Note 6—Debt

The following is a summary of debt as of June 30, 2015 and December 31, 2014 (in thousands):

	June 30,		December 31,
	2015		2014
Mortgage notes, bearing fixed interest from 4.71% to 6.58%, with a weighted average interest rate of 5.39%, and due in 2016, 2017, 2018, 2019, 2021 and 2022 collateralized by 11 properties with a net book value of $147,678.	$	90,651	$	73,706
Mortgage note, bearing variable interest of LIBOR plus 2.75% and due in 2017, collateralized by one property with a net book value of $6,122.	4,331		4,399

Total mortgage debt	94,982		78,105
$400 million unsecured revolving credit facility bearing variable interest of LIBOR plus 1.50%, due September 2018.	191,000		138,000

Total principal	285,982		216,105
Unamortized fair value adjustment	792		—

Total debt	$	286,774	$	216,105

On July 22, 2015, the Operating Partnership, as borrower, and the Trust and certain subsidiaries and other affiliates of the Operating Partnership, as guarantors, entered into an amendment to the existing Credit Agreement with KeyBank National Association, as administrative agent, KeyBanc Capital Markets Inc., Regions Capital Markets and BMO Capital Markets, as joint lead arrangers and joint bookrunners, Regions Capital Markets and BMO Capital Markets, as co-syndication agents, and the lenders party thereto (as amended, the “Credit Agreement”) which increased the maximum principal amount available under an unsecured revolving credit facility from $400 million to $750 million. The Credit Agreement includes a swingline loan commitment for up to 10% of the maximum principal amount and provides an accordion feature allowing the Trust to increase borrowing capacity by up to an additional $350 million, subject to customary terms and conditions, resulting in a maximum borrowing capacity of $1.1 billion.

The Credit Agreement has a maturity date of September 18, 2019 and includes a one year extension option. Borrowings under the Credit Agreement bear interest on the outstanding principal amount at a rate equal to LIBOR plus 1.50% to 2.20%. In addition, the Credit Agreement includes an unused fee equal to 0.15% or 0.25% per annum, which is determined by usage under the Credit Agreement. As of June 30, 2015, the current interest rate on borrowings outstanding was 1.69%.

The Credit Agreement contains financial covenants that, among other things, require compliance with leverage and coverage ratios and maintenance of minimum tangible net worth, as well as covenants that may limit the Trust’s and the Operating Partnership’s ability to incur additional debt or make distributions. The Trust may, at any time, voluntarily prepay any loan under the Credit Agreement in whole or in part without premium or penalty. As of June 30, 2015, the Trust was in compliance with all financial covenants.

The Credit Agreement includes customary representations and warranties by the Operating Partnership, the Trust and each other guarantor and imposes customary covenants on the Operating Partnership, the Trust and each other guarantor. The Credit Agreement also contains customary events of default, and if an event of default occurs and continues, the Operating Partnership is subject to certain actions by the administrative agent, including without limitation, the acceleration of repayment of all amounts outstanding under the Credit Agreement.

The Credit Agreement provides for revolving credit loans to the Operating Partnership. Base Rate Loans, Adjusted LIBOR Rate Loans and Letters of Credit (each, as defined in the Credit Agreement) will be subject to interest rates, based upon the consolidated leverage ratio of the Trust, the Operating Partnership and its subsidiaries as follows:

Consolidated Leverage Ratio	Adjusted LIBOR Rate Loans and Letter of Credit Fee	Base Rate Loans
<35%	LIBOR + 1.50%	0.50	%
>35% and <45%	LIBOR + 1.65%	0.65	%
>45% and <45%	LIBOR + 1.75%	0.75	%
>45% and <50%	LIBOR + 1.85%	0.85	%
>50% and <55%	LIBOR + 2.00%	1.00	%
>55%	LIBOR + 2.20%	1.20	%

As of June 30, 2015, there were $191.0 million of borrowings outstanding under the Trust’s unsecured revolving credit facility and $136.7 million available for us to borrow without adding additional properties to the unencumbered borrowing base of assets, as defined by the Credit Agreement. Also, the Trust had an additional $72.3 million of availability under its unsecured revolving credit facility as of June 30, 2015 which is subject to customary property underwriting standards.

Certain properties have mortgage debt that contains financial covenants. As of June 30, 2015, the Trust was in compliance with all mortgage debt financial covenants.

Scheduled principal payments due on debt as of June 30, 2015, are as follows (in thousands):

2015	$	1,109
2016	9,757
2017	40,597
2018	192,265
2019	20,081
Thereafter	22,173

Total Payments	$	285,982

For the three month periods ended June 30, 2015 and 2014, the Trust incurred interest expense on its debt of $1.9 million and $1.3 million, respectively. For the six month periods ended June 30, 2015 and 2014, the Trust incurred interest expense on its debt of $3.3 million and $2.4 million, respectively.