We had a strong second quarter of fiscal 2021, with 10% net sales growth as demand and business activity remains favorable.
Infiltrator once again exceeded revenue expectations with 63% sales growth in the second quarter.
In the residential end market, legacy ADS sales increased 15% this quarter.
About 1/3 of the Infiltrator sales are related to repair and remodel, and at ADS, the repair and remodel exposure is covered through our retail and national accounts.
The company's exposure to the residential market has increased to 38% of domestic sales compared to 28% at this time last year.
Still, the agricultural sales team has had a great first half of fiscal 2021, with sales up 14% year-over-year.
International sales increased 3%, driven by double-digit growth in our Canadian business.
Based on this strong demand and our desire to more fully capitalize on opportunities in our core markets, we are stepping up our capital investments, which we now expect will total between $80 million and $90 million for this fiscal year.
Brian has 25 years of successful product management experience, and we're excited to have him join our team.
Adjusted EBITDA margin increased 820 basis points overall with a 640 basis point increase in the legacy ADS business.
Net sales increased 10%, with 4% growth in our legacy ADS business plus 63% growth in our Infiltrator business.
Sales growth in the legacy ADS business was led by a 15% sales growth in the residential market, which remains robust.
From a profitability standpoint, adjusted EBITDA increased $56 million or 47% compared to the prior year.
Adjusted EBITDA for the legacy ADS business increased $33 million or 35%, with strong performance from our sales, operations, procurement and distribution teams.
Infiltrator's adjusted EBITDA increased $21 million or 86%, benefiting from strong demand, favorable pricing, lower input costs, productivity improvements as well as our synergy programs.
Our free cash flow increased $112 million to $257 million as compared to $135 million in the first half of fiscal 2020.
Our working capital decreased to right around 20% of sales, down from 22% at this time last year.
Further, our trailing 12-month pro forma leverage ratio is now 1.5 times, slightly below our target range of two to 3 times leverage.
We ended the quarter in a very favorable liquidity position as well, with $204 million of cash and $339 million available under our revolving credit facility, bringing our total liquidity to $543 million.
Based on our performance to date, order activity, backlog and current market trends, we currently expect net sales to be in the range of $1,790,000,000 to $1,840,000,000, representing growth of 7% to 10% over last year; adjusted EBITDA to be in the range of $495 million to $515 million, representing growth of 37% to 42% over last year, and we expect to convert our adjusted EBITDA to free cash flow at a rate of around 60% for the full year, driven by our strong results as well as the investments we just discussed.

Summary:
Based on our performance to date, order activity, backlog and current market trends, we currently expect net sales to be in the range of $1,790,000,000 to $1,840,000,000, representing growth of 7% to 10% over last year; adjusted EBITDA to be in the range of $495 million to $515 million, representing growth of 37% to 42% over last year, and we expect to convert our adjusted EBITDA to free cash flow at a rate of around 60% for the full year, driven by our strong results as well as the investments we just discussed.