Building feng shui trees are considered to improve the feng shui of buildings, bring good luck and protect buildings from bad feng shui. Walnut tree is an ordinary tree, which will not affect the architectural geomantic omen.
Therefore, it is no problem that the walnut tree is taller than the house in geomantic omen, but it should be noted that the walnut tree should be avoided to be planted too close to the house so as not to affect the lighting and ventilation of the house.