An easy way to reinforce the stairs
Most stairs will come lose at one point. An easy way to fix the stairs is to run a new wall-string support under the original wall string. The brickwall must be sound ( strong ) in order for the new support to be effective, otherwise – a new post must be installed. (this means – removal of the floor boards, attaching the new post to the wall and joist work, etc)
This method of stair repairs is not an elegant one, but it is very efficient and in most cases will not cost more than £500 including the materials. If you have a gap between the staircase and the wall, it is a bit more complicated.It’s best not to try to screw the wallstring back to the wall, unless the whole staircase can be pushed back into the original location.
You can read more about fixing staircases here :
If your staircase is not safe – do not carry furniture or anything heavy on the stairs. Also, avoid having more than one person on the stairs – at one time. Then get a carpenter or a builder to fix it.