Wedi Board

I have been thinking recently about how to go about building the curved wall around the top of the spiral staircase. I spoke to the plasterer about it and he recommended using the thinner sheets of plasterboard (9mm), plenty of timber studwork, and maybe some water spray to ease the bending. He also said that it can be done as a series of straight sections to which the curve is applied using the plaster (but this takes longer, hence costs more).

I asked the builder about it the other day and he described some board that they had used on a job recently called "Wedi Board". It is designed as a waterproof backing for tiling in bathrooms (e.g. for building shower enclosures).

However, when I looked at their website I came across a board that is specifically designed for building curved structures - the WediBoard BA Construct :

The outer skin is pre-slit to make it flexible. The picture above shows the slits running across the short edge, but it is also available on the long edge. I called the company and spoke to their technical help-desk and they said it can be plastered. Before plastering you have to go over the board with a cement based adhesive to close the slits and improve the rigidity.

It is not cheap - a 2.5m x 0.6m sheet costs ~£55 which is a lot more than a 9mm sheet of plasterboard. However, that 2.5m length is an advantage because one sheet will reach from floor to ceiling, which a 2.4m sheet of plasterboard does not. This gets me away from having to make curved noggins to deal with the join. I like the sound of that !

http://www.wedi.co.uk/home.php

My only worry now is bending 3/4 inch thick ogee skirting board.......