Cladding rendered wall with slate

[TheGrockle]

Greetings

I'm planning to clad a couple of rendered exterior walls with Cornish slate. I'd welcome any tips or advice. Plenty of guidance online about roofing, but I can't find much on doing walls. Some specific questions:

Do I need to remove render or can I fix battens through render to masonry (some blockwork, some original rubble stone)?
What are best fixings and battens to use?
Can I put insulation under the slates? If so, what type/spec?
Any tips on where vertical slate meets the (slate) roof?
Ditto the bottom course, which will stop at ceiling of ground floor.

Any help very gratefully received - don't feel restricted to the above.

 

[JohnD]

I have a slate-hung wall (exposed coastal location)

The existing are on battens with slightly ventilated roofing felt behind. I can't remember if the felt is battened off the wall.

When it needs doing again, I would use Kingspan or similar to add insulation to the wall. I imagine you would get better results hacking off your old render as it will give you a bit of extra depth (the roof and gutters must overhang the slates to prevent rain getting behind). Mine are fixed with bronze washers and rivets to prevent the wind lifting them, hooked-over bronze nails and washers are also use. I believe stainless steel fixings are now more common.

I have an idea I have seen reference to external insulation that is slate- or tile-hung, probably on the Knauf website which has lots of specs and diagrams.

My ground-floor cladding changes to shiplap, as people might bump into it.

Water pours off the clad wall in storms, I think it would benefit from some kind of gutter at the bottom of the slates.

If you are fixing to a rubble wall, you might need resin injection.