if was rented as a one bedroom AND there is a clause barring you from subleasing then that would stop you. if there is no clause barring a sublease, then you are witin rights to have a roommate. if the LL wont provide a door, then you can provide one yourself.
Unless the lease says they can, they can't simply increase the rent based on multiple people. The rent is for the place , not per person.
Whether or not "everyone uses it for two people," your lease not only has just you on it, but it probably also specifies that the tenancy is just for one person, which means you need the landlord's consent to bring in a roommate and can expect to be charged more for a 2nd person. Two people create twice the wear and tear, use twice as much electricity and water, etc. as one person does.
The door has nothing to do with it, that's a separate issue, and you can certainly ask for the door, which should be there, and the fact that it's expensive is not an excuse not to replace it.
A door probably wouldn't be considered a health and safety issue so that you could use the "repair and deduct" remedy, so you'll just have to make the request, and if the landlord refuses, you could get your own door then sue the landlord in Small Claims court for reimbursement.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
San Francisco has a rent control ordinance that probably governs this situation. I am in Los Angeles and not an expert on San Francisco rent control. It is possible that the landlord would be breaking the law by raising your rent, or raising it by a certain amount, but you need to contact the City (or a local tenant's rights attorney) to answer this question specifically.
As to the door, he has to fix it. It's his responsibility. If the cost of a new door will not exceed your rent, you can have it repaired yourself and deduct the cost from the rent. (NOTE however, that doing so MIGHT cause the landlord to try to evict you. It's probably safer to fix the door yourself and sue the landlord in small claims court for the cost.)
he following is a direct qute from the S.F. Rent Board's website,
"The Rent Board Rules and Regulations prohibit landlords from charging more rent solely for additional occupants, including a newborn child. This constitutes an unlawful rent increase, even if the lease or rental agreement provides for the additional charge. Since the Ordinance provides that tenants cannot waive their rights under the Ordinance, any agreement to pay such additional rent is void as contrary to public policy. Tenants who pay additional rent for additional occupants may file a Tenant Petition to void the increase and obtain a refund of the overcharges.
If a landlord experiences an increase in the costs of operating the building due to additional tenants, the landlord may file a petition for a rent increase based on an increase in operating and maintenance expenses. A landlord may also file a Petition for Approval of a Utility Passthrough if costs for gas and electricity increase.
To receive a copy of the tenant or landlord petition forms, you can fax them to yourself through our Fax Back system by calling 252-4660 or visit our website at www.sfgov.org/rentboard. The forms are also available at our office.'"