Drilling and fixing for exterior rendered walls

[ian_uk1975]

Exterior walls of the house are red brick with a render finish on top (Weber monocouche, basically same as K-Rend). One wall is sandstone that's been levelled and rendered to match the rest of the house. Render on that wall is quite thick.

Need to fix some exterior wall lights and a mailbox and I'm nervous about cracking or pulling off chunks of render. Most of what I have to fix will be onto the rendered sandstone wall, which makes me doubly nervous.

Should I use hammer action when drilling, or would it be better to use regular drill through the render and switch to hammer action when through to the stone or masonry underneath?

Should I use standard Rawl plugs, or something else? Should the Rawl plug sit flush with the render, or flush with the underlying masonry? Finally, any tips on how to drill into the sandstone wall (which is, by nature, a bit crumbly and not easy to drill at the best of times) when I can't even see it.

 

[foxhole]

Start with 5mm masonry bit , no hammer, switch to hammer as required, [depends on quality of masonry bit] then open out hole with larger bit to suit whatever size plug you are using [6mm would be plenty for light fitting etc.] Plugs can go flush, hand tighten screws.

 

[ian_uk1975]

Start with 5mm masonry bit , no hammer, switch to hammer as required, [depends on quality of masonry bit] then open out hole with larger bit to suit whatever size plug you are using [6mm would be plenty for light fitting etc.] Plugs can go flush, hand tighten screws.

Thanks. Flush with render or flush with underlying stonework/brick?