Williamz

It’s an internal wall between my apartment and the communal hallway, in a modern build. It seems to be the wall in the photo attached, cavity, insulation then another wall which goes onto the hallway.

Hi all, New member here, and keen DIYer. I’m looking for help with my current project. I’m installing a shotgun safe - it will be bolted into solid wood floors, which has worked fine, but then I’m bolting the back of it to my wall. I assumed the wall was plasterboard, and bought GRIP-IT plasterboard fixings, which I’m very familiar with having used them on other walls. I drilled the 25mm hole, however, found the wall was 3cm thick, followed by a cavity (1 inch), followed by some insulation. I have never seen plasterboard this thick, and can’t find anything online about such thickness plasterboard. The material is chalky like plasterboard. As I thought it was plasterboard, I then bought the GRIP-IT undercutting tool to try and carve out a channel for the product’s “wings” as the wall was too deep for standard fixings, however, this hasn’t worked - the wings don’t have space to open! That’s the reason why in the photo attached appears to have a channel/void. Could anyone please advise: 1) what building material this is? 2) the strongest way I can bolt into it? Thank you in advance! William