Possible subsidence to extension. How concerned should I be? Please help!

[adamadam]

Hello,

I am in the midst of purchasing my first home. The property is a 3 bed semi detached.

The property garage at the back was converted into a room and an extension/garage was built to the front (single storey)

Directly under the left side of the window (on the outside) at the back, you can see some zig zag cracks (see photo below)

We had a survey report and it says further investigation is required (see photo of comments below). Also, the roof is in terrible condition with sitting water, and inside the room, there is cracking along where the ceiling meets the wall, not sure if this is related to the possible subsidence or separate issue (see photo of surveyor's comments for that too below).

Is the crack in the extension and the thin crack in the ceiling enough to suggest that subsidence has occurred? Or could it just as likely be something more harmless?

We’re looking at getting a structural engineer out, but we’re not sure about paying out for this if subsidence seems quite obvious…..

I'm aware that subsidence and underpinning can lead to various difficulties, particularly with insurance and reselling the property. Would underpinning in the extension alone lead to such problems, or would issues only arise if the main building needed underpinning?

What could it mean for us if we purchased a house with a crack in it, even if it hadn’t been officially recorded as subsidence? The mortgage has already been approved for the property.

Any advice really would be greatly appreciated.

Many thanks

Adam

 

[^woody^]

The crack by the door is more likely the door being slammed, and this rocks the top corner of the wall it is fixed to. Common and not foundation related.

The crack between wall and roof is not indicative of any subsidence - ie why would the wall go down and the roof stay up! . More likely related to the construction (ie type or quality and not necessarily a defect) plus the previous occupant's use of (or lack of) heating the property.

As for the roof, any structural sag would crack the ceiling, not just pond water. Yes the ponding on the roof could do with addressing once the covering is replaced (its not clear if it needs replacing yet), but that's an extravagant comment that the actual roof needs replacing plus the top of the wall! And bizarre to suggest a roof is fitted to an engineers design. I think you got the apprentice surveyor.

 

[oldbutnotdead]

Is there any documentation for the extension (planning permission, building control signoff, that sort of thing).
Hard to tell from the pics but the walls look very thin (looking at window reveals)- low odds it's a cavity wall never mind being insulated to any acceptable standard. Have a measure (or see if surveyor mentions half brick walls anywhere).
Looks like a cheap build but those cracks aren't anything to write home about.
Back in normal times the (assumed) lack of building control signoff would be grounds for a decent reduction in price- but these aren't normal times...

 

[adamadam]

Is there any documentation for the extension (planning permission, building control signoff, that sort of thing).
Hard to tell from the pics but the walls look very thin (looking at window reveals)- low odds it's a cavity wall never mind being insulated to any acceptable standard. Have a measure (or see if surveyor mentions half brick walls anywhere).
Looks like a cheap build but those cracks aren't anything to write home about.
Back in normal times the (assumed) lack of building control signoff would be grounds for a decent reduction in price- but these aren't normal times...

No documentation, it was built 20 years ago. Just found out it was a garage conversion (maybe explains the thin walls?), and then a new garage was built at the front, and between the two is a kind of a foyer area. Flat roof across all of it.

 

[oldbutnotdead]

Yeah that explains the thin walls and those cracks- as @^woody^ , door slams will do that, especially on a halfbrick wall.
Cheap conversion, it'll cost a fortune to heat, wouldn't be a big surprise to find way undersized joists in the roof as well as no insulation (the internal upstand on that nasty roof light looks like 300mm, alas the external looks like 100 or 150 so not much space there for timber).
So not a showstopper, if you can negotiate a reduction do so & if you can budget for a reroof with insulation then do that as well (though you may hit problems with permitted development height limits).