Cal. CIV § 1941.2

(a) No duty on the part of the landlord to repair a dilapidation shall arise under Section 1941 or 1942 if the tenant is in substantial violation of any of the following affirmative obligations, provided the tenant’s violation contributes substantially to the existence of the dilapidation or interferes substantially with the landlord’s obligation under Section 1941 to effect the necessary repairs:

(1) To keep that part of the premises which he occupies and uses clean and sanitary as the condition of the premises permits.

(2) To dispose from his dwelling unit of all rubbish, garbage and other waste, in a clean and sanitary manner.

(3) To properly use and operate all electrical, gas and plumbing fixtures and keep them as clean and sanitary as their condition permits.

(4) Not to permit any person on the premises, with his permission, to willfully or wantonly destroy, deface, damage, impair or remove any part of the structure or dwelling unit or the facilities, equipment, or appurtenances thereto, nor himself do any such thing.

(5) To occupy the premises as his abode, utilizing portions thereof for living, sleeping, cooking or dining purposes only which were respectively designed or intended to be used for such occupancies.

(b) Paragraphs (1) and (2) of subdivision (a) shall not apply if the landlord has expressly agreed in writing to perform the act or acts mentioned therein.