Open crack in joints of gable end wall

[Vinoapresmidi]

Hello all, this is my first post on this site. I have bought an old farmhouse in the Pyrenees which is built of cobblestone walls. The left hand gable end is butt jointed to the front and rear walls. An open crack exists in the topmost 6ft of the two corner butt joints. That is to say, the gable end wall has moved by leaning over by the weight of the roof (the main roof beam is weak too, built circa 1860). Anyhow, there's no settlement. The lean is because the gabel end wall also formed an end wall of a barn which the farmer demolished years ago. (the barn was next to the house and shared the adjoining wall. This left the wall standing by itself as a gable end supporting the roof and butting up to the front and back walls. (I hope you can visualise this)

My question is can anyone tell me what the propername for a wall which forms the exterior wall of a house which is not joined at the corners by a quoin?

To rectify the situation I think I shall do this:

1) Put solid 22 gauge steel bar from front wall to back through floor void with threads on each end. Cap it off with an old steel cart wheel and tighten till it bights. Four bars in all along the house.
2) Build new gable end wall inside old cobblestone wall. When floor reached stop. Remove this end of the roof. Take down old cobblestone wall to same height of new wall. Level off old wall. Build up new cavity wall using old wall and continuing with new inside wall (with Ties)
3) Renew this end of roof (wood) that is.

Theory - The heavy gauge steel bars keep front and back walls up while gable end wall stripped down to 1st floor level.

Any suggestions? The cobblestone I believe is of limestone pebbles - they're quite big pebbles. Smoothed out by glaciation and from the river bed I believe.

 

[^woody^]

It's a former party wall. It does not get a new name just because it's not tied in at the corners.

For your plan, yes it's one way. We would use a structural scaffold design.

The thing with stone walls, is that they don't spread the load in the same way as bonded brick and block, so buttressing and support needs to be carefully considered by a specialist to ensure that all necessary parts of the wall are supported.