Leaning stone wall

[Foo Gee]

I'm currently renovating a stone Breton house and enjoying the steep learning curve that comes with that as well as learning a new language.

My latest problem is to do with our (we are attached to an identical house) gable end wall which has a lean. A while ago an architect said we needed to take the wall down and rebuild it because of its lean. It's about 70cm thick and has a chimney central to it. Having tried some stone walling this week where I blocked up an old doorway I realise that for me to take on the gable end would take forever so I got a mason over yesterday to have a look. He is asking me why I want to take the wall down because it's been there for a very long time and unlikely to come down in our ownership. However, he has said that it does need some pointing in a rendering to firm up all the joints and stop further movement because there currently isn't any pointing to be seen.

We need to replace the roof (rotting timbers and the crochets holding the slates have perished so the slates are all starting to slip. Therefore, the framework for the gable will need to be removed and replaced which would mean the wall would be entirely self-supporting while the new frame is made on site.

The wall is about 5m high and 70cm thick with an approximate lean of about 20cm. My priority is to be safe, my next is to keep the building as preserved as I can and my next is to save money. All three are very closely linked!

I'm afraid I can't upload any photos as my connection is so slow here.

Oh yes, and EDF are due to arrive on Wednesday to re-site the electric supply because it is currently coming in at the top of the gable so if I could save money by keeping the gable intact I fulfill one of my priorities twice over.

Thanks in advance for any opinions.

 

[Me!]

The wall is about 5m high and 70cm thick with an approximate lean of about 20cm. My priority is to be safe, my next is to keep the building as preserved as I can and my next is to save money.

I certainly wouldn't worry about a lean as slight as that as long as the wall is sound. Being 20cm out on a 70cm thick wall means that the centre of gravity even at the very top is still within the footprint of the base of the wall, so it will still be stable. I would make sure all the pointing is sound over the whole wall, and then leave it like that.

 

[88v8]

What he said.
To be sure, you might want to dig down in a very localised fashion and satisfy yourself that it has some sort of foundations.

It should be repointed in lime, as you may know, depends what skills there are available locally I guess.

Ivor

 

[Me!]

I don't know if this is the same in Brittany, but in the Poitou-Charente area it seems to be the norm to use lime for pointing the outside of external walls and cement for rendering the inside. The idea is that water enters and exits through the external breathable face, and the less breathable cement internally encourages the damp to go out rather than in. Obviously you need to decide for yourself how you want to do it, but I thought I'd mention this option incase a French builder suggests it to you.

 

[Foo Gee]

Thanks for the advice. It does make sense that the pointing in (choux in France I believe) adds the stability to the wall.
I quoted the 20cm figure that the mason gave me but that was standing in the attic and half way up the wall height. The 5 metres height is from the attic floor so the full height of the wall would be more like 7.5 metres with a width of approximately 6.5 - 7 metres and the depth of 70cm.

Looking at the wall from the outside and taking a level from much lower down the lean is much greater. The wall seems to be consistent in its lean until about 1.5 metres high where it leans much greater. I would say the lean from bottom to top is more like 50cm. From bottom to ground floor ceiling it is about 5cm (taken internally) so the lean does become greater the higher the wall goes.

I have to replace the roof because the A frames have all shifted over (possibly explaining the wall lean) and I'm now wondering whether I should possibly look at partial wall reconstruction where the lean gets greater. Again, sadly I am unable to load photos to show this so I hope my description is good enough. I'm sort of voicing out loud (well, written perhaps rather than out loud) my thoughts because it's most probably a case of remove the timber frame construction and see what happens to the wall.

Any further thoughts from the forum are greatfully received.

 

[xanthe]

We have a substantial lean on the gable end of our property.

While the surveyor had a few worries about a couple of our brick panels (we're timber framed with brick noggin - frame c.1580, noggin c.1650 onwards) having the bricks more outside than inside the timbers, he had no worries about the lean at all.

We likely had another bay that leaned over so far that it did have to be removed, but this section has leaned at the current angle for at least 2-300 years without any threat of collapse.

Here's a picture that slightly shows the lean - it's a lot worse than it looks here in reality... looking out of the top floor window is rather vertiginous.

 

[Lime]

I agree with the mason entirely.
I wouldn't bother looking for foundations, in all probability there will be none worth speaking of, the fact the wall has stood the test of time is proof enough the support is satisfactory.

 

[Penners]

I agree with the mason entirely.
I wouldn't bother looking for foundations, in all probability there will be none worth speaking of, the fact the wall has stood the test of time is proof enough the support is satisfactory.

I agree with Lime entirely.

I also agree with Me! above, that this slight lean still keeps the centre of gravity within the wall, so it's unlikely that there will be significant "outward" forces within the structure.

I would have a good repointing job done.

However, it's your wall and the final decision must be yours. If you remain sufficiently worried about it, then for your own peace-of-mind you may need to have it rebuilt.

 

[chuckey]

Question is the inner part of the wall leaning too? . If it is then your purlins are loosing their grip on the outside wall and disaster will follow. Also if the floor joist are mounted in this wall they too will be loosing their grip. Just thought I would cheer you up.
Frank

 

[steveb]

that's a good point - a 20 cm lean if the joists are only embedded 20cm into the wall could be considered a "bad thing" even if the wall is in no imminent danger of collapse..

 

[Keithj]

Good point! We had a 10cm "lean" in the studs at the back of the house, where the main cross beam holding the upstairs floor had about 10½cm resting on the stud. It was a worrying time.

 

[Foo Gee]

Thank you for the feedback, it's been very interesting to get everyone's thoughts.

I'm temporarily back in the UK so have a reasonably decent/reliable internet connection at last.

The lean is into the building and I think the comment about the purlins losing their stability is a good one. I say this because there is evidence of the purlins on one side of the timber construction having been replaced and the gable having been rebuild on that edge. It has also been pointed out to me that it looks like the roof has been widened and so the wall has been added to separately.

EDF are over this week to re-site the cable coming into the building because it is secured towards the top of the gable and we don't want any issues should there be any instability when the timber roof structure comes down. This will give us some freedom to make a decision on removing just the top part of the wall that has the most lean and rebuilding it accordingly.

I really do see that good pointing in will make the structure much more secure and will be sure to get this done. A new timber roof structure 'charpente' will also make a huge difference. Currently the 'A' frames are twisted over and in two cases the bottoms of the frames have been sawn off for some reason and large horizontal timbers joining the two 'legs' of each frame added to lend some stability.

I have dozens of photos but no account to load to but could sort out a few and email them to someone to upload if anyone is interested?

The ceiling joists are possibly safe because, if anything, the lean is pushing in against them rather than away from them.

This is one of the most interesting tasks I have had and so different from the run-of-the-mill DIY jobs that I used to do!

Again, thanks for the advice and opinions.

 

[chuckey]

On my stone built cottage the ends of the rafters are tapered and rest on the rubble infill in the walls. Its a rough old solution, and it leads to the problem that if an internal wooden window lintel requires replacing, the section of roof over the window becomes totally unsupported. If you are doing major roof works I would reccomend that a wall plate is used for the ends of the joists. That way if a window lintel requires replacing, the wall plate itself can be ackroyded up, to keep the roof in place while the work is done.
Frank

 

[88v8]

The ceiling joists are possibly safe because, if anything, the lean is pushing in against them rather than away from them.

I'd be cautious about taking them out then!!
Be rather funny if they were holding up the wall.

Ivor

 

[Foo Gee]

Don't worry, I'm not removing any ceiling joists. The house is single storey with an attic. The timber 'A' frame (Charpente) is what I will be removing and replacing.

I have added another response but it has been slotted in earlier to the topic because of approval for two posts at separate times. It details further information on the wall.

Thanks again for the responses.