I’m trying to put some plugs into an interior wall in a late 1800s or early 1900s basement in the south west.
This (https://imgur.com/a/0oPVq7T) is what happened with both a 6mm diameter red rawl plug and also a Fischer duo power fixing. Plugs are about 30mm length. Basically the fixing completely pulled out due to a crumbling wall.
The material is very soft, almost like hard mud.
Can someone explain:
1. What is the brown material I’m drilling into and why can’t it hold anything?
2. How do I get a fixing into this? Do I get a much longer plug, say double the length? Will I eventually encounter hard masonry if I drill deep enough?