Actions arising out of death or injury caused by defective or unsafe improvements to real property.

Except as provided in subsection (b), any action — to recover damages for — personal injury, injury to real or personal property, or wrongful death, for contribution or indemnity which is brought as a result of such injury or death, shall be barred unless in the case where injury is the basis of such action, such injury occurs within the ten-year period beginning on the date the improvement was substantially completed, or in the case where death is the basis of such action, either such death or the injury resulting in such death occurs within such ten-year period. For purposes of this subsection, an improvement to real property shall be considered substantially completed when — it is first used, or it is first available for use after having been completed in accordance with the contract or agreement covering the improvement, including any agreed changes to the contract or agreement, whichever occurs first. The limitation of actions prescribed in subsection (a) shall not apply to — any action based on a contract, express or implied, or any action brought against the person who, at the time the defective or unsafe condition of the improvement to real property caused injury or death, was the owner of or in actual possession or control of such real property, or any manufacturer or supplier of any equipment or machinery or other articles installed in a structure upon real property, or any action brought by the District of Columbia government.