I think that wood furniture doesn't represent the element wood for elemental purposes. However, if it worries you, then you probably wouldn't want to add metal because that would create a clash between the wood and metal.
Instead what you would want to do is add the fire element, preferably in the color red for safety purposes. This way the fire will reduce the wood and at the same time enhance the earth. This is the natural order of things. Generally we want to remedy the domination cycle with the reductive cycle.
