Here at Zacks, we focus on our proven ranking system, which places an emphasis on earnings estimates and estimate revisions, to find winning stocks. But we also understand that investors develop their own strategies, so we are constantly looking at the latest trends in value, growth, and momentum to find strong companies for our readers.Looking at the history of these trends, perhaps none is more beloved than value investing. This strategy simply looks to identify companies that are being undervalued by the broader market. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.On top of the Zacks Rank, investors can also look at our innovative Style Scores system to find stocks with specific traits. For example, value investors will want to focus on the "Value" category. Stocks with high Zacks Ranks and "A" grades for Value will be some of the highest-quality value stocks on the market today.One company to watch right now is Beacon Roofing Supply (BECN). BECN is currently sporting a Zacks Rank of #1 (Strong Buy) and an A for Value. The stock is trading with a P/E ratio of 12.75, which compares to its industry's average of 21.33. BECN's Forward P/E has been as high as 17.80 and as low as 4.55, with a median of 13.43, all within the past year.We also note that BECN holds a PEG ratio of 1.09. This metric is used similarly to the famous P/E ratio, but the PEG ratio also takes into account the stock's expected earnings growth rate. BECN's PEG compares to its industry's average PEG of 1.70. BECN's PEG has been as high as 1.34 and as low as 1.08, with a median of 1.22, all within the past year.Value investors also frequently use the P/S ratio. This metric is found by dividing a stock's price with the company's revenue. Some people prefer this metric because sales are harder to manipulate on an income statement. This means it could be a truer performance indicator. BECN has a P/S ratio of 0.39. This compares to its industry's average P/S of 0.8.Finally, investors should note that BECN has a P/CF ratio of 8.74. This data point considers a firm's operating cash flow and is frequently used to find companies that are undervalued when considering their solid cash outlook. BECN's P/CF compares to its industry's average P/CF of 15.41. Within the past 12 months, BECN's P/CF has been as high as 10.36 and as low as 2.85, with a median of 7.73.These are only a few of the key metrics included in Beacon Roofing Supply's strong Value grade, but they help show that the stock is likely undervalued right now. When factoring in the strength of its earnings outlook, BECN looks like an impressive value stock at the moment.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Beacon Roofing Supply, Inc. (BECN): Free Stock Analysis Report To read this article on Zacks.com click here.