If such special writ of execution be for the sale of a house, building, structure, or fixture and the land, or for the sale of the same without the land, the officer shall levy on, advertise, sell, and convey the same as in other cases of land levied on for debt; and if the sale be of the house, building, structure, or fixtures alone, and the same shall have been erected or constructed and put on the land subsequently to a former encumbrance on the land, the purchaser shall acquire the same free from such former encumbrance, and his purchase shall authorize him to enter and remove such house, building, structure, or fixture from the land with reasonable dispatch; but if the house, building, structure or fixture so sold, or sold with the land, shall have been simply altered or repaired subsequently to a former encumbrance on the land, the purchaser shall acquire the same subject to such encumbrance, unless the encumbrancer consented in writing to the alteration or repairs, in which case the house, building, structure, or fixtures so altered or repaired shall be sold free from such encumbrance, and with the right in the purchaser to enter and remove the same. If the land be sold also, the purchaser shall acquire such estate therein as the owner or builder, as the case may be, had at the time the lien to enforce which the sale is made attached thereon, or at any time afterwards, subject to prior encumbrances; but buildings, structures, or fixtures erected or constructed and put on the land subsequently to prior encumbrances shall pass to the purchaser as if the sale were of such buildings, structures, or fixtures alone.