Stairs - Safe to chisel away or not?

[sizzlephizzle]

I have just moved into a new house and have found some very useful posts on DIYNot.com so a big Thank You from me to the whole community.

I currently have two issues but will put them in separate sections.

This query is that my under stairs cupboard is a utility room but the under side of the stairs is really badly plastered/cemented. Not only is it unsightly, covered in old damp and cobwebs, it also has a small lump knocked out of it allowing me to see how hollow this is.

I am therefore including pictures to get some advice as I'm a little short on ideas here.

http://www.diynot.com/network/sizzlephizzle/albums/20665

I also recorded a vid and put it on youtube to try explain better.

Any advice apreciated, thank you

Intention: make it flat all the way up.
Questions : Is this supporting the staircase or is it just a bad plaster job, trying to make it look better?

 

[ree]

Its probably plaster lath and its essentially for fire protection. Leave it alone is best advice

And do not interfere with the post on the RH side thats perched on a brick corbel.

You could PVA the soffit, and skim over it but, in time, it would hairline crack with traffic up and down the stairs. Or screw/fit plaster board over some packings and skim over.

Is this the house stairs or a basement stairs?

 

[sizzlephizzle]

House stairs. No basement for me. This utility room has a washing machine in it and the gas box. I'm unsure why fire prevention would be in place in that corner but not in the rest of the room? That may be my own stupidity.

The option of plasterboarding is esentially what I am hoping everyone suggests. Want to strip it back and get a nice sharp angle on it.

Thank you for replying, seeing everyone elses posts getting replied to made me wonder "How long till I can bump this"
Thanks!

 

[ree]

Stair soffits (the underneath) were traditionally required to have a layer of protection (typically plaster) against fire.

As i said, dont strip it out to get your "sharp angle" simply pack out the P/B fixing/furring-out pieces.