Crack in corner of old extension and crack outside

[DaveHhh1]

Hi,

My property has an old extension circa 1985. It's a detached property 1930s and we have a diagonal crack inside with is a couple of mm thick but deep so it is in the brickwork. Outside there is a diagonal crack also in a different location.

I've had a few builders and people say they aren't concerned and to monitor it but I am concerned. I plan to extend this extension to the side also in a year or two and people are saying "address the issue then if it's an issue." I don't have any cracks like this anywhere else in property.

I think I need to get a structural engineer in. Worrying times. What do we think?

Thanks all

 

[Dereekoo]

Nothing to sort except rake out and make good both faces

 

[opps]

Not my area of expertise, but if it were subsidence, I would expect the cracks to be at the top, rather than the bottom.

 

[Ivor Windybottom]

If that's your biggest worry then you have a good life!

Seriously it's a bit of hairline nothingness. I've seen houses where the entire corner of the building has dropped an inch into the ground.

If it really worries you then screw one of these across it on the outside...

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I put one on a much bigger crack in my place about 5 years ago, it's not moved a bit so I've stopped worrying about it.

 

[DaveHhh1]

Thanks for the replies. I do have a hairline crack inside at the top but not outside. I think what worried me was the cracks are deep inside and out. The blocks are thermalite inside.

I have an engineer coming next week. Will see what they say.

 

[Ivor Windybottom]

If he's from a crack repair company then he'll say it's all terrible subsidence so needs underpinning and helibars, all within a month before it falls down, and here's a 20% off deal that's only available if you sign here now. I've just phoned the boss, he's really cross about me giving that 20% discount but will allow it as I've already offered it.

 

[DaveHhh1]

Yeah I must admit to having reservations. Hopefully because he's not from a crack repair company he won't say that but you never know. I think he will just say "needs more inspection of the foundation." Which is no better off than I am now.

 

[Notch7]

Worrying times. What do we think

Nothing to worry about.

Internal: you’ve got a reasonable panel of blockwork across under the window which joins a narrow full height bit of blockwork…..not surprisingly that’s a stress point from the corner of the window.

Externally it’s cracked on the render, impossible to know without investigating whether it’s just the render or the blockwork / brickwork. If it was the blockwork It’s more common to see cracks tracking along the mortar lines than just diagonally, depending what blocks they are.

 

[DaveHhh1]

Nothing to worry about.

Internal: you’ve got a reasonable panel of blockwork across under the window which joins a narrow full height bit of blockwork…..not surprisingly that’s a stress point from the corner of the window.

Externally it’s cracked on the render, impossible to know without investigating whether it’s just the render or the blockwork / brickwork. If it was the blockwork It’s more common to see cracks tracking along the mortar lines than just diagonally, depending what blocks they are.

Hi, I think outside it is the brickwork too I was able to insert quite deeply a scraper used for filling gaps at the bottom same as I side. The bricks are thermalite bricks. This is what's got me concerned.

 

[Notch7]

The blocks are thermalite inside

They are really weak, even new work gets cracks in it.

When building with thermailtes you have to make the mortar weak or it ends up being stronger than the block and leads to cracks.

 

[DaveHhh1]

They are really weak, even new work gets cracks in it.

When building with thermailtes you have to make the mortar weak or it ends up being stronger than the block and leads to cracks.

Thanks, so what's the remedial action am I screwed? Extensions been standing since 1985, I'm panicking.

 

[opps]

Thanks, so what's the remedial action am I screwed? Extensions been standing since 1985, I'm panicking.

Again, not my area of expertise, but I don't think, based upon the replies from people more knowledgeable than me, that you need to panic.

If your extension were to pull away from the rest of the building and drop down, as I suggested earlier, you would expect to see the larger cracks at the top of the extension, and not at the lower parts.

Think of a wall leaning away- the evidence is more obvious towards the upper part of the wall.

 

[ree]

OP,
Presumably the "engineer" is a SE? By mailing the pics & information you've posted here to the SE they might advise you without the expense of a site visit?
Did you view the original thermal masonry build?

FWIW:
There appears to be a sand & cement fillet at the base of the outside skin - why?
Render should stop just above the DPC bed - it should finish with a Bell Cast.
The external crack, as it is, could allow moisture penetration to rust the corner metal angle bead.
Rusting beads swell & blow the render.

 

[DaveHhh1]

Hi, I was not aware there is sand and cement at the base. Thanks for advice on the exposed crack allowing moisture in. Is the fix to rake out and make good?

I did send the engineer pics. He wants to evaluate the site for trees etc before making an opinion. Of course he does. Dreading the underpinning solution.

 

[ree]

OP,
No, for the time being simply seal the outside crack with an easily removable sealant. Or leave it alone until the SE makes their visit?
FWIW: you could pre-dig a test pit at the corner if subsidence is on your mind?