granite house walls crumbling

[meercat]

My external house walls, which are made of 18" thick granite, are crumbling and flaking. How do I repair and protect for the future.

[Perry525]

I wonder if you are wrong about the walls.
Could it be, they are not granite?
18 inch blocks are very heavy.

[meercat]

I am led to believe they are granite, the house was built in 1837.

[Perry525]

The reason I asked is that granite is very hard and lasts for years without any sign of weathering.
If the blocks are splitting due to the action of rain and freezing, it would suggest that the blocks are something else.
The main thing is to stop the blocks getting wet.
Painting them with a waterproofing silicone compound will help, or covering with, tiles, slates, cladding anything to shed the rain.

[TheDoctor4]

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