A friend recently asked me to recommend a contractor. A simple request but not a simple answer. Was she remodeling a house or adding a light fixture? Putting up shelves or tearing down walls? Did she need a new roof, a new water heater or a new kitchen countertop? Basically, did she need a general contractor, a specialty contractor or a handyman?

There are three main classifications of licensed contractors: Class A is a general engineer who has specialized knowledge and skill. While most homeowners will never require such expertise, many may call on a Class B general building contractor. A general contractor is involved in construction that requires two or more other tradespersons such as an electrician, painter, tile setter and plumber. These trades are enumerated in Class C categories. For example, an electrician has a C-10 license, a tile contractor C-54, a painter C-33 and so on.

These Class C contractors are specialty contractors, more commonly known as subcontractors. A handyman does not have to be licensed but can be extremely appreciated by homeowners who have typical odd jobs around the house.

Titles also apply to interior designers. There are specialty certifications in kitchen and lighting design, for example. My degree defines me as an “architectural interior designer” although industry labels are presently being renamed.

There is also a difference between designers and decorators. Designers have attended accredited institutions, passed proficiency exams and have earned a degree over a two-to-four-year period.

They are usually taught by practicing designers and architects who bring practical experience to the classroom. The curriculum includes space planning, fabric science, color theory, creating blueprints with electrical, plumbing and mechanical plans, and hand-drawing 3-D perspectives.

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It even includes a yearlong course covering a 3,000-year history of design and architecture — knowledge that continues to enhance and elevate my designs even after 27 years. I was also fortunate enough to have a bonus course in landscape design taught by a landscape architect.

Designers are also decorators. If I’ve designed a space from its beginning, I’ve probably had these finishing touches, these decorations, in mind all along. But if I’m asked to spruce up, pull together or update an existing space, then I get my inspiration from the clients themselves and the surrounding elements.

While there is naturally some crossover in knowledge, good contractors and designers have honed in on their specific disciplines and have kept up with current events in their individual industries. Contractors know of the latest building codes and of new or improved building materials and equipment. Designers know of hot trends, and from experience, know which ones will last. They also have access to furnishings, product and techniques not seen on the Internet or in retail stores.

Not all home improvements need a designer or contractor, of course. But for those that do, hopefully the different types of help available have become a little clearer. In addition to licenses, experience and expertise, you should feel comfortable with the people you’re inviting into your home and have a sense of trust and confidence in their abilities and their integrity. When your interests are their priorities, you have a good match.

Patti L. Cowger is a Napa-based interior designer and owner of PLC Interiors. For information about her design services, visit her website at plcinteriors.com; call 707-322-6522; or email plcinteriors@sbcglobal.net. Demystifying Design appears every other Saturday.