Half the houses in the valleys are dashed, and most of that dash has been on a long time. We do three things with it. We put fresh dash on where that is the finish you want, we patch and match existing dash where a section has come away, and we take it off and replace it with a modern render where you have had enough of it.
There is no right answer between those. It depends on the house, the street and what you want it to look like in ten years.
Patching is priced by the area and how well it has to blend. A full re-dash is priced like any other render job, on elevations and access. Removing old dash is the one that varies most, because you do not know what is behind it until it comes off.
The survey is free and we will tell you honestly which of the three we would do on your house. Where we are taking old dash off, the quote covers making good what is underneath, so you are not left with a bill for a wall we uncovered.
Usually close enough that you have to know where to look. Matching depends on finding stone of the same size and colour, and on how weathered the existing wall is. We will be straight about how good a match you are likely to get before we start.
Almost always water. Once moisture gets behind the basecoat it pushes it off the wall, and the dash comes with it. Patching without fixing where the water is getting in just moves the problem along the wall.
Plenty of people do. A silicone or monocouche render over a properly prepared wall gives a cleaner modern look and is easier to keep. It costs more than patching, so it depends how much dash you have left and how you feel about it.
Not in itself. Sound dash sheds water perfectly well. The trouble starts when it blows and starts holding water against the wall instead.