Significant crack in rubble stone wall - how to address?

[lookseehear]

We've recently moved out of our renovation/retrofit and that's meant more of the old fabric could be removed. We took the old kitchen out which had been there 30+ years and there's a significant crack in the stone wall behind where some cabinets and tiles were located. the most concerning aspect of this is that there's a similar but less significant crack in the wall opposite which would indicate that it's the front wall of the house that's leaning outwards, and before I plastered I noticed another even smaller crack on another similar wall. Hopefully the pictures below help to illustrate the problem. I've numbered the cracks 1 - the big one, 2 - the one opposite in the same room, 3 - the smallest one. Old walls are dark gray, newer walls are light gray which are a mix of 1970s concrete block cavity walls and new cavity walls.

 

 

 

 

I've also put an arrow to 'no visible crack' which I've included a photo below. This plaster has been there a long time - probably 40-50 years I'd have thought and it hasn't cracked or shown movement.

 

 

Here's a picture looking at the corner of the house before we constructed the new extension which is the outside of crack 2. Nothing significant from outside and that corner is now abutted by a deep foundation and new cavity wall.

 

 

Upstairs the new roof is supported on a series of steel (upside down) V frames with a steel ridge, so any 'spreading' forces should be limited. after discussing with the builder, we asked the SE about whether it would be a good idea to cast in place a reinforced concrete 'ring' beam along the front of the house to resist the wall from leaning out any more. The SE said it wouldn't harm, but also wouldn't be drawn on whether we should or shouldn't do it, so that's our current plan.

It doesn't feel to me like this crack has moved much in the recent past, but I'm also aware we're doing significant structural work here. Is there a common solution for holding together old buildings like this?

 

Thank you in advance.

Edited yesterday at 13:39 by lookseehear
Missed a photo

[ProDave]

I think in this case the usual treatment is tie bars through the building holding the walls together.  Often seen by a cross or round plate with a big nut on the outside of the building.

 

It would be an SE that specifies that sort of thing usually.

[saveasteading]

OK. Done that.

 

The cracks are big enough that you should tie the areas together. it will be  a heavy galvanised plate, probably bigger than the ones at the builders' merchants. Your SE should advise.

That will have to be fixed well away from the gap.

And/or bars. into the coursing.

 

I may be able to find a photo of this in use.

 

It's a big gap so that has moved a lot and is out of balance.

But this type of wall can accommodate movement by self adjusting to some extent (there isn't an English word for shoogling).

I'm assuming this is approx 600 thick, with dressed stone outside, big stones inside and a core of rubble and lime mortar 

 

A wall of that constructions should not be plastered (the 50 year old stuff may be ok as not especially hard) but you need to fill the gap in dry stone walling fashion. ie with as many and as large stones as will fit, and using lime not cement.

Have a read up on how to do it the traditional (and still best) way.

 

It sounds as if it stopped moving some time ago, but I'd want to know what caused the movement. Water causing sopping ground is the usual cause.

 

3 hours ago, lookseehear said:

a reinforced concrete 'ring' beam along the front of the house to resist the wall from leaning out any more. The SE said it wouldn't harm, but also wouldn't be drawn

SE is right.  it may make no difference.

From doing the extension you will know the depth of the existing wall and the bottom detail if there is any; also the nature of the ground..  can you advise?

 

[saveasteading]

Not taken to show the bars  but their positions are visible on both walls. 

 

If I recall, these are everyday , threaded rods, squeezed into exposed beds.

[lookseehear]

8 hours ago, ProDave said:

It would be an SE that specifies that sort of thing usually.

Our SE isn't interested in specifying this - any tips for finding one that will? Am I looking for someone who specialises in old houses or should any local SE be able to assist? I'm nervous about someone over-specifying in this situation because I genuinely believe it hasn't significantly moved in the 5 years we've been here.

 

5 hours ago, saveasteading said:

A wall of that constructions should not be plastered (the 50 year old stuff may be ok as not especially hard) but you need to fill the gap in dry stone walling fashion. ie with as many and as large stones as will fit, and using lime not cement.

Have a read up on how to do it the traditional (and still best) way.

When I said plastering I meant lime plastering (lime putty hemp mix from Ty Mawr) rather than gypsum. I've also been plugging any bigger holes with a premixed lime putty mortar and stones as I've been going. In this case is there any risk of encouraging more spreading by filling the gap?

 

5 hours ago, saveasteading said:

The cracks are big enough that you should tie the areas together. it will be  a heavy galvanised plate, probably bigger than the ones at the builders' merchants. Your SE should advise.

That will have to be fixed well away from the gap.

And/or bars. into the coursing.

I get the bars from your picture - they look like they're effectively chased into slots then secured with resin? How deep are they chased in?

 

Is the plate similar to what @ProDave is suggesting? flat to the front of the house and tied into threaded bar embedded deep into the stonework? When you say 'well away from the gap' I'm not sure how that would work - for it to pull against anything it would need to go something like this wouldn't it?

 

[saveasteading]

The SE is right not to dabble in something that would need a lot of research. 

Do you live in an area with lots of these construction? Phone around. An SE with rhe experience will have standard solutions.

No resin. Simply friction. Rake out a bed. Position the bar with lime mortar keeping it in place.

We didn't have any tying or tightening like your blue annotations.

 

But you do also need to know what caused the lean outwards. Ground failure or the roof. And to restrain it from further movement.

[jfb]

Not sure my view will be the most popular here but I’m not convinced any SE will provide any useful input that can replace common sense. It doesn’t look too bad to me and it seems that were it actually be continuing to move apart that you would know about it.

If the area with the major crack were repointed properly I think it would not be especially obvious that there had been movement.

If it were mine I were I would just get some heavy duty ties embedded in the wall and make good. If you wanted to go a bit further you could also take out some stone and fit a large precast concrete lintel into the wall to help join each side of the crack.

 

just my 2 cents!

[ProDave]

What I was talking about is great long tie rods that pass right through a building front to back with a large plate or cross and a big nut on the outside if the building front and back to stop the walls moving further apart.  Take a walk round any town or village with lots of old houses and that is what those plates with big nuts are that you will see on many houses.

 

typical example (first stock photo I found on the web)

 

[lookseehear]

1 hour ago, saveasteading said:

No resin. Simply friction. Rake out a bed. Position the bar with lime mortar keeping it in place.

 

This makes sense, but there's no 'courses' like there would be with brick/block, although actually looking at the picture of the crack, the mortar lines aren't as misaligned as they could be. How deep does this need to be to be effective?

 

2 hours ago, saveasteading said:

But you do also need to know what caused the lean outwards. Ground failure or the roof. And to restrain it from further movement.

 

This house has been knocked around quite a lot in the past I think. It'd be very hard to establish beyond guesswork I think.

 

1 hour ago, ProDave said:

What I was talking about is great long tie rods that pass right through a building front to back with a large plate or cross and a big nut on the outside if the building front and back to stop the walls moving further apart.  Take a walk round any town or village with lots of old houses and that is what those plates with big nuts are that you will see on many houses.

 

Thanks for this - I'll look into it.

[saveasteading]

18 minutes ago, lookseehear said:

mortar lines aren't as misaligned as they could be. How deep does this need to be to be effective?

I can see some courses that could be used.  eg at your picture 1, it would be pointless using the course just above the hand as you will need to get past a couple of big stones to have effect.

But these rods bend. Alternatively you could use reinforcing bars of lower diameter and put into more courses.

 

Your inner skin is probably about 200mm thick. You should try to get the rod close to the middle of this.

 

If there is an area where the rods can't be placed, then that is where big plates become the solution, bolted into the structure and possibly to the return wall.

 

But get on the phone and speak to local SEs to find expertise.

 

FYI we Civil and Structural Engineers have strict codes of practice and don't just take on any job for the money. We must have expertise. In practice I've found that individuals think that way too: its not just words.

 

AND a lot of this is available in texts.

 

Another option is to speak directly to expert stonemasons who will have done this many times.  Their expertise is the stone, not foundations and roof forces, but maybe they can recommend an SE.

[Mr Punter]

1 hour ago, ProDave said:

What I was talking about is great long tie rods that pass right through a building front to back with a large plate or cross and a big nut on the outside if the building front and back to stop the walls moving further apart.  Take a walk round any town or village with lots of old houses and that is what those plates with big nuts are that you will see on many houses.

 

We had these on a building we converted into flats.  They went front to back and I think helped strengthen some timber beams internally.

 

 

[saveasteading]

1 hour ago, Mr Punter said:

They went front to back

They are tension rods preventing out-thrust. Timber beams will have the strength but will likely not be tied to the walls sufficiently.

That has been done very nicely as a design feature. I like that we can see the elements of structure.