Advice needed - diagonal crack in internal wall, matching on both sides of the wall

[H Poules]

Hello. I have a back-to-back red brick mid terrace house in the UK. There is a large crack in an internal wall on the 2nd floor. The wall between the bathroom and the bedroom. The crack runs diagonally up in a step pattern from the bottom corner where the wall joins the external wall. The crack is visible on both sides of the wall. It is no more than 5mm wide at its widest parts. I cants see signs of cracks on the walls below. Can this be due to the support of the 2nd floor weakening? Or is the wall bowing. Please can anyone help me work out what is happening and what might need doing to fix it please

[Tim+]

A picture is worth a thousand words...

Tim

[Brian Gaff (Sofa)]

You need a surveyor. Is the house on a hill, what sort of foundations has it got and are any other similar houses locally having similar problems.. Some older builds seem to be made to creep and the cracks widen and narrow as the soil expands and contracts. Brian

[harry]

The important thing is that it doesn't get any bigger. if it's still moving you have trouble. It needs to be monitored fora few weeks. A lot of old houses built on clay didn't have the foundations deep enough. In dry weather clay near the surface shrinks.

If not getting worse, it can be fixed with a crack repair kit.

If it is getting worse, remedial work could be a major expense

[Martin Brown]

Two obvious questions are:

Is it in an old coal mining area? Or on a heavy clay soil?

Is there a wall on the ground floor underneath where the upstairs wall that has cracked is or was there one in the past?

I recall someone in my youth who decided to DIY knock out the central ground floor wall between front room and dining room when open plan was very fashionable (but without putting in an RSJ in to take the load). It did not go well but was entertaining for onlookers!

An RSJ that isn't quite up to the job might explain it.

You definitely need a surveyor to look at it in person and probably to put some tell tales on it to see if it is still moving and how fast.

Advice on Usenet may be worth less than you have paid for it.

[Kellerman]

You need professional advice from a Building Surveyor. Contact your Buildings Insurance Company.

[Andrew]

An RSJ that IS up to the job sometimes doesn't help if the point loading onto the foundations makes the latter fail, whereas previously the weight was evenly supported along the whole foundation.

Any BCO doing the job properly would insist on an excavation to check the foundations and widen/deepen them if necessary.

Andrew

[Andrew]

'Terraced back-to-back'

This this mean potentially 5 party wall agreements to fix this ?. (2 on one side, three on the back).

[Martin Brown]

I think only the two immediately adjacent party walls are relevant.

The way I remember terraced back to back there was always a high walled paved back yard containing the outside loo, coal bunker and sometimes a token garden about one flagstone in size. Rows separated by a narrow alleyways where the bins lived at the backs and a road at the front.

[Roger Hayter]

Proper back to back terraces, at least in Leeds, had rear party walls and, presumably, a toilet block for each terrace. The back yard and ginnel was a posh arrangement for ordinary terraced housing.

[newshound]

Basically I'd just support everything Martin and Andrew have already said. This is, presumably, Victorian and as mentioned elsewhere they did not have foundations to modern standards. Coal mining can take down even modern houses.

A key point is whether it is still moving. I used to live in a Georgian update of earlier "cottages" that experienced "front to back" subsidence, so that (for example) doorways in stud walls that went "sideways" across the house had shifted over time into parallelograms with 30 mm of "drop" across their width. But that was a *long* time ago and it wasn't moving when I lived there. A neighbour has just done a major refurbishment of an 18th century cottage with rubble-filled stone walls. He was paranoid about a similar crack in an external side wall even though I was able to tell him it had not moved significantly in decades. He put in a "microscope slide" type tell-tale that did nothing over several months, but he still did a substantial rebuild including adding an anti-bow tensioner (although there was no obvious sign of bowing).

If you don't want to rush into paying a surveyor there must be internet advice on DIY "tell-tales". Houses very seldom fall down, and usually give quite a lot of warning (unless on cliff edges or over old, near-surface mines).

[Andrew]

Those are ones that I meant. They only have windows at the front because the rear wall is also the rear wall of the row of terraced houses on the other side, all sharing the same run of roofs.

[Max Demian]

I don't think the OP meant a real back-to-back of that kind, most of which have been demolished. I suspect he means 1st not 2nd floor too.

[Andrew]

I've seen at least two appearing on Homes under the hammer, both in Leeds (convenient for students).

[Tricky Dicky]

The OP did not mention problems with the wall below which would suggest that maybe the external wall is bulging out on the upper storey. The OP needs to get the problem assessed ASAP by a surveyor.

Richard

[Vir Campestris]

+1

(I wouldn't normally add +1, but this is exactly the right thing to do in a situation where doing the wrong thing could be _very_ expensive)

Andy

[Martin Brown]

More than that if it has just recently appeared then any delay could allow it to become considerably worse and even dangerous.

Where I used to live entire semis and the odd detached house or parked car would occasionally disappear into the ground due to mining subsidence or sink holes. Old buildings were built on timber frames and more modern build on concrete rafts so that they might tilt a bit under provocation from mining subsidence but the walls didn't usually crack.