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I believe you mean Carbon Monoxide detection, not Carbon Dioxide. Yes, the landlord must provide such a a device per Tex. Hum. Res. Code Ann. § 42.060, but this is limited to the following: day-care centers, group day-care homes, and family homes.
Family home is not what you think, however. "Family home" means a home that provides regular care in the caretaker's own residence for not more than six children under 14 years of age, excluding children who are related to the caretaker, and that provides care after school hours for not more than six additional elementary school children, but the total number of children, including children who are related to the caretaker, does not exceed 12 at any given time. The term does not include a home that provides care exclusively for any number of children who are related to the caretaker.
As such, technically, a Carbon Monoxide device is not mandatory for leases unless they fall under the above.
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