Exchange-traded funds offer a convenient way to invest in sectors or niches that interest you. If you'd like to add some building-and-construction-related stocks to your portfolio but don't have the time or expertise to hand-pick a few, the PowerShares Dynamic Building & Construction Portfolio (PKB -0.25%) could save you a lot of trouble. Instead of trying to figure out which companies will perform best, you can use this ETF to invest in lots of them simultaneously.

The basics
ETFs often sport lower expense ratios than their mutual fund cousins. The PowerShares ETF's expense ratio -- its annual fee -- is 0.63%. The fund is fairly small, too, so if you're thinking of buying, beware of possibly large spreads between its bid and ask prices. Consider using a limit order if you want to buy in.

This ETF has performed well, topping the world market over the past three and five years. As with most investments, of course, we can't expect outstanding performances in every quarter or year. Investors with conviction need to wait for their holdings to deliver.

Why building-and-construction-related companies?
Our global economy is on the upswing, and the housing market is recovering, in the U.S. and elsewhere. This industry is cyclical, but the cycle is in its growth phase now.

More than a handful of building-and-construction-related companies had strong performances over the past year. Hyster-Yale Materials Handling (HY -1.08%), specializing in lift trucks and aftermarket parts, has more than doubled in less than a year. In its second quarter, revenue grew 10% and operating income popped by 46%. Its backlog grew, too, by 21%. The stock yields 1.1%.

Lumber Liquidators (LL -3.80%) surged 111% and has rewarded investors handsomely, but it has also alarmed some, with a federal investigation into its flooring imports sending shares down recently. Some steer clear of any companies under investigation, but others sense a buying opportunity here or are taking a wait-and-see approach. Lumber Liquidators also faces some product safety questions. Meanwhile, with a forward P/E above 30, the stock doesn't seem to be a screaming bargain at the moment.

Oshkosh (OSK -0.80%), maker of military trucks and other things, jumped 78% and is trading near a 52-week high. The company pleased investors with its third-quarter results, as revenue grew by 2% and earnings nearly doubled, while operating profit margins also rose. A close look reveals that Oshkosh's backlog shrank significantly, though. Oshkosh is vulnerable to reductions in defense spending, but it does have a civilian business to lean on. Some are excited about its new TerraMax unmanned ground vehicle technology, and like that the company has paid down some debt and made its balance sheet healthier.

AECOM Technology (ACM 0.77%) advanced 48% over the past year, which includes a drop following its third-quarter report, which featured modest revenue growth and estimate-topping earnings. Management lowered expectations, citing weakness in Australian mining and softness in the U.S., as well. AECOM has been collecting new contracts (such as a $110 million USAID one for work in Sudan and a $19 million USAID one for work in the Philippines), but its backlog slid a little from $17.1 billion at the end of the second quarter to $16.8 billion.

The big picture
Demand for building and construction isn't going away anytime soon. A well-chosen ETF can grant you instant diversification across any industry or group of companies -- and make investing in and profiting from it that much easier.