I was asked to paint a hall, stairs and landing recently and was also asked if I could do anything with the nasty crack at the bottom of the stairs.
I made the crack worse than it was by breaking it out back to sound plasterwork. As it was so deep, I built it up in layers of plaster and finally, polyfilla for the ‘smooth as a baby’s bum’ finish. It was important to maintain the sharp edge of the corner for a seamless look when it was painted.
