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.Of these, perhaps no stock market trend is more popular than value investing, which is a strategy that has proven to be successful in all sorts of market environments. Value investors use tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.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 value investors might notice is Owens Corning (OC). OC is currently sporting a Zacks Rank of #2 (Buy), as well as an A grade for Value. The stock is trading with a P/E ratio of 14.45, which compares to its industry's average of 21.27. Over the past 52 weeks, OC's Forward P/E has been as high as 19.95 and as low as 6, with a median of 13.90.Investors will also notice that OC has a PEG ratio of 1.32. 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. OC's industry currently sports an average PEG of 1.85. OC's PEG has been as high as 4.73 and as low as 0.57, with a median of 1.59, all within the past year.Value investors also love the P/S ratio, which is calculated by simply dividing a stock's price with the company's sales. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. OC has a P/S ratio of 1.29. This compares to its industry's average P/S of 2.03.Finally, investors will want to recognize that OC has a P/CF ratio of 9.73. This metric takes into account a company's operating cash flow and can be used to find stocks that are undervalued based on their solid cash outlook. OC's P/CF compares to its industry's average P/CF of 16.63. OC's P/CF has been as high as 9.73 and as low as 3.98, with a median of 8.13, all within the past year.These are only a few of the key metrics included in Owens Corning'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, OC 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 Owens Corning Inc (OC): Free Stock Analysis Report To read this article on Zacks.com click here.