Creating a Napkin Sketch Self-Storage Layout: Understanding Basic Facility Design

When building a self-storage project, you need to start with a good layout, but it can take weeks or even months before you get a preliminary sketch back from your engineer or designer. Having basic layout skills will help you create your own “napkin sketches” and contribute more to the overall process. Following are some basics to help you understand and master the essentials of site design.

Layout Basics

Let’s begin with some essentials, focusing on single-story buildings. Below are some major factors that go into a self-storage layout, including building size, driveway widths, climate control and more.

Steel is typically manufactured in 10-foot lengths, so buildings are usually designed in 10-foot increments for cost-efficiency. The most common building is a 30-foot-wide, non-climate-controlled structure, which provides options for a variety of unit sizes. If you have fewer than 30 feet available, you can build something narrower, such as a 20-foot-wide building with access on one side; but this isn’t preferable, as it costs more per square foot to develop.

You can also build wider, at 40 feet, but this size should be used with caution. These buildings are best used to provide back-to-back 10-by-20 units; they otherwise don’t divide well to provide a balanced layout. I generally won’t use a 40-foot-wide building unless I happen to have 10 feet of leftover space on my parcel. In that case, I just add that space to one of my 30-foot-wide buildings.

Driveways between buildings are typically 25 feet wide. If you’re short a foot or two, you can make them a bit narrower. In some jurisdictions, zoning or fire regulations may require wider distances between buildings.

At the end of the buildings, the driveway width is typically 30 feet or wider to provide the required minimum vehicle-turning radius. Dead ends should be avoided. Special consideration may need to be given to snow removal and stacking.

If there’s a significant grade change on site, the buildings can be stepped if their length runs perpendicular to the grade. On real steep grades, over/under two-story buildings may be the best solution (think of a walk-out basement). All other things being equal, more often than not, if a building’s long side is parallel to the longer property line, you can build more square footage.

Building With Climate Control

The more climate-control units you build, the more square footage you’ll get on the site, since climate-controlled buildings are wider than non-climate-controlled ones. If the property is small, it can even make sense in certain areas to provide all or mostly climate-controlled units to get enough square footage to make the project feasible. A good goal to aim for on your first project is 50,000 square feet of rentable square footage.

Your feasibility study will help you determine how much climate-controlled vs. non-climate-controlled space should be provided based on your location and competition. For layouts created before the study is complete, you could simply use 40 percent climate control and 60 percent non-climate control, or two to three non-climate-control buildings for every climate-control building.

Climate-control buildings come in many widths. Typically, the smallest is 45 feet wide, with exterior, non-climate-control units on one side and no exterior units on the other. A second common size is 65 feet wide with interior, climate-control units serviced by a single hallway and exterior, non-climate-control units accessed from the driveway on each side of the building. Due to the higher cost of mixing climate-control with non-climate-control space, in many areas, it’s more efficient to make the entire building climate-control, with no exterior units.

Climate-control buildings can be much wider, but there are a host of factors that need to be considered that will require the input of a professional self-storage designer. For example, you need to think about fire sprinklers.

If you don’t have adequate city water to provide fire-sprinkler protection, the width of the buildings might be limited by the cost to provide fire walls, which are typically required for every 5,000 square feet of building space. In this case, it’s more cost-efficient to build smaller than 5,000 square feet. For example, a 30-foot-wide, 160-foot-long building may not require a firewall, as it contains only 4,900 square feet. If that same building were 170 feet long, it would require a firewall.

Gathering Information

The more information you obtain about your property, the more accurate your layout sketch will be. Of course you want to walk the site to observe any driveway obstructions, topography, wetlands or other restrictions. A visit to the city planning department is also very useful. You should be able to gather many of the following details from the seller or the city files:

• Boundary survey
• Topography, wetland or flood-plane surveys
• City mapping of the property
• Sales map with dimensions
• Deed

You’ll also want the following information from the planning and zoning department. Some of these items can be found online:

• Building setbacks for front, side and rear yards
• Maximum building coverage
• Buffer requirements
• Is storm-water detention required?
• Is pavement permitted in the building setbacks?
• Is there city sewer and city water, or is a well and septic system required?

Sketch Preliminaries

It’s best to keep your first sketch simple. For buildings, I suggest the following:

• 30-foot-wide, non-climate-control buildings with 25-foot driveways on both sides and 30 feet at the ends
• 60-foot-wide, climate-control buildings with 25-foot driveways on both sides and 30-foot driveways at the ends of the buildings
• 45-foot-wide, climate-control buildings with 25-foot access on one side and no access on the other (exterior, non-climate-control units on the access side)

Start with a climate-control building on one side, with a driveway on the interior. Consider a building ratio of one climate-control building to every two or three non-climate-control buildings. To start, assume there will be no driveway in the side yards due to zoning, grading, landscaping or an area needed for snow management. Leave an area of about 150 by 150 feet (half an acre) on the low side of the site for storm-water drainage detention.

Don’t assume you can fill in wetlands. In fact, I would recommend that if there’s wetland on the property, the building and paving should be at least 50 feet away.

For your initial sketch, it may not be clear if the buildings should be parallel or perpendicular to the existing road. Start with buildings perpendicular to the street; you’ll be right more than half the time. Now let’s get down to the sketch.

Creating Your Napkin Sketch

If you own a scale and know how to use it, you can make your sketch to scale, but it’s not a requirement. You can still make a sketch based on the dimensions you know. For example, let’s assume you have a 4.8-acre lot that’s 250 feet wide (street frontage) and 829 feet deep. It slopes away from the street toward the rear of the property, with a 75-foot front yard, 25-foot side yards and a 50-foot rear yard.

Now, let’s use a design guideline of 5 acres equals 5,000 square feet of building potential. In this case, because the property doesn’t include wetlands or steep slopes, and doesn’t have an odd shape or very restrictive zoning, we can probably beat that estimate.

First, take your property width (250 feet) and subtract the two side yards (50 feet total) to see how much space you have for buildings and driveways. In this case, that’s 200 feet. Next, subtract 45 feet for one climate-control building and 25 feet for one driveway. Then subtract 30 feet for a non-climate-control building and another 25 feet for a driveway. Continue subtracting 30-foot buildings and 25-foot driveways until you run out of space.

Once you have your “leftover” space, you can determine if you should adjust the layout. The goal is to maximize square footage and minimize leftover space. In this case, there’s 20 feet left over, which can be split and added to the side yards. A better solution would be to increase the width of the climate-control building from 45 to 60 feet. That increases the square footage and leaves just five feet left over.

Now that you’ve determined the widths of the buildings, you need to determine their length. For this project, let’s assume you’re going to build in two phases, with three buildings in each phase. Take your property depth (829 feet) and subtract 75 feet for your front yard and 150 feet for the storm-water detention pond. Finally, you need to subtract 30 feet for two driveways, and 30 feet for between the buildings.

That leaves 514 feet, which means you can build two buildings at 257 feet in length, or round them down to 250 feet with 14 feet left over. If you can use less space for the detention pond, you could possibly go to 260 feet in length. The more you practice, the more you’ll realize there are several options to reduce the leftover space and increase your total square footage.

Let’s say each phase is going to include one 60-by-250 climate-control building and two 30-by-250 non-climate-control buildings, for a total of 30,000 square feet. The entire project will be 60,000 square feet. Any steep slopes, wetlands or other restrictions will reduce that square footage. Here’s the sketch:

Looking at this, it appears both climate-control buildings can be longer since no driveway is required at the ends. It also appears the area for the storm-water retention basin may be too large; a review of the slopes and water table may be required to determine the final area. A more detailed look at the entrance and parking is also necessary.

The Final and Best Plan

In the end, the layout comes together after detailed boundary and topography plans are complete. More often than not, the total square footage of the project will decreases as property details are added. These might include wetlands, utilities, existing roads and other features.

Your engineer will develop the final design based on these items as well as zoning and building regulations and your feasibility report. A good civil engineer will even take into consideration political influences to increase your odds of approval. If he doesn’t have significant experience in self-storage, an industry architect or designer will be required.

Keep in mind, your napkin sketch is just an outline. By understanding the basics of site design for a new self-storage facility, you’ll be able to better assist in the overall development of your next project.

Marc Goodin is president of Storage Authority Franchising and the owner of three self-storage facilities that he personally designed, built and manages. He’s been helping others in the industry for more than 25 years. To reach him, call 860.830.6764 or e-mail [email protected]. You can also purchase his books on facility development and marketing in the Inside Self-Storage Store.