Victorian bay window subsidence crack (1.3-3.7 mm); should I pull out?

mattheus

• Surveyor thinks there is 50% probability might need underpinning in the future. But need to observe, ladidada. There is another smaller crack lower centre of bay window, but that one is only about 0.4 mm wide.
• House fairly bastardised and on ugly street, but big, well connected, regeneration in area.
• Have an alternative of a smaller, worse connected house without any cracking on bay window and less bastardisation.

Doozergirl

It's only a bay window.  Fairly common for them to subside as they have different foundations to the main house so it's differential movement. 

I'd be tempted just hire someone to do the work if the house price is reasonable enough.  I'd definitely rather live in a preferred area than freak out over a bay window.  

Investigate cause (any leaking guttering etc)  and remove the paving from around the bay window and ensure the ground level is lower than inside - let it breathe in future.  Check the floor inside the bay - bouncy? 

mattheus

Floor very bouncy. What I am worried is resellability if it gains tag "underpinned". Priced at 450k; in-line with other houses in area; probably up 100k to what it was 4 years ago.

That's the thing. Surveyor could not identify cause: no leaking gutters, no trees. So he only shrug and said -- movement. Which is a harder position to rationalise.

FreeBear

Not seeing any air bricks either. There would typically be one every 8' (2.4m) or so along each outside wall. Might find some wally has buried them under the paving...

At £450K, is this in London ?

Victorian properties often had minimal foundations, and London is predominantly clay which is subject to swelling & contracting depending on the amount or rain.

mattheus

• Maybe it's the house sinking rather than the added paving that hid the air-bricks?
• Yes, London.
• Maybe can negotiate a 30% price reduction due to that wide crack and property depreciation risks involved?

stuart45

Unlikely for the house to drop that much. When first built they will settle for the early years on clay, but then stabalise.
30% would be a lot to get off for that problem but if you can get it best of luck.

Doozergirl

mattheus said:

• Maybe it's the house sinking rather than the added paving that hid the air-bricks?
• Yes, London.
• Maybe can negotiate a 30% price reduction due to that wide crack and property depreciation risks involved?

It's differential movement.  The ground swells and contracts. You're in London, on clay so it definitely does that more than in many other places.  The bay will
have very little in the way of foundations compared to the house, so you get cracking as it can be affected more easily.  

You're not going to get 30% off a house for a crack in a miniature wall on a window.  

I get that people get twitchy about things but it's not really founded in logic, especially when it's just a bay window AND when every period house in London is at exactly the same risk.  If you removed the bay altogether and put in a big window, the issue doesn't even exist, but it would look ridiculous in the street scene.  A couple of cubic metres of concrete and the job is done and the risk pretty much eliminated.  Not even worth an insurance claim.  

FreeBear

Doozergirl said: It's differential movement.  The ground swells and contracts. You're in London, on clay so it definitely does that more than in many other places.  The bay will have very little in the way of foundations compared to the house, so you get cracking as it can be affected more easily. 

The render is probably making the crack worse than it actually is. 3-5mm cracking is minor, and as long as it is just in the mortar joints rather than going through bricks, isn't really much to loose sleep over.

20mm+ cracks than you can see daylight through is an entirely different matter !

Doozergirl

FreeBear said:

Doozergirl said: It's differential movement.  The ground swells and contracts. You're in London, on clay so it definitely does that more than in many other places.  The bay will have very little in the way of foundations compared to the house, so you get cracking as it can be affected more easily. 

The render is probably making the crack worse than it actually is. 3-5mm cracking is minor, and as long as it is just in the mortar joints rather than going through bricks, isn't really much to loose sleep over.

20mm+ cracks than you can see daylight through is an entirely different matter !

Yes, you're right.  I was trying to work out if it was very cementous (and therefore brittle)  as well, or just old, dirty white paint underneath.    The more I look, the more grey I see, it almost looks like pure concrete.    

There's rules about what you put on a SPIF, but the issue could be fixed with no visible problem left and no one would be any wiser.  To me it's a fairly minor issue.  The house is not subsiding, I would not call it subsidence.  

Section62

mattheus said:

• Surveyor thinks there is 50% probability might need underpinning in the future. But need to observe, ladidada. There is another smaller crack lower centre of bay window, but that one is only about 0.4 mm wide.
• House fairly bastardised and on ugly street, but big, well connected, regeneration in area.
• Have an alternative of a smaller, worse connected house without any cracking on bay window and less bastardisation.

Is the bay single or double storey?  Flat roof, or tiled/slated?

A photo from slightly further back to give context would help.

mattheus

Details of the crack: