Real Estate Operations
Leasing
As of June 30, 2020, our real estate portfolio was comprised of 32 operating properties, which we refer to as our operating properties, and 3 redevelopment properties, which we refer to as our redevelopment properties, that are in the process of being redeveloped, or are completed but not yet stabilized. We collectively refer to our operating and our redevelopment properties as our owned portfolio. Our 32 operating properties were approximately 84.5% leased as of June 30, 2020, a decrease from 87.6% leased as of December 31, 2019. The 3.1% decrease in leased space was a result of the impact of lease expirations and terminations, which exceeded leasing completed during the six months ended June 30, 2020. As of June 30, 2020, we had approximately 1,476,000 square feet of vacancy in our operating properties compared to approximately 1,175,000 square feet of vacancy at December 31, 2019. During the six months ended June 30, 2020, we leased approximately 324,000 square feet of office space, of which approximately 158,000 square feet were with existing tenants, at a weighted average term of 6.1 years. On average, tenant improvements for such leases were $22.91 per square foot, lease commissions were $7.85 per square foot and rent concessions were approximately four months of free rent. Average GAAP base rents under such leases were $31.28 per square foot, or 10.3% higher than average rents in the respective properties as applicable compared to the year ended December 31, 2019.
As of June 30, 2020, our three redevelopment properties included an approximately 130,000 square foot redevelopment property known as 801 Marquette in Minneapolis, Minnesota, an approximately 213,000 square foot property known as Blue Lagoon in Miami, Florida and an approximately 62,000 square foot property known as Forest Park in Charlotte, North Carolina. Given the length of the redevelopment and lease-up process, these properties are not classified as an operating property until, in some cases, years after we commence the project.
The redevelopment at 801 Marquette was substantially completed at the end of the second quarter of 2017 and is in the process of being leased up; however, it is not stabilized. As of June 30, 2020, we had leases signed and tenants occupying approximately 37.0% of the rentable square feet of the property. We expect to incur redevelopment and lease-up costs of $29.6 million, of which we had incurred approximately $23.1 million as of June 30, 2020.
The redevelopment of Blue Lagoon commenced in December 2018 following the maturity of a lease with a major tenant that occupied 100% of the property. On September 13, 2019, we entered into a lease agreement with a new tenant with an initial term of 16 years for approximately 156,000 square feet, or 73.1% of the property’s rentable square feet. We expect to incur total restoration, redevelopment and lease-up costs of $39.6 million, which include work on the roof of the building, costs to make the space suitable for multiple tenants and to increase parking at the property. As of June 30, 2020, we had incurred approximately $13.3 million in total redevelopment costs. We anticipate completing the redevelopment by the end of 2020.
The redevelopment of Forest Park commenced in January 2019 following the maturity of a lease with a tenant that occupied 100% of the property through December 31, 2018. We expect to incur total redevelopment and lease-up costs of $5.7 million, which include interior work to make the space suitable for multiple tenants. As of June 30, 2020, we had incurred approximately $1.1 million in redevelopment costs. We completed the redevelopment during the three months ended June 30, 2020. We have a lease with one tenant for approximately 22,000 square feet or approximately 35.6% of the total rentable square feet, for an initial term of 11 years.
As of June 30, 2020, leases for approximately 1.8% and 9.0% of the square footage in our owned portfolio are scheduled to expire during 2020 and 2021, respectively. As the third quarter of 2020 begins, we believe that our operating properties are well stabilized, with a balanced lease expiration schedule, and that existing vacancy is being actively marketed to numerous potential tenants. While leasing activity at our properties has continued, we believe that the COVID-19 pandemic and related containment and mitigation measures may limit or delay new tenant leasing during at least the third quarter of 2020 and potentially in future periods.
While we cannot generally predict when an existing vacancy in our owned portfolio will be leased or if existing tenants with expiring leases will renew their leases or what the terms and conditions of the lease renewals will be, we expect to renew or sign new leases at then-current market rates for locations in which the buildings are located, which could be above or below the expiring rates. Also, we believe the potential for any of our tenants to default on its lease or to seek the protection of