Core drill - external insulation

Gyck

Hi,

I need to drill through external insulation with a core drill and I'm checking to see if it's better to start on the external side to preserve the rendering.

Thanks,

Kev

micar

I need to do the exact same thing....I'd like to know as well.

Do you go with 100mm or 110mm core?

whizbang

If you drill from the inside, the potential spalling on the external surface of the concrete wall will dislodge a significant amount of the insulation,

Probably needing the whole wall refitted and rendered.

Ideally Drill pilot hole first, then start from outside, finish from inside.

cnocbui

Start on the outside. Whizbang nailed it.

finnyob

https://www.boards.ie/discussion/comment/119582056#Comment_119582056

Core size will depend on what you'll insert into the hole. If you're putting in air vents, be sure to check the diameter dimension of the vent first, for example.

Cuddlesworth

https://www.boards.ie/discussion/comment/119605494#Comment_119605494

I used to drill a pilot hole, draw a cirle around the hole slightly larger then I'd be drilling, run a knife around the line on the inside deep in the plasterboard, angle grinder on the outside on the render. Then start inside, drill halfway, start outside, drill halfway. If done right, no damage at all to the surfaces.