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Site Design and Unit Mix

September 1, 2002

7 Min Read
Site Design and Unit Mix

Too often, the words "site design" and "unit mix" are used in a single phrase referring to one activity or used interchangeably as if they were the same thing. This is not so. Think of site design as "site planning" and unit mix as "unit-mix formulation." Both affect the bottom line and are interrelated to some extent, but one must come before the other. In fact, these processes are based on two completely separate sets of criteria. If you consider a painting, the site-planning process determines the shape of the canvas--including the borders and how it fits into the frame--and only touches on what the picture will be by introducing certain basic shapes. The unit-mix formulation defines each of the shapes and reveals the meaning of the picture.

Site Planning

This is the first step and requires a great deal of information about zoning regulations, setbacks and other jurisdictional requirements. This is where you want to have an experienced design builder or a very good civil engineer with self-storage experience to get through the city or approving jurisdiction. I suggest using a civil engineer from the local area on your team. A local engineer who is familiar with all the current zoning regulations will save you weeks and months in getting your site plan approved.

While hacking out your site plan, some of the most important considerations are land cost, land coverage, site improvements and building layout. The key to site planning is understanding these variables and what they cost to maximize the coverage on your site.

Land cost and land coverage can go hand in hand. What you pay for the dirt and how much gross building square footage you squeeze out of it affect the overall financial performance of the facility. But it goes beyond how much you pay for the site because you always need to consider what you will be able to build and what it is going to take to get there.

The first hurdle in maximizing your coverage is determining the setbacks and required buffers for your site. Examining the plat and verifying additional requirements with the city easily determine these. It doesn't stop there, however. More often the fire marshall and arborist are stealing valuable space and decreasing your coverage. Be sure to check what is required for fire-lane widths and turning radius with your local fire department. Also determine the required landscape areas and buffers. Sometimes these are disguised by calling them pervious cover areas or green space.

Now that you have determined the physical parameters of your site, you have to consider what improvements are in the way of maximizing your coverage. Earlier in your development process, you should have determined what existing utilities you have or, at least, how far you have to go to get them. Don't cut yourself short by not using existing utility locations to your best advantage. You will also need to satisfy the fire marshall again by installing the required number of fire hydrants and associated fire lines. Ensure you get the exact requirements as to the size of lines. Also find out if a check valve is needed and if the fire lines need to be looped or can be dead-end lines. Looping a fire line can double your cost.

Another site-improvement consideration is excavation and grading. Will the site require a lot of dirt to be moved or can you lay out the buildings to follow the natural grade? You might consider using split-level buildings to take advantage of steep grades on the site. Retaining walls can also help capture more useable space on a site with steep grades, but use them as a last result due to the significant cost of some retaining walls.

Finally, storm drainage is a significant consideration. Use surface drainage as much as possible to keep costs down and ensure your civil engineer has carefully determined the requirements for storm-water detention and filtration. Detention ponds can take up valuable space and reduce your coverage or add significant cost if you use concrete ponds or underground detention. Water-quality or filtration ponds will also become costly if not carefully placed and properly sized.

Now that you have figured out how much of the site you can use while making the fire marshall and arborist happy and spending as little as possible to shape the site, you can start laying out the buildings. This is where the site plan begins to take shape and overlaps into the unit-mix plan. This happens because you know certain width buildings will yield a certain combination of unit sizes. Don't have all your buildings the same width because a metal-building manufacturer has a clearance sale. Likewise don't get yourself in a jamb by lining all the property lines with single-loading buildings of the same width. The objective is to maximize the financial performance of your facility. Achieving the right unit mix is the key.

Unit-Mix Formulation

So how does one go about getting the right unit mix? Some have tried using the recommended unit mix of a metal-building supplier only to find out it was simply the easiest way to erect the building. Some use the same ratios of five unit sizes regardless of the geographical location or population density because it's the way another chain of stores does it. But what if you conduct a detailed analysis of the target market, carefully examine the existing competition and identify the market trends and shortfalls? I would say you were very close. First hand experience and proper reporting during lease-up is the critical factor in making unit-mix formulation a science rather than an art.

Earlier in your development process, you most likely had a feasibility study done for your target market. A good study should tell you everything about your competitors and the people living in your market. Competitor information needs to include the number of competitors, facility sizes, numbers and types of units, percentages of climate control vs. regular storage, occupancy levels, unit prices, overall appearance/condition of the facilities and comments about the managers and employees of each store. Demographic information should include population makeup, income levels, renter-occupied housing, level of commercial and industrial activity, traffic counts, major employers and traffic generators.

Now all of this information must be analyzed and compared to historical data from the same or similar markets. Where you get this critical historical data makes all the difference. This is where you need a good property-management company that has taken the necessary steps to track its stores and customers. Information collected about customers, including the type of unit leased and why they chose your facility, is used to establish a baseline unit mix for a particular market. This baseline is then adjusted to account for the demographic variables in your target market.

For example, if your target market has a higher percentage of renter-occupied housing, your average unit size will be adjusted down. Your overall demand does not change, but renters historically lease smaller units. Thus, after comparing each category in your baseline unit mix and making the necessary adjustments according to the variables for your target market, you will have a unit mix tailored for your site.

Putting It All Together

Now that you have the right unit mix for your site, you can fine-tune the site plan. As you manipulate the layout and building sizes, remember a good storage facility is one that facilitates storage. Keep your customers in mind when laying out streets and placing units. Place your largest units where they can be accessed from the fire lanes, which are typically the widest streets on the site. Likewise place larger interior units near the entry doors to the building or closest to the elevators in multilevel buildings.

Use building setbacks for paving or increasing the vehicle stacking room in front of the entry gate. Place your required parking stalls where your customers have easy access to the office. Locate the trash receptacle within site of the office or a video camera. Use concrete-filled pipe bollards at the corners of your buildings to help customers keep a safe distance from the building while turning. Don't forget safety and convenience amenities such as water fountains, vending machines, intercoms and signage.

Proper site planning and unit-mix formulation will enable you to have the most economical facility that will best compete in today's self-storage market. What it means for you is the best possible bottom line and return on your investment.

Victor Lopez is the president of National Development Services Inc., a full-service design and construction company. NDS has completed nearly 200 projects totaling more than 7.6 million square feet of storage and has won numerous awards for design and facility of the year. For more information, visit www.ndsinc.com.

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