Small wall repair, advice needed

AnnieBox

Hi all, hoping someone can help us out. We brought our first house two months ago and we have been doing it up as it needed some work doing to it. There’s one thing that we want to patch up be we really don’t know what the best way to go about it would be but we would rather try and fix it ourselves before we call out a costly tradesman.

This is the area in question: http://tinypic.com/r/2l9jpm0/8

As you can see at the bottom of the stairs, there is a large crack in the wall. I’m not sure what it’s made of but it’s hard like concrete or brick, it’s not plasterboard. The whole chunk where the crack is comes away in one big chunk if knocked or pulled however it does slot back in so we've put it back and bound it with duct tape for now (classy solution I know) but we wanted to know if there is a permanent way to fix the loose chunk back in place so we can then plaster over the cracks, fill it in and then decorate?

My partner is very handy and can do most diy things with instruction/advice, we just honestly don’t even know what to be looking for with regards to this repair but we reeeeeally don't have enough money to call out a proper tradesman to look at it :rotfl:

Any help and/or advice very gratefully received.

WobblyDog

It looks like there's plenty of surface area to work with, so I reckon pretty much anything that can be spread thinly would work.

Assuming the material on both sides is sound, I'd be tempted to stick the lump back in place with Araldyte, and then use Polyfilla to fill in the cracks,

London50

Either that or use Gorilla glue,trim any extra then Pollyfilla to smooth over