Executive Vice President and Chief Financial Officer at Extra Space Storage
Thanks, Joe and hello, everyone. We had a strong third quarter, $0.01 ahead of our own internal FFO projections. While same-store revenue was generally in line with our expectations for the quarter, we did have higher than expected bad debt expense. The bad debt increase was primarily driven by lower collections from auctions. In other words, our customers' ability to pay for storage doesn't appear to have changed as much as an auction buyer's willingness to pay for auctioned goods.
We experienced outsized year-over-year growth in most of our expense line items. And I think some additional detail may provide helpful context. In the third quarter of 2021, we had same-store payroll expense of negative 9% and property tax growth of negative 4.5%, which drove total Q3 2021 expense growth of negative 4%. If we evaluate our third quarter expenses on a two-year stack, average payroll expense growth was approximately 5.2%, average property tax expense growth was 3.1%, and average total annual same-store expense grew 4.2% a year.
Turning to the balance sheet, during the quarter, we completed an accordion transaction in our credit facility, adding $600 million of unsecured debt across two tranches. We capitalized the Storage Express transaction with $125 million in OP units at an average price per share of $201.84, with the remainder drawn on the revolving credit facility. This resulted in a net debt to EBITDA of 4.6 times at the end of the quarter without the benefit of the additional EBITDA from Storage Express given the late quarter close. The revolver draws caused our variable rate debt to exceed our typical range of 20% to 30% of total debt at quarter end.
Subsequent to the end of the quarter, we swapped $200 million of our variable rate debt to reduce our floating interest rate exposure to approximately 35%. Additionally, our bridge loan balances provide a hedge against increases in variable rate debt, effectively reducing the percentage to approximately 31% of total debt. We will continue to take steps to reduce our variable rate debt further.
Our commitment to the investment grade bond market has not changed and we expect to utilize this market again once conditions normalize. As Joe mentioned, we tightened our 2022 guidance. Given the outsized growth and unique customer trends we have experienced over the past two years, we have had a wider-than-normal guidance range throughout the year to capture all of the different scenarios that we believe were possible. As we have moved through the fall, the moderation has been more pronounced than we projected at the high end. However, it was also not as severe on the low end, resulting in the tighter range.
The reduction in same-store NOI guidance is partially offset by higher-than-expected interest income due to larger bridge loan balances and higher interest rates as well as an expected later modification date of the NexPoint preferred investment. We have also increased our forecast for management fees and other income. Interest expense estimates have increased due to debt associated with Storage Express, other acquisitions, additional bridge loans and an increase in benchmark rates.
Given our total investment activity year-to-date, we have increased our acquisition investment guidance to $1.65 billion, all of which is closed or under contract. After these adjustments, we have tightened our core FFO range, which is now estimated to be between $8.30 and $8.40 per share and implied increase of approximately 21% year-over-year. We still anticipate $0.20 of dilution from value-add acquisitions in C of O stores in line with last quarter's estimate. We are having a great year and we continue to be optimistic about our ability to maintain healthy growth in 2023 as we see storage fundamentals normalizing to historical levels.
With that, operator, let's open it up for questions.