Self Storage Construction

Planning and Numbering Your Storage Units

by Joe and Lolita Bader


My wife and I own a self-storage facility and we have also been a door number vendor to the storage industry since 1985.  Because we are involved in both sides of the business, we have a unique perspective on unit numbering. The purpose of this article is to help you better plan your numbering system on future projects and, if you are having problems with your current numbering plan, give you ideas to help correct common mistakes.


The essence of a number plan is to see the project from the tenant’s perspective.  Your unit numbers should make it easy for a tenant to find his or her unit.  It should be simple for a manager to direct a tenant to any unit on your property.  From your front gate and from your office door, the numbering plan should be logical to anyone looking at it for the first time.

The most common planning mistake that we see is owners blindly relying on an architects or engineers site plan for unit numbering.  Architects and engineers are experts at structure and space but they may not see your project from the tenant’s perspective.  They also may not know of your future expansion plans.

One of the problems we had in 1981 when we built our first phase was we did not plan for a phase two building extension.  We numbered one side of a building and continued the number sequence on the other side.  In our second phase, we extended that building and the numbering no longer made sense.  We had to re-number all of our units.


Most storage facilities have several buildings and many have multiple floors.  It makes sense to distinguish different buildings or floor levels with different numbering sequences.  The first building may start with 101 or A1 and the second building with 201 or B1.  This differentiation helps your tenants, especially new tenants, find their unit quicker and helps management easily know where a tenants unit is located on the property.

Smaller facilities may not need to differentiate between buildings.  For example, if they have 81 units they use 1 through 81.  If there is no room for expansion at that site, this simple sequence may be the best.

From our experience as door number vendors, about ninety percent of our clients use numeric sequences; that is 101 and not A1.  Less than ten percent use alphanumeric.  The main advantage of the alphanumeric system is that you can have up to 26 buildings, floors or isles and identify each with a single character.


An alphanumeric system can be advantageous when it is necessary to divide an existing large unit into two or more smaller units to change your unit mix.  Unit 121 is divided into 121A and 121B.  This will keep your number sequence intact and allow for changes back and forth to satisfy changing consumer demands.

The major drawback with an alphanumeric system is that tenants sometimes can’t remember the alpha character.  They know they are in unit 21, but don’t know if it’s A21 or H21.

Another potential drawback for alphanumeric unit numbers is gate software codes.  Be certain that the software you plan to use will accept your unit numbering system.  If this is a problem at your existing facility, it can be resolved by a sign near your entry pad telling tenants to use 101 instead of A1 and 201 instead of B1.

The chief advantage of a purely numeric system is in its simplicity. Tenants are more likely to remember their unit number and it makes life a little easier on managers.


Where you place the number on the unit can create problems.  Your unit number should leave no question in the tenants mind as to which unit is theirs.  For example, if there is a one-foot divider between two units and you put a unit number beside the hasp between the two units it will confuse some tenants.  The manager will be using valuable time each month helping tenants who are trying to open the wrong unit.

Some facilities have the numbers placed on the roll-up doors themselves.  When the door is up, the number is no longer visible. It’s also difficult to put a number on the corrugations and they make the number more difficult to read. If the door is on hinges and is flat and smooth, putting the number on the door might be the best solution.

It is my opinion that the best place for a unit number is centered above the door.  If the frame above the door is tall enough, that is an excellent place.  The space above the door frame is also ideal.  The area should be relatively flat, smooth and above all easily seen.


One of the trends in our industry is away from the traditional metal façade and toward other finishes like rock and stucco.  Your unit numbers are not going to be as visible or look as sharp on these rough textures.  Vinyl numbers or painted numbers don’t work well here.  It necessitates putting the numbers on a blank.  It is my opinion that painted aluminum is superior to plastic as a substrate.  It has an oven baked paint finish similar to auto paint and it does not warp or break down in the sun like plastics.  Even our plastic suppliers recommend aluminum for durability.

To attach the aluminum number plates to your building, you can drill and use screws or rivets, or you can use heavy-duty construction adhesive.  Adhesive is by far the fastest and easiest option.  Some of our customers have been using it for over ten years and say their numbers rarely come unglued.  Heavy-duty construction adhesive comes in a calking tube and is made by several manufacturers including Liquid Nails.  It is available at home improvement stores.


When we built our facility in 1981, most unit numbers were painted by sign shops.  Today, the sign artist is becoming obsolete and the computer cut vinyl lettering has taken over the market.  The best paint and the best vinyl have about the same outdoor life.  I believe vinyl numbering is a better choice because it is accurately spaced and perfectly dimensioned.

The most common complaint we hear from facilities that have to renumber their units is that they bought sheets of vinyl numbers from a home improvement store.  There are different grades of vinyl and different grades of the adhesives that make the vinyl adhere.  The sheet products we’ve seen use an intermediate grade of both vinyl and adhesive.  They will begin to peel and shrink long before the high performance vinyls.  If you have to replace your numbers, your major problem and cost will be removing the remains of the old numbers.  We’ve found two methods that work.  You can rent a hot water pressure washer that can heat the water to at least 210 degrees.  It will blast the old vinyl off but can also damage the paint on your buildings.  Another tool that works well looks and feels like a large pencil eraser disk that fits on a standard drill.  The spinning creates the heat and friction to remove the vinyl, but it is not as fast as the pressure washer.  Getting the old vinyl off will take many times as long as putting a new number on.  A more efficient solution might be to use an aluminum plate with the new number on it over the old number.

The industry leader in vinyls and adhesives is Scotch 3M.  They have been in business longer and have the most advanced research facilities.  There are other manufacturers of quality vinyls, but for the product life we need in self-storage, going with the best doesn’t cost that much more.  Scotch manufactures a range of vinyls which include intermediate grades, which are not recommended for unit numbers.  According to their technical department, the best product for our industry, with the best vinyl and best adhesive, is called Scotchcal 220.  The product life is claimed to be seven years, but we have had it on our facility in South Texas with high heat and humidity for over fourteen years and it still looks good.  Scotchcal 220 comes in 99 different colors to complement your door, trim or building color.  For good visibility, use a color for your number that has a high contrast to the background color.

Your pre-spaced vinyl unit number comes to you so that all the digits of each unit number are on one piece, ready to apply.  Simply peel off the backing, stick it on your building and peel away the masking tape that keeps it pre-spaced.  If you use a ladder to apply the numbers, it will take you less than five minutes per unit to put your numbers up.  If you can reach the place you need the numbers standing in the back of a pickup truck , you and a driver can put numbers on in less than one minute per door.  It’s fast and easy once you do the first few.

The most common size number ordered from us is two inches tall.  It is bold enough and big enough to be easily seen from a twenty-five foot driveway.  For your boat and RV spaces or if your driveways are wider, you may want a three or four inch number.  Ask for a free sample and see how it looks at your property.


In summary, visualize your completed facility from the tenant’s perspective.  Be sure your numbers are easily seen and that they clearly identify the unit so that your tenant will not be confused.  Chose a number product that will be low maintenance.  Above all, keep it simple so that the numbering plan you use makes your property tenant friendly.