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  • Writer's pictureMaria Luisa Castellanos

What is the difference between architecture & interior design? Miami residential architect explains

Updated: Sep 6, 2023

This is a remodeled townhouse in Coral Gables
Townhouse in Coral Gables remodeled by Maria Luisa Castellanos, R.A.

In residential work, what is the difference between architecture and interior design?

As a residential architect working in Miami, I can tell you there is some confusion. Some people hire the architect first, and some people hire the interior designer first.

In either case, there should be a clear line between what the architect does and what the interior designer does.

Let’s take the example of a condo or house remodeling. Who does what?

Any changes in the actual floor plan of the condo or the house that require taking down walls and putting up new ones would require the work of the architect. If the air-conditioning ducts have to be reworked, the architect will determine how the ducts are laid out. The architect is not alone in any project. He/She has a team. Normally, this team would require an electrical, a mechanical, and a structural engineer. Any changes to the electrical, plumbing, air-conditioning, or structural, would entail the work of these engineers under the supervision of the architect. Many times, if the work is only interior work and does not require changes to the structure or any interior bearing partitions, then a structural engineer will not be necessary.

When a new partition is added, it almost always entails changes to the electrical. New outlets and possibly light switches will have to be added. Sometimes ceiling changes are required. These too are designed by the architect.

Changes to the kitchen cabinetry also require the intervention of the architect. If an interior designer is involved in the project, he/she gets to pick the style of the cabinets and molding, if any. Maybe the interior designer works on the layout and determines the positions of the appliances. However, here again, the architect has to intervene to make sure the electrical coordinates with the appliances. If not, new outlets may have to be added, and these need to be reflected in the electrical drawings.

Often people want to add lighting to the living room, family room, and/or bedrooms. We have to make sure that there are enough spare breakers in the electrical panel to do this. Sometimes there’s not and the electrical engineer needs to upgrade the panel or add an additional panel. If the service does not have enough amperage, the general contractor must contact Florida Power and Light (FPL) to get the service upgraded. This is not possible in a condo, but normally, it is in a single-family residence. In a condo the owner must live with the electrical service provided, be it 100 amps, 150 amps, or 200 amps. If there is not enough amperage to add lights or an additional oven, then the additional lighting or oven is an impossibility.

If the windows or exterior doors are to be changed, the A/E team will also handle this. These changes will be in the construction documents with the wind load for each window noted by the architect or structural engineer.

Normally, when the project is designed by the architect and engineers, they will prepare the construction or contract documents that will be submitted by the owner, or his plan runner, to the city or county. These drawings, after the review and approval of the city or county, will become the permit drawings ready for the general contractor to execute.

So far, these items outlined above fall under the responsibility of the architect/engineering team. So what does the interior designer do? The interior designer gets to do a lot. He/She gets to pick all the floor finishes, the bathroom tile, the fixtures and faucets for the bathrooms, and the kitchen sink. The designer gets to pick any special wall or ceiling finishes and all the future furniture that will go into the living room, dining room, and bedrooms. He/She selects all the lighting fixtures that will go in the project. If there are any area rugs, the designer will select those. Of course, all of these items will be selected and proposed to the owner of the project. In the end, the owner will make the final decision on everything that is chosen.

If you have a residential property you want remodeled, call me, Maria Luisa Castellanos, R.A., LEED AP, principal of United Architects, Inc., to discuss your project, at 305-439-7898 or email me at


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