It depends on the terms of the lease. If under the lease you are renting the full yard, then no--the landlord cannot develop it into a condo during the effective period of that lease, because the lease gives you possession of the yard. On the other hand, if the lease does not include some or all of the yard, then the landlord could do as he/she likes (as the property owner) with the rest. If the lease does not clearly state what part of the yard you are renting--e.g. it simply says, for example, that you are renting a single family home at 38 Madison Street--the courts would typically interpret that to mean that you are leasing the entire property and not just the home, because normally when one leases the entirety of a single family home, one leases the yard(s) as well. In this case, if the landlord tried to press ahead with condo development, you would have a good chance of prevailing if you brought a lawsuit to stop him/her. However, if the lease does clearly state that you are not renting all or some of the yard, courts will enforce that lease term and let the landlord do as he/she wills with the part you are not renting.