Before you start, make sure you clean the wall thoroughly using sugar soap and water. This will help the timber boards stick to the wall properly.
Measure the height of the wall and use the spirit level to mark a line down the middle. Now measure the width of your wall and mark a line across the middle. This will allow you to evenly lay your timber-look boards on the wall.
Using your wall measurements, mark and measure up the boards to fit. Use the utility knife to cut the boards and break them cleanly with the set square. Remember, you need to stagger the lengths of the boards so that you don't have a straight line of wood seams running across the wall.
Use the scraper to apply the adhesive to your trowel. Then spread the adhesive evenly onto the wall, starting at either side of the line that runs down the centre of the wall. Only apply the adhesive to the area where you are about to stick one of the timber-look boards.
Take the first board and place it flush with the cornice at the top of the wall. Make sure it is also flush with the line running down the centre of the wall. Push the board onto the adhesive.
Repeat the process of applying adhesive and sticking the boards to the wall. Continually check to make sure they are straight. Use a cloth or wallpaper smoother to help press the boards onto the adhesive.
After you have stuck all your full-width boards to the wall, you may need to cut a board lengthwise to fit into the corners. Measure the width of the gap between the board and the wall. Mark this distance on the length of a board and use a utility knife to cut it. Apply adhesive to the wall and stick the board to it.