I am converting on old fireplace hearth in a kitchen to hold a range cooker. Presently the hearth has a concrete lintel at the front which i would like to remove and replace with oak timber beam. As i want to see the beam underneath as well as in front i don't want just a false floating beam attached at the front but replace it with a large 7" x 7" oak beam. Is this allowed in the building regs? The span is approx 46".