In the August issue of BUILDER, we take an in-depth look at the construction workforce as home building revs up. The focus of the report is on the availability of tradespeople because those are the folks who get the houses built.

We didn’t report on women in construction because the trades are dominated by men and women mainly work in non-jobsite functions. But as your company staffs up for the housing rebound, you also should consider how women fit into your company’s profitability. Here’s why:

The 2010 U.S. Census reveals that of people age 25 and older, 37 percent of women and 35 percent of men have bachelor’s degrees. But of those ages 25 to 29, women hold 36 percent of bachelor’s degrees compared with 28 percent of men.

According to the Department of Education, more women than men received college degrees (all levels) in every year since 1982. Overall, there are 141 women graduating with a college degree for every 100 men attaining a diploma.

But while women are snatching up degrees in record numbers, they’re leaving their jobs in droves. The Bureau of Labor Statistics says the participation rate of women in the workforce dropped from a high of 60.7 percent in 1999 to 58.8 percent today. By contrast, 72.5 percent of men are either working or looking for a job. Economists and others worry about this trend because they argue the U.S. economy needs an educated, well-trained workforce, and women are earning more of the college degrees.

What women are not earning, however, is equal pay—they still make 77 cents for every dollar their male counterparts make. So lots of them drop out of the labor pool or work part time when they start having children because child care is expensive and many firms don’t offer flexible hours or work-at-home arrangements.

This exit, even if it’s temporary, often negatively impacts a woman’s career and earnings power—and most important to you, costs you thousands of dollars. According to Investopedia, even an $8-an-hour employee who quits costs a company $3,500 in direct and indirect ways.

My best friend graduated college with honors, went on to earn an MBA, and quickly advanced in the marketing departments of several major credit card companies. Even though she earned as much as her husband, she no longer could justify the daily two-hour commute and an inflexible boss.

When her oldest daughter entered first grade, she took a job that did not take advantage of her experience or education, working less than 20 hours per week. When she decided to go back to work full time 10 years later, it took my friend two years to find a suitable position—but she’s earning $20,000 less than she did when she stopped working full time.

Likewise, my friend’s sister-in-law has a law degree, but she quit working when her first child was born. She’s now in her mid-50s and pens the occasional will.

These women are smart, highly educated, and were moving up the corporate ladder. So how could they have stayed employed? Here’s one example: When one of my staffers started having kids, she asked to reduce her hours to 32 (still considered full time) and work at home one day per week. She was one of my star employees—smart, hard-working, and easy to manage—so I agreed. I knew if I didn’t say yes, she’d be gone and I would be stuck training someone new.

Fourteen years later, she produces as much or more than a 40-hour-a-week worker in our ever-changing media company, and her performance remains top notch. She hasn’t directly told me this, but I know she sticks around because of her flexible schedule and because she’s paid well.

The bottom line is this: Many more women are graduating college than men, and women now outnumber men in the workforce. It’s expensive to hire new employees and train them; it’s much easier to keep well-trained, productive women by offering equal pay for equal work, flexible schedules, and promotions.