The ordinary projection of parapets, windowsills, doorposts, rainwater leaders and similar ornamental or structural fixtures may project a maximum distance of 12 inches into required yards; eaves or other such roof overhangs may project a distance of 12 inches, including any gutters attached thereto, into required yards unless the same are at least 10 feet above the natural grade beneath, in which case the permitted projection shall be 24 inches.