Horizontal cracks in an external wall

to_be_FTB

Would someone be able to advise what might be causing these horizontal cracks in the external wall? Is it something to be worried about/be proactive about? The house is about 50 years old.

stuart45

Horizontal cracks can be a sign of wall tie failure. Wall ties are normally about every 18 inches, 9 at the reveals.

to_be_FTB

Ouch... This sounds expensive... Would that be something for structural engineer to investigate? 

stuart45

There are specialist companies who do tie replacement. They can stick a camera into the cavity to have at look at their condition.
It depends on what type you have. Untitled | DIYnot Forums  If you look at the ones on the far right, these are thin butterfly ties and are too thin to lift up the masonry. The thicker twist type expand enough to do some damage when rusty.
However as it's rendered it could just be a shrinkage crack in the render.

Grizzlebeard

There are specialty companies that replace wall ties. A few thousand £££s.
Can't quite tell from photo but are there signs the render has previously been patched up in horizontal or zig zags between bricks? Danger comes if outer wall begins to bulge as outer skin takes compression load. Unless there's other weakening factors, like a chimney breast that's been removed, house won't fall down for many many years, but better sorted sooner than later.

to_be_FTB

Great - thanks! Would replacing them (if it turned out necessary) require replacing render or would they just drill some holes? And is it done from the inside of outside of the wall/house?
(Nothing was done to the walls in the last ten years, but it's not obvious to me whether there might have been any patching up done before that...)

stuart45

It's done from the outside. Old ones needs removing or isolating if the thicker twist type. You can DIY it but most people don't want to. The specialists( even though they are semi-skilled and that's being generous) have some expensive testing equipment like this Wall Tie Tester| Tension Load Test Unit | Wall tie testing kit (twistfix.co.uk)

Grizzlebeard

Nearly always an external scaffolding job, although vibrations from the heavy hammer drilling can crack internal tiles, mirrors, make stuff fall from shelves, etc, for which the companies will accept no responsibility. Your plain rendering will be made good as part of the job, but probably won't include the cost of a new coat of paint.

stuart45

When tie replacement first came out, some of the companies were making a real mess of making good the face brickwork.
Normal thing was for them to mix up a bit of red dye in and splat it into the holes leaving a load of bright red patches on the walls. 
Nowadays they get the mortar colour matched by specialist companies. 
Another problem with vibrations in the wall is shaking off some of the mortar snots in the cavity which can fall and bridge the cavity at the bottom above DPC.

to_be_FTB

Thanks for your replies - it all sounds slightly less terrifying. We will get it looked at by a specialist company and see what they recommend!