How to demolish old stone walls safely?

Question

We are renovating an old property in France where three walls of an old stone schoolhouse (10ish meters high I'm guessing, maybe more in some places) sit adjacent to the more recent house (1950s). We need to demolish the walls for a few reasons. 1) They present a safety hazard. 2) They block the view. 3) We want to create a large terrace in its place. Two of the walls are not attached to anything, but the third wall is attached to another house--abandoned and not ours--by a kind of short stone bridge which complicates matters further. This wall is not destined for demolition, but it is, of course, attached at the corner to the long wall.

We've brainstormed a few ideas for how to do this safely.

1. Climb up a ladder, starting at the top and chiseling away at the mortar, thus allowing us to knock down the wall stone by stone. This seems dangerous and slow.

2. Attach grappling hooks and use a winch to pull down the wall. This seems more efficient and safer for the people involved but more difficult to control where the stones fall. EDIT: No longer considering this given rebound issues: 2

EDIT: Solution 3: use a hand winch and attach to the top stones with a metal band across several stones and then pull down one layer at a time.

We want the stones to fall inward to fill the void where the old foundation used to be and NOT outward risking rolling down the mountain and into other houses.

Anyone have any idea how to approach this demolition? Are we on the right track at all? Any tricks, advice, etc. you could offer?

EDIT: Many have commented below regarding the legal issues involved like protected/historical sites as well as adjacent property considerations. Thank you for thinking of these issues, but we are approaching everything legally and going through all the proper administrative channels (demolition authorization, etc.). France is super serious about these issues, and we don't dare do anything that would jeopardize our neighbors or our project goals!

Picture below is looking up towards the walls which are now covered in vines.

Answer 1

Taking down the wall safely is not the only issue. You wrote in comments:

there's no legal problem here because we own all the land surrounding the house that isn't ours, and the connection between the house and the old wall is actually on our property and not technically legal.

My perspective is that of a retired US lawyer, wholly unfamiliar with French real property law. In many legal systems, however, an activity on your own land (such as demolishing the wall) that affects or impairs your neighbors' land or structures thereon could create a serious legal problem for you. In US law, the underlying (pun!) concept is called subjacent support. Changing the land's drainage pattern could similarly affect others' property, and create similar liability.

Before you take any action on the ground, I would consult someone knowledgeable about these sorts of matters in your locality. An attorney or local notaire, or at least someone who has personal experience in real property construction and demolition. The person should not be someone who is involved in proposing, or doing, or contracting the work you want - that person has a built-in conflict of interest.

Removing the walls may be entirely doable. But doing so also may create serious and persistent problems, physical, fiscal, or both. You will be better off knowing before you act.

Answer 2

I would say you need a track drive excavator that has a bucket with a grabbing thumb.

You would use the excavator to grab and place the "debris from the old roof and 4th wall that have fallen" so that the excavator can have a stable place to operate from.

The excavator's bucket/thumb can then be used to systematically dismantle the wall.

For a better understanding of what i am suggesting you can watch this YouTube video on building a stone wall to see an excavator at work. (I am available to come to France, s'il vous plaît. I am a handy man.)

Photo from ebay.co.uk

Answer 3

The approaches below can be utilized to perform the demolition efficiently and safely.

If available, a lifting machine can let the worker access the top of wall efficiently and safely. The photo below is a "man-lift" (so called in the US), usually available through construction equipment rental companies. the equipment has varies size (length/high of reach), and working load allowance. You could pair it with a mobile crane, equipped with basket to hold and lower the removed stones to the designated location on ground. The stone can be loosened by a power chisel, then removed manually.

If the man-lift is not available locally, or is undesirable, you can erect scaffold and build working platform on it. But the use of crane is still recommended for safely and effectively removal of the stone. This approach allows more workers work together at the same time, so could be more preferable.