DESIGNING A COMMERCIAL BUILDING

DESIGN A COMMERCIAL BUILDING

What does it take to design a commercial building? As a Miami architect, let me explain.

Size of lot

The size of the lot is also important. For a large commercial building, say an office building where you are going to need a parking garage, in the city of Miami, you are going to need a triple lot. A standard lot in the city of Miami is normally around 50’ wide by 100’ deep. These dimensions can vary, but this is a good starting point. On anything smaller than 150' in width, it will be very difficult to put a parking garage with various levels. There just will not be enough space to get the ramps in. In the county or other municipalities where the Miami 21 Zoning Code restrictions do not apply, you may be able to get a two-story parking lot in a smaller space, but this requires two entrances and exits which the city of Miami may not allow. At one point a person came to my office because he was contemplating building a high-rise on a 50’ x 100’ lot. I had to explain that with the parking requirements of the city of Miami, this was not going to happen. So no matter if a real estate agent tells you that the zoning is T6-8 and that you can build up to 8 stories, this is not true if you cannot get parking on the site or can arrange for nearby parking.

What are the uses of the building?

Next, we need to determine the uses for the commercial building. Will it be an office building, a mixed-use building, a school, a shopping center, will it be a retail shop, a hotel, a health care facility, or what? How will we enter the building, how many entrances will it have? How will we orient it on the site?

Orientation

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Orientation can be very important, but sometimes there is only one way the building can be oriented due to the parking requirements and zoning parameters. Usually, if the building has views, we need to work with the best views for the public areas and use the back of the building for the trash, A/C units, loading dock, etc. Whenever we can, we want to orient the building to take advantage of the best sunlight. An eastern orientation gives us great natural light in the mornings. Southern exposure gives us direct sunlight at noon. Western exposure is the sun at the end of the day, which in a climate like Miami, is not very desirable. This is the hottest part of the day and the sun casts long shadows at that time. Normally, the northern exposure has very little sun, especially during certain times of the year. Indirect light comes from the north but no direct light. Glazing on the north side of the building can be utilized here to allow indirect light to come into the building.

With the client we need to establish the “program”. The program is often already prepared by the client and given to the architect. However, there are times when the client really has no ideas of what he wants or needs in the way of spaces. See the sample program below:

The Program

Sample Program for a Small Office Building with Retail Below

Sometimes these programs are simple like the one above, or they can be very complicated depending on the number of rooms required and the hierarchy of the organization.

Studying the Zoning Code

Once we establish the orientation of a building, we need to study the zoning code in depth. The building is going to have to fit within the parameters of the code. There is normally a front setback, side setbacks, and rear setbacks. They may vary if the building is on a corner lot. Then, there may be a maximum footprint or lot coverage, and the maximum square footage of area on all floors. There may be a maximum height or a maximum number of floors. The city of Miami code, Miami 21, gives some bonuses for additional floors under certain circumstances.
We also need to study where to provide vertical circulation. This would mean at least two sets of stairs and the number of elevators depending on the height of the building. With more floors, there is a need for more elevators. All of these factors must be taken into account in order to design a building. None of these can be overlooked. The zoning code must be met but also functional aspects must be met. For example, a twelve-story building could be designed with one elevator, but it would not be functional.

Parking

If we are talking about a building that is on a podium that includes a multi-story garage, the width and length of the building at that level are very important. Each municipality and the county have different standard sizes for parking spaces and transit aisles. But a good standard is 9’ x 18’ parking spaces with 22’ to 24’ deep transit aisles. So, in a double-loaded parking lot, we would have parking spaces on each side and the transit aisle for two directions in the middle. This would give us a 58’ to 60’ width. If we can span this without interior columns, it would give us a very clean parking lot for navigation.

Then, if we double this to 120’ plus the columns in between and the walls at the end, we can create a parking garage on the bottom floors. A very important concept to remember is that the allowable buildable area is normally related to the number of parking spaces in the building. The more parking spaces, the more square footage is allowed. This is common to most zoning codes in Miami.

Mechanical Systems

The mechanical systems in the buildings must be decided. Most buildings today used some type of air-conditioning system. Split systems and chiller systems have been the standard in commercial buildings for years. The chiller system, however, is only for very large buildings. Today, more people are turning to VRF, variable refrigerant flow. It uses refrigerant as its medium to heat and cool. It operates like a ductless mini-split system. This allows for the control of individual zones. Whichever system is going to be used, it needs to be established early in the design process so that space is allowed for it in the floor plans. Loading and unloading areas also need to be established in large buildings. An area in the parking lot or on the bottom floor which is outside must be established for trash and recycling.

Building Functions

Once we have these support spaces and parking areas designed and know where the stairs and elevator(s) are going to be positioned, we must deal with the actual building functions. We need to go back to the program and decide on how are going to arrange the interior spaces. In the example above, how do we orient the retail areas? How are we going to arrange the office spaces? Where do we put the toilet areas? Then, when we have a preliminary designed floor plan, we need to look at the exterior elevations. You want an attractive building that people will want to enter. You need to decide on the storefronts and windows. Will the building have a parapet? Will the parapet hide the A/C units if you put them on the roof? Will the stairs and elevator(s) be seen from the outside? All of these enter into the final aesthetic design of the building.

Engineering

Once the preliminary design of a building is established, the engineers must be brought in to design their aspects of the building. A commercial building will normally require a structural engineer, a mechanical engineer, an electrical engineer, and a civil engineer. The structural engineer will design the structure – the walls, the footings, the floors, and the roof. The mechanical engineer will design the air-conditioning ducts and select the A/C system and units. He will also design the plumbing. The electrical engineer will design the entire electrical system including the lighting, and the civil engineer will design the drainage for the parking and connect the plumbing from the building to the street. Every one of these people has a very important role to play. None of these systems are expendable and they have to work correctly. So, a good team of engineers is a great asset to an architect and the owner of the building.

Construction Documents

Once the design is established and all the engineering systems selected, the architect and engineers bring this project into reality by producing what is called, “Construction Documents”. These are the drawings that will show how all the systems are laid out and tied together. There will be plans, sections, interior elevations, and details, many of them. On large or government projects, sets of specifications are often written to establish the materials that are to be used on the project.

After all the Construction Documents are completed, the architect turns over the plans to the owner or a plan runner for him to take the plans to the building department for review and approval. At the same time, the construction documents are given to multiple contractors to bid on the work. The best way to do bidding is to pre-qualify the bidders and then establish a date and time when all the bids will be opened publicly. This allows all the bidders to know who the low bidder was and the one who won the bid. Although it is not a requirement that the low bidder be given the job, if all the bidders are pre-qualified, and the low bid does not appear to have an error in the bid because it was so much lower than the rest, then it is common courtesy to give the lowest bidder the job.

Once the plans are approved by the building department and you have selected a contractor, you are ready to build. We will get into the construction process in another article.

You can read about hiring a contractor here.

CALL OR EMAIL

If you are interested in designing a commercial or mixed-use building in Miami, call me, Maria Luisa Castellanos, the principal of the architecture firm, at 305-552-5465 or Email me at MLC@UnitedArchs.com to discuss your exciting project ideas. I can help you clarify your ideas and develop an action plan to start your project.