Crack in Orangery

youth_leader

And is one air brick enough?

Section62

hdh74 said:

We're making a list of questions for the surveyor as we go through the report.

Ask the surveyor to explain how they think the roof is held up.

Also whether they think the heavy tiles were part of the original construction, or a later addition/conversion.

I'd suggest that crack could be quite significant... but I'm not a surveyor.

Do you have the budget to do a demolish and rebuild if it comes to that?

stuart45

Section62 

I'd suggest that crack could be quite significant... but I'm not a surveyor.

I think it could be significant as well. The crack does go through the DPC, and I'd like to know the story of how the blockwork came to look like that under the frame. They've split some blocks to get the top level, and none of it runs courses with the ends.
It could well have a shallow foundation.

Bendy_House

Hdh, see how much research you can do yourselves to prepare.

Eg, go on to that LA's Planning Portal, type in the postcode and see if anything comes up about that 'rangery.

And try a 'historic' Google Maps/Earth to try and see when it was built.

hdh74

Bendy_House said:

Hdh, see how much research you can do yourselves to prepare.

Eg, go on to that LA's Planning Portal, type in the postcode and see if anything comes up about that 'rangery.

And try a 'historic' Google Maps/Earth to try and see when it was built.

That's very helpful thank you. Can't find anything regarding planning permission - though the solicitor's searches might find something I haven't - but I can see it was built by 1999 - can't get an image before that. I'm thinking anything serious with the original build would have shown up before now but wondering if the window was replaced and caused the crack. 

stuart45

It looks to me like the masonry under the window was rebuilt just before the window was installed. If you look at the left end the blocks don't line up with the other ones at the squint corner. The DPC is level, then they have used a really thick bed joint for the course above. 
The crack has occurred at the weak spot where the new work meets the existing. It possible there is some extra loading on the pier on the right which has caused the movement. 

Section62

hdh74 said:

 I'm thinking anything serious with the original build would have shown up before now but wondering if the window was replaced and caused the crack. 

This crack potentially is the something serious, but like stuart45 I wouldn't be surprised if the structure has been significantly altered at some point since it was first built.

Do you have a picture of the outer corner - which is just outside to the left on the picture you've posted already? From what can be seen there doesn't appear to be anything that looks of sufficient size to support the roof, unless there's an external corner post we can't see?

I think there's a good chance the windows facing the camera have been installed in place of a doorway or different windows, and perhaps there was something more robust in terms of the original framing. It is possible the foundations are light because there was only a door/window above them.  If someone comes along and changes out the original window/door for a set of windows which change the load path, it is quite likely the altered loading could cause the foundations to fail and lead to the cracking seen.

A crack which runs through a DPC is a red flag, and I don't see how the surveyor could have seen that crack and yet reported there was no significant cracking found.  You need the surveyor to explain this.

hdh74

There's no external post. 
These are the pics from the other side. I'm not sure if I can see a crack under the curved window or if I'm imagining it. Also is the last pic the damp-proof course and should it look like this please?

Section62

hdh74 said:

There's no external post. 

OK, so unless the roof structure is cantilevered out of the main house (pretty unlikely) a significant proportion of the roof load has to be taken by the window framing.  I don't see enough 'structure' in the jambs and mullions for that load to be adequately supported... hence the first question I suggested putting to the surveyor, how is the roof held up?

This is a much larger structure than a typical bay window, and with the prevalence of bay wall cracking where uPVC windows have been inexpertly installed, I'd expect this to be something a surveyor would pay particular attention to.  Seeing a crack in the wall with a structure of this kind ought to ring some alarm bells.

GDB2222

I must say that I was surprised with the initial comments on this thread, ie that this was just the mortar between the blocks and nothing to worry about. I was worried, and I’m not even going to buy the house!

It is a vertical crack through the foundations, after all. 

We are In London, on shrinkable clay, and there’s a lot of subsidence around the area.