La. Civ. Code art. 493
Buildings, other constructions permanently attached to the ground, and plantings made on the land of another with his consent belong to him who made them. They belong to the owner of the ground when they are made without his consent.
When the owner of buildings, other constructions permanently attached to the ground, or plantings no longer has the right to keep them on the land of another, he may remove them subject to his obligation to restore the property to its former condition. If he does not remove them within ninety days after written demand, the owner of the land may, after the ninetieth day from the date of mailing the written demand, appropriate ownership of the improvements by providing an additional written notice by certified mail, and upon receipt of the certified mail by the owner of the improvements, the owner of the land obtains ownership of the improvements and owes nothing to the owner of the improvements. Until such time as the owner of the land appropriates the improvements, the improvements shall remain the property of he who made them and he shall be solely responsible for any harm caused by the improvements.
When buildings, other constructions permanently attached to the ground, or plantings are made on the separate property of a spouse with community assets or with separate assets of the other spouse and when such improvements are made on community property with the separate assets of a spouse, this Article does not apply. The rights of the spouses are governed by Articles 2366, 2367, and 2367.1.
La. C.C. § 493
See HCR No 306, 2004 R.S., relative to retroactive effects.