpipe/broken gulley/burst pipe etc located within a few hundred mm of the foundation. This can result in a change in ground conditions thus leading to foundation movement - however each case needs to be reviewed individually so I can't say for sure at this stage.

I'm a chartered civil/structural engineer and you're welcome to PM me if you like.

Daragh86

FesterBeatty wrote: »

I've come across similar issues on numerous occasions and quite often there was a leaking downpipe/broken gulley/burst pipe etc located within a few hundred mm of the foundation.
QUOTE]

Now that you say it I did repair the concrete around a gully located very close to it...I'm a bit slow to put 2 and 2 together.

So I prob shouldn't have any more problems?

FesterBeatty

Will you have any more problems? Completely impossible to say without seeing it and gaining a good understanding of the problem. It depends on so many factors, perhaps the ground conditions have changed (as a result of years of saturation) and is still moving? Or perhaps it has stabilised, found its new equilibrium and will not move further given that you may or may not have resolved the issue. Perhaps the foundation wasn't built properly in the first place, or perhaps there was an issue with how the wall was constructed etc etc - impossible to say at this stage, but as I pointed out, a likely cause is localised saturation of the ground. If you're worried then you need an engineer to review. If not, and you're happy to live with it as is then leave it and see if it gets worse (in the very short term). If it does get worse - call an engineer.