How to close/plaster a deep hole in the wall

[tellme_why]

Hi,
I want to plaster over a rather deep hole by the new boiler.
What's the best practice / building material I do need to use?
The two holes are quite deep (see pictures) and wondering whether / how I can procure some rubble and stick on the wall with rapid cement, let it dry and plaster over the next day?

What type of cement / plaster shall I use?

Many Thanks

 

[Murdochcat]

The boiler looks like it’s mounted on a wooden board - is this correct ?

 

[tellme_why]

The boiler looks like it’s mounted on a wooden board - is this correct ?

yes the wall was too messy, the installer had to put a wooden board underneath

 

[robinbanks]

Postcrete. Mix it up stiff and fill the hole with it

 

[tellme_why]

Postcrete. Mix it up stiff and fill the hole with it

thanks, do you mean no rubbles / stones in the mix?
I can only find postcrete being used for fence holes in the ground rather than on vertical interior wall?

 

[robinbanks]

It's "just add water" concrete, suitable for filling holes. It's an easy option for filling holes if you've only limited experience working with/mixing cementitious substances. You could get any similar product

 

[Eccles]

Had similar problem in bedroom of ours when we moved in. Got a tub of Wickes Plaster Skim and Repair (it does not slump), had two goes with it as hole was a bit deep - sorted!

 

[Koolpc]

Expanding foam and then plaster...