Restricting usage of Basement

[Ernest Ho]

My rental property has a basement.   It is not habitable with low ceiling and narrow/steep stairwell.  Hence in my rehab, I have put in a door that I intend to lock and not provide access to tenant.  I understand there is no way of enforcing a waiver on the tenant to protect me from liabilities should something happen while accessing basement.  Also to note is the water heater which is located in the basement.

As landlord, am I allow to restrict access to basement?  I have already noted in rental agreement, but tenant is saying she has right to use basement.

This is a section 8 tenant. Not sure if it makes a difference.

Thanks very much for your advise.

-eh