Crack in pebble dash brick wall where extension joins house

[ajmetro]

Hi all

First post on here.

I am looking at buying a property however I have noticed a crack that follows the line where the rear extension joins the main house. Wondering if it is anything to worry about. Did not want a survey until I get the professional opinions of others in the know.
The extension is a single story about two metres by four. The area is clay and some gravel and sand.

The house was built in 1936 and the extension around 2011. There are no trees within the area and the house was underpinned in 1991 with certificates that state the work was carried out, however no plans to show where the property was underpinned. The gap of the crack is around 5mm and is filled with mastic. The windows all open as well as the extension door. There is what looks like rising damp within the extension which is within the proximity of the crack.

I have a photo which I have put into my album.

Some opinions would be greatly appreciated as to whether this is subsidence/thermal expansion or settling.

Untitled

• ajmetro
• 29 Dec 2013
• 1

 

[Alastairreid]

Settling! they should have built in an expansion joint.

Unsightly but nothing to worry about.

 

[ajmetro]

I mistakenly said it was 0.5mm when in fact it is around 5mm wide. Does this make a difference?

 

[Alastairreid]

No thats fine, you can run a grinder down it to open it up a bit and fill out with flexible caulk.

 

[tony1851]

+1.
The time to worry would be if the crack was noticeably wider at one end than the other.

 

[ajmetro]

I couldn't notice a significant difference. How much more noticeable are we talking?

 

[ajmetro]

Thanks all who have commented so far. Does the rising damp not provide any clues as to the cause of the crack?

Would the position of the rising damp not suggest that the damp coursing was damaged, it being so near to the crack, would this not suggest movement away from the house including the floor of the extension or could this be something unrelated?

 

[Alastairreid]

What rising damp?

 

[ajmetro]

There is what looks like rising damp within the extension which is within the proximity of the crack.

 

[Alastairreid]

There should be a vertical dpc installed in the cavity between the old and new! so even if there is an open joint the water shouldnt get through to the internal leaf.

If there is a damp problem emanating from the floor it will be either a problem with the dpc, dpm, ground levels choked cavity etc.

Vertical dpc

 

[ajmetro]

thanks for the reply, would this be a easy problem to fix or financially draining?

 

[Alastairreid]

Depends if it is a damp problem and the cause..cant see it being anything major tbh.

 

[ajmetro]

So I have had a surveyor come to look at the property and they say there is structural movement. I then got a structural survey done on the property and they seem to think it is a result of "differential downward movement" and points to the drains as a possible cause.

He had recommended a compression test of all of the access points and has recommended a company to do it.
My question is whether the engineer is covering themselves by saying "differential downward movement" and passing it off to another person (Drain company they recommend) or whether this is another way of saying subsidence?

After all the research online I cant find any subsidence with a vertical crack that goes down the line where the extension meets the old building.
I have already piled over a grand for the surveys should I just walk away from this property?

I spoke to the engineer and when I asked if it was subsidence he went all technical on me and said there are different types of movement. I did feel as though I did not get a straight answer (at least one that I understood).

Any help and suggestions would be much appreciated from those in the know. The picture of the crack is in the first post of this section.

 

[tony1851]

It would be more helpful if you showed a pic of the crack from further back so that we can see the whole picture.
But generally speaking, a crack which is the same width all the way up is more related to shrinkage (laterally) than 'downward differential movement' (whatever that is).
Your problem is that no-one is going to give you a definite diagnosis because no-one will take the risk of being wrong. And all these buck-passing opinions by the professionals are costing you money.

 

[stuart45]

The crack looks more like it's moved sideways, rather than downwards. Differential settlement can occur where an extension settles at a different rate to the house though.