How did the plaster become bad during the winter

[cpalm]

But to get such severe frost damage as the thread starter has, something has "been done wrong".

Sure, in the TS case it's certainly that moisture primarily came in from above, I don't disagree.

But even if the wall had been covered, it's a bad idea to plaster with C-mortar so close to the ground.
There's capillary suction from the ground, but there's also splashing from the ground and vegetation around as well as snow. It might hold up for a while, but as soon as there are unfavorable conditions with rapid changes between rain and frost, it suffers.

 

[fsn]

Sure, in TS's case it is likely that the moisture primarily came from above, I'm not disputing that.

But even if the wall had been covered, it's a bad idea to plaster with C-mortar so close to the ground.
There is capillary action from the ground, but also splashes from the ground and vegetation around, and not least snow. It might hold up for a while, but as soon as there are unfavorable conditions with rapid changes between rain and frost, it takes a hit.

I have a leca wall about two meters high plastered with C. Had similar problems. Added a sheet to see what would happen and the frost damage disappeared completely. My wall stands on rock but one side is backfilled about 20cm and the ground is always wet, but I see no significant frost damage there at all.

 

[neo11]

I have a lecamur, but two meters high, plastered with C. Had a similar problem. Added a sheet metal to see what happened and the frost damage disappeared completely. Mine stands on rock but one side is backfilled about 20 cm and the ground is always wet but I see no significant frost damage there at all.

Are you sure it's not A or B mortar on the lowest 15-30 cm?
It's common to make a base with that mortar.
And then C-mortar or weaker above.

 

[jawen]

A lot of speculation

Yes, I'm putting my opinions to rest in this thread.
One cannot handle, as a professional, to discuss & argue in all threads with "all those who know best."

No wonder one doesn't bother to log in for a whole year.

 

[neo11]

Yeah, I'm putting my opinions to rest in this thread.
As a professional, you can't bother to discuss & argue in every thread with "everyone who knows best."

No wonder one chooses not to log in for a whole year.

Ok.
I agree with your opinions and expertise.
But as a professional, you must know that there
is no place in Sweden
where a base is actually plastered with C mortar.
Or where anything against the ground is plastered with C mortar.
It's plastered with A or B mortar.
Just for your information.

 

[Plupp 405730]

Yes, I'm putting my opinions down in this thread.
As a professional, one doesn't have the energy to discuss & argue in every thread with "everyone who knows best."

No wonder one doesn't bother to log in for an entire year.

With that knowledge, maybe one should just read for a year, perhaps?!?
I've often shared your views, but not in this thread...

 

[fsn]

Are you sure it's not A or B mortar for the bottom 15-30 cm?
It's common practice to use that mortar for a base.
And then C mortar or weaker above.

I am 100% sure that it's only plastered with C. Don't get me wrong, it's not that the plaster with ground contact is unaffected, but the difference when I moisture-protected the top made 90%.. you could also see that it wasn't freezing from below but rather from above.

 

[jawen]

I agree with your opinions and knowledge. But as a professional, you have to know that there is no place in Sweden. Where one actually plasters a base with C-mortar. Or plasters anything toward the ground with C-mortar. It is plastered with A or B mortar. Just as info for you.

Why should TS even have a base on like 2 layers, completely pointless.

TS has no draining bearing layer under the wall. TS also has wet soil right up to the masonry. Some parts seem to have 30 mm thick plaster. And no protection/roof to shield from the rain.

You can continue to believe that the problem was caused by TS using C-mortar.

And a slurrying with pure A-mortar wouldn't have lasted in the long run either, as the Leca & the slurrying will expand differently on sunny days, & A-mortar has no room for movement.

 

[neo11]

Yes, everything is about the roof.
If there had been a roof, then c mortar would have lasted a long time.
But in this case, when it is also a dry stone wall, A or B mortar is what should be used.
On the entire wall.
B mortar has better flexibility, but considering the ground, etc.
I would have chosen Cement mortar A.

 

[pojak]

draining bearing layer under the wall.
TS also has wet soil all the way to the masonry

If the wall were to have a roof, are there recommendations on how large the overhang should be?
Is a minimal overhang (a few mm) sufficient?

 

[neo11]

I would say at least 2-5 cm.
And all roofs must have a stop for the "raindrop."
If you have a stone roof, you saw a groove into the stone so that the drop stops there and then falls to the ground, instead of landing on the wall. If you have a metal roof, the drop stops on the drip edge.