4.
Limitation on reimbursement.
No tenant may seek or receive reimbursement for labor provided by the tenant or any member of his immediate family pursuant to this section. Parts and materials purchased by the tenant are reimbursable.
5.
Waiver.
A provision in a lease or tenancy at will agreement in which the tenant waives either the tenant's rights under this section or the duty of the landlord to maintain the premises in compliance with the standards of fitness specified in this section or any other duly promulgated ordinance or regulation is void, except that a written agreement whereby the tenant accepts specified conditions that may violate the warranty of fitness for human habitation in return for a stated reduction in rent or other specified fair consideration is binding on the tenant and the landlord.
6.
Rights are supplemental.
The rights created by this section are supplemental to and in no way limit the rights of a tenant under section 6021.
7.
Limitation on liability.
Whenever repairs are undertaken by or on behalf of the tenant, the landlord shall be held free from liability for injury to that tenant or other persons injured thereby.
8.
Application.
This section does not apply to any tenancy for a dwelling unit which is part of a structure containing no more than 5 dwelling units, one of which is occupied by the landlord.
9.
Lack of Heat.
If the landlord fails to comply with the provisions of Title 14, section 6021, subsection 6, then the purchase of heating fuel by the tenant shall be deemed to be a "cost of compliance" within the meaning of subsection 2. For tenants on general assistance, municipalities shall have the rights of tenants under this subsection.