Stone masonry, roofing and ring beam advice needed for old stone house renovation in Portugal

Hello all,
My partner and I are currently renovating an old stone house in Portugal. We have some building experience, but have never put a roof on a house and have minimal experience working with stone... so we are looking for some advice.
The current plan is to install a concrete (with the metal caging) ring beam along the top of the walls, to tie the walls together and the roof into the walls. The question is, would it be better to continue the ring beam up the inclined gable ends, in order to connect all 4 walls. Or should we knock down the top gable triangle, install a horizontal ring beam on top of all 4 walls, and then re-build the gable triangle? Or any other suggestions?
I’ve attached pictures to illustrate the condition of the gable end walls. You can see in one of the images how the very huge chimney we recently removed, perhaps put some strain on the wall and caused the crack. Whether or not we take down the gable triangles, we have some rebuilding work to do.
We’re keen to only use concrete if absolutely necessary, and as we’re in a seismic zone we’re under the impression that a concrete ring beam tying all 4 walls together and to the roof, would be the best option.
But what would you do?
Any advice greatly appreciated! 😁

I don't feel qualified to advise, but here's a link to the thread about re-roofing my place in Portugal, which has a ton of photos and might be of interest

Replacing the roof and building Burra a home

Thank you Burra Maluca !
These are great!

There is also a very useful facebook group - Building, Renovating and DIY in Portugal - which is a great source of more local advice.

Holly

Does your "some building experience" include some years, thousands of hours, building and reconstruction of this type of structure? Regardless, have you talked with and had somebody who does this kind of work (on this type of building) look this specific case? (Always best to talk with several such folks, of course. )

I don't do really old stone buildings. But my experience in wood construction (besides making my living in a past life as a residential plumber in San Francisco, I have maintained and rebuilt two 100 yr old building for the last 20 years) has been that we can all understand how each part of a building works, at least after some study, but putting the thousands of details together to fully understand the "situation" in the field requires considerable experience. And to give you the best choice means an depth knowledge of appropriate and current building technology available in your area.

I _have_ studied seismic construction for the San Francisco area and retrofitted one 80 year old building. Seismic building science takes some real study to get the basics and some real current experience to design a cost effective approach. To be effective it must be designed as a _system_ which includes many different parts of the building. I am not trying to discourage plans to make any parts you add strong, but I am noting that one strong piece does not make a building strong seismically.

You are dealing with the basic structure of the building, what holds it all up and together. The consequences of missing something important there can be extreme. So I am raising a flag here. If you do not already _know_ how to build that type of building advice from strangers on the internet is not something you can evaluate well.

Please forgive me if you are in fact experienced experts in this field. I just don't want innocent people to carry on thinking free advice on the internet will provide them the knowledge and skill that could mean the difference between a warm happy home and the house falling down. Or any of the thousand (expensive) alternatives in between. My own experience, over and over, has been that one _must_ see the building in person to hope to make any helpful recommendation AND that experience, a _lot_ of experience, makes a world of difference.


Regards,
Rufus

Thanks Rufus. I appreciate your advice.
We are certainly not experts nor do we have many years of experience in this particular type of construction. We are however keen to learn and to undergo this project ourselves. We have received the opinions of some local builders and obviously the more in-person analysis we can get, the better. I do appreciate that it is hard for anyone to give a thorough opinion based simply on photos and a description online, but I am curious none the less.

Would love to hear some other people’s thoughts 😊

Holly

Here is a pdf which comments briefly on seismic retrofitting old stone buildings. There is little/no specific technical info, but perhaps the overview it gives will help the thought process.

And I will add this link to what appears to be an in depth exploration of what you're involved in. The series of books as a whole may also be worth looking into. I studied with a similar book 30 years ago and found it excellent.

https://link.springer.com/book/10.1007%2F978-3-642-39686-1



Regards,
Rufus

So the ring beam is going to help with earthquake stability, I take it you have advise from local experienced people on that matter?
I am not convinced a chimney would cause cracking of a wall at the moment do you know for sure that was the case?
Sometimes cracks are caused by ground settlement.
If you can keep the building as whole as it came to you the better in my opinion.
Those gables cause no harm as far as I can see.

Ring beams can be reinforced concrete, timber or even steel.
I have read of  work in South America, where timber ring beams and vertical bars of steel or timber were added to earth buildings built by poor people.
The purpose being to give occupants more time to get out if an earthquake struck. It was a proven local method, and saved many lives.
The buildings still fell down, but slowly compared with an instant collapse.

What is the issue with concrete, in my opinion as a Civil Engineer, when concrete is used where it is the best material for the situation its a good use.
Some people dont like it because of the imbedded energy, but used as I described it can help mankind.

Local knowledge as Rufus mentioned is powerful.