Homeowners with a few hundred extra bucks to spend on a room makeover can be excused if they're tempted to spend spare cash on materials. But hold the phone, interior designers say. The more prudent investment may be to hire someone who can tie the loose ends together for a project worthy enough to grace magazine pages.

Design professionals press a case that for a few dollars more, homeowners should at least talk with a designer in planning stages so their result isn't a mishmash of competing looks and decor. Some designers think their influence should be on par, if not more so, with that of other project contractors.

"Some of my best work is when I talk to clients before their project to work through every phase from a design standpoint," said Nancy Barsotti of New York. "Even if it's only a few hours, this avoids design errors that take away from the project."

With single room re-dos routinely costing tens of thousands of dollars, Barsotti and other American Society of Interior Design members contend homeowners should see this as money well spent.

Mindi Dickinson, a Des Moines designer, is familiar with customers who consider only the dollar signs. Yet, as she tells the design-challenged among her customers, "you can't afford not to use me. The big picture ought to be 'how does this all fit together?'" Dickinson said her $75 per hour consultations help people "prioritize materials, so they could go ahead and splurge on granite countertops but scrimp on other items."

According to Bureau of Labor Statistics estimates, there are more than 60,000 interior designers in the United States, about one-third of whom are self-employed. As such, they take work as it comes along, typically a mix of hourly work and start-to-finish projects.

The American Society of Interior Design reports more than half of members bill by the hour, so clients are free to choose the time a designer is on the job. To Susan Broll of Seattle, the end goal goes beyond an attractive final result. The challenge is to design to fit the way clients really live rather than how they feel they should live. Many customers, she said, want a room straight out of a magazine when it would be ill-suited to their daily style.

"They see what's in magazines and they start to fantasize," said Broll. "If it's a kitchen job, do you normally pre-heat ready to eat meals or go all out to prepare chef food? Being able to pull that lifestyle indicator out of someone, that's the key," she said. An established designer, Broll bills at $100 per hour.

Many designers regard themselves as de facto project managers who must not only nudge homeowners to make decisions but ride herd over workers to make certain the details are done right the first time.

From Broll's perspective, her charge as the eyes and ears of clients is to "keep the job rolling along, and that saves everyone money." She is more than willing to play hardball on behalf of clients and her own view of design esthetics. Contractors are used to "building things one way or they do it the way they want, so we have to be quality control advocates for the client," she said.

Dickinson's worst nightmare: clients who won't make decisions. "When you build a house or remodel a room, everything builds from one thing to the next," she said. "You have to help people make up their minds, and then things can move forward."

Both Dickinson and Broll offered these suggestions if you contemplate the use of an interior designer:

* Consult with the designer as you plan your project. It's okay to hire a designer for a few hours if need be.

* Have a rough budget in mind, but hold off on a final figure until the designer presents product options and prices.

* Be prepared to prioritize products or design themes once a final budget is presented.

* Avoid making changes during construction. This can result in expensive change orders or construction delays.

* Make sure your building contractor is in tune with the design and building needs of the designer.

An interior professional can coordinate design details for attractive results.