Nearly every food trailer on the road depends on a kitchen it does not own. The health department calls it a commissary or a servicing area, and it is where you fill your water, dump your grey water tank, wash your equipment and store your stock. You sign an agreement with somebody who has a licensed kitchen and you pay them for it every month.
That is the part nobody budgets for properly. In Boulder County a commissary agreement runs around $800 a month, and it climbs toward $1,500 depending on how much of the service you actually take. Call it ten to eighteen thousand dollars a year, every year, for a kitchen you do not own and cannot change. On top of the money you are driving there whether you feel like it or not, and if the operator closes or sells up, your licence has a hole in it until you find another one.
This 16ft trailer was built so its owners would not be in that position. It is a service trailer and it is also, by design, a commissary, and Boulder County Public Health approved it as one. That single decision changed almost everything about how we built it.
It went to a pair of owners in Boulder, Colorado, running a fancy toast and iced coffee menu. At their request we are not naming the business here.
What it takes to make a trailer function as a commissary
A normal 16ft trailer ships with a three compartment sink and a hand wash sink, thirty gallons of fresh water and forty of grey. That is enough to trade for a day and go home.
This one carries a prep sink, a three compartment sink, a hand wash sink with splash guards, and a mop sink. The mop sink is the part people skip and the part that matters. Boulder County’s own commissary agreement lists what an approved commissary has to provide, and a mop sink is on that list alongside a hand sink, a prep sink, a three bay sink, refrigeration and dry storage. You cannot claim to be a servicing area if there is nowhere to empty a bucket.
Water went up with it. The trailer holds 75 gallons of fresh and 90 gallons of grey, both insulated. Colorado’s retail food rules require the waste tank on a mobile unit to be at least 15 percent larger than the fresh tank. Ninety over seventy five is twenty percent, so there is margin rather than a number that only just passes. The insulation is not a luxury in a town at 5,300 feet where the shoulder seasons bite.
There is also a second drain in the floor, which is the detail that gives the whole thing away. A trailer you wash down at the end of a shift needs somewhere for that water to go.
It worked. Boulder County Public Health approved this trailer to operate as its own commissary. That is worth saying carefully, because approval is granted to a specific unit with a specific equipment list in a specific county, and it is a determination your health department makes rather than one a builder can promise you in advance. What we can do is build the unit so that every physical requirement on the list is already there and the conversation is about paperwork rather than plumbing. Boulder County Public Health is on 303-441-1564 and that call should happen before the build, not after.
A conveyor oven is not a griddle, and it changes the permit
The cook line here is built around a conveyor oven. No fryer, no flat top as the main engine of the menu. That is unusual in our shop and it is worth explaining, because it affects the hood, the fire system, the labour and the licensing all at once.
A conveyor oven is consistent in a way a griddle never is. You set the belt speed and the temperature and every piece comes out the same, whether it is the first order of the morning or the two hundredth on a Saturday. It does not need a skilled cook standing over it. For a two person operation that is the difference between being able to hire and not being able to hire.
The bigger consequence is that a conveyor oven toasting bread is not producing grease laden vapours. Fire code hangs the heavy requirements on that phrase. Under the International Fire Code, the mandatory kitchen exhaust hood and the automatic fire extinguishing system apply to cooking equipment that produces grease laden vapours. Take the grease out and the oven sits under a Type II hood, which moves heat, steam and odour rather than grease, and it does not need suppression over it.
That is a real saving and a real simplification, and it is also the single easiest thing to get wrong. The rule follows the equipment, not the concept. Put one fryer in the corner for hash browns next season and the whole conversation changes.
Which is exactly why we did not build this one to the minimum. The code would have allowed a Type II hood with nothing over the oven. We fitted a Type I hood with fire suppression mounted directly above the equipment instead, deliberately, to future proof it. Menus change. Owners add a fryer, or sell the trailer to somebody whose menu is nothing like theirs. Retrofitting a Type I hood and a suppression system into a finished trailer means pulling the ceiling apart, and it costs several times what fitting it during the build does. Paying for it once at the start buys the owners the right to change their minds later.
Two things to do before you assume you can copy this. Get the classification in writing from your fire authority rather than relying on a builder’s opinion, including ours. And check which code edition applies where you park, because the City of Boulder adopted the 2024 International Fire Code effective 1 August 2025, and there is older Boulder guidance still circulating that references the 2018 edition.
The sandwich prep in the middle of the hood
The owners asked for the refrigerated sandwich prep to sit in the middle of the hood run rather than off to one side, which is not how we normally lay a line out. We build the cold side away from the heat, because a prep table sitting under a hood works harder to hold temperature and its compressor lives a shorter life.
They had a reason. Their build is assembled to order at the window, and putting the toppings between the oven and the pass means one person can load, top and hand out without turning around. On a menu where the oven does the cooking and the human does the assembly, steps saved at the pass are worth more than compressor life.
We built it their way and said plainly what the trade was. That is usually the right answer. The operator knows their service better than we do, and our job is to make sure they are choosing the trade rather than discovering it in August.
Around it sits the cold and dry storage a commissary needs rather than what a service trailer needs: a chest freezer, two refrigerators, a prep table, a service table and a work table, plus space and power set aside for a coffee machine so the iced coffee side is not fighting the food side for an outlet.
Built like a building, not a box
Because this trailer has to pass inspection as a food facility rather than just as a vending unit, the shell was built to a higher standard than a normal trailer needs.
Behind the stainless walls there is 9/16 inch plywood and an inch and a half of insulation. The floor is aluminium diamond plate. Where the floor meets the wall there is rubber coving, which is the curved strip that stops the ninety degree corner existing at all. A square corner is where grease and water collect and where an inspector puts their torch. Coving turns that corner into something you can mop through.
There is trim between every wall panel for the same reason we fit it on every build: a seam collects grease you cannot see or reach, and a trailer that smells is a trailer nobody wants to work in by year two.
Lighting is shadow free LED, which matters more in a trailer than people expect. A single strip down the centre throws your own body shadow onto whatever you are working on. Air conditioning has heat, because Boulder shoulder seasons swing thirty degrees in a day.
Two doors, and why that is not a luxury
The back has a ram door, which is the full width fold down ramp, and beside it a separate man door. RV steps on both.
On a normal trailer you get one or the other and you live with it. On a unit doing commissary work you are moving stock in and out constantly, and a ramp you have to drop and lift every time somebody carries a tray is a genuinely miserable way to spend a season. The man door means the ramp stays up except when something big is going in.
The better reason is the one fire inspectors care about. Two doors give you an ingress and an egress. If something goes wrong at one end of the trailer, the people inside can get out the other way instead of being trapped behind the thing that is on fire. Inspectors look for that, and on a unit this size with a cook line running down one wall, they are right to.
The service window is a self closing unit with an outside shelf, which is standard on our builds and is worth having: a window that closes itself is one less thing to fail an inspection over on a windy day.
Power and gas
The generator lives in an insulated, lockable box that slides out for service. Three things are happening there. Insulated, because a generator four feet from a service window is the loudest object in the customer’s experience. Lockable, because generators are the single most stolen item off a parked trailer and an unlocked one is gone on the first quiet night. And it slides out, because a generator you cannot reach is a generator that does not get its oil changed, and that is how a two thousand dollar unit dies in eighteen months.
There is also a shore power connection, so on sites with a pedestal the generator stays off entirely.
Propane sits in ventilated cages with the gas lines run under the floor rather than through the cabin. Ventilated is not decorative. A sealed compartment holding a leaking cylinder is the failure mode the fire code exists to prevent, and an inspector will look at the vents before anything else.
The generator box also doubles as a prep table on the outside, which was not clever design so much as noticing that a flat lockable steel box at counter height is a flat surface somebody is going to use anyway.
Licensing a trailer like this in Boulder
Boulder is stricter than most Front Range towns, and unlike some of its neighbours it runs a real city level licence rather than leaving everything to the county. Budget for three separate agencies.
Boulder County Public Health
The retail food licence comes from Boulder County Public Health, on 303-441-1564. Plan review comes first: a $155 application fee at submission, then hourly review charges capped at $900 in total. They want the floor plan, the equipment list, the plumbing and warewash layout, the water heater specification and your commissary agreement.
On the licence itself, Boulder County publishes a mobile unit full service fee of $481 for 2026, rising to $567 in 2027 and $682 in 2028, with prepackaged units at $338, $394 and $475. Those figures match the statutory schedule Colorado adopted under Senate Bill 25-285, which is why they step up year on year. Contact the plan review specialist at least five business days before you want to open so the opening inspection can be scheduled, and expect to pay the annual fee at that inspection.
Licences run the calendar year, so the same trap applies here as everywhere in Colorado. Buy one in October and you are buying another in January.
City of Boulder
Boulder is home rule and it does require its own licences, which surprises people coming from Lakewood or Longmont.
First, a sales and use tax or business licence, which is $25 under the city’s fee schedule, with another $25 if you let it lapse and have to renew late. The combined sales tax rate you charge in the City of Boulder is 9.195 percent as of 1 January 2026, made up of the city’s 3.86 percent, the state’s 2.9 percent, the county’s 1.335 percent and RTD’s 1.1 percent. That is one of the higher rates on the Front Range and it belongs in your pricing rather than in your surprise.
Second, and this is the one people miss, Boulder has a Mobile Food Vehicle licence. It costs $100 to apply plus $216 for each twelve month period, and the licence runs a two year term expiring on 1 March of the second year. To apply you need the county retail food licence, the city business licence, vehicle registration and insurance, driver’s licences for everyone who will tow or drive it, a certificate of insurance naming the city for a million dollars of liability, and fire inspection approval.
The operating rules are where Boulder gets specific, and they will shape your whole route:
- Four hours maximum at any one location
- 150 feet from any residential zoning district
- 150 feet from any existing restaurant, unless waived in the BC-1 zone
- 200 feet between mobile food vehicles in the public right of way
- No more than four mobile food vehicles in the Mixed Use, Business, Downtown or Industrial zoning districts
- Parks and the airport are possible with the right approvals
Read the 150 foot restaurant rule twice. In a town with as many restaurants per block as Boulder, that single line removes most of the addresses a newcomer would think of first, which is exactly why brewery lots, private commercial property and event bookings do the heavy lifting here.
Boulder Fire-Rescue
Fire inspection approval is a required document for the city licence, so this is not optional and it is not last. The City of Boulder adopted the 2024 International Fire Code, effective 1 August 2025, and it did not locally amend the section covering mobile food preparation vehicles, so the model code applies as written.
We could not find a published dollar figure for the mobile food vehicle fire inspection itself, so do not budget from any number you read online, including this page. Call Boulder Fire-Rescue and ask. While you are on the phone, get them to confirm the hood classification for your equipment in writing, because that is the answer that decides whether your build needs a Type I hood and suppression or a Type II hood.
A note on CU and open space
Two things worth knowing before you build a plan around them. Third party trucks are not permitted on CU Boulder’s main campus, and where they are allowed on east and south campus it is by invitation from a university department rather than by application. And Boulder County Open Space prohibits commercial activity on its parks and trails, so those trailheads are not a venue no matter how many people are standing at them on a Saturday morning.
Walkthrough video
What a build like this costs
Custom food trucks start at $55,000 and custom food trailers start at $40,000. A typical 16ft truck comes in around $72,000 and a 22ft around $110,000. A commissary specification trailer sits above a standard 16ft trailer, because the extra sinks, the larger insulated tanks, the second drain, the heavier wall build and the two doors all cost real money.
Whether that is worth it is arithmetic you can do on the back of an envelope. A Boulder County commissary agreement at $800 a month is $9,600 a year, and at $1,500 it is $18,000. Set that against what the commissary specification adds to the build. For most operators the upgrade pays for itself inside two or three years and then keeps paying, and it removes a dependency that was never really under their control. For an operator who already has kitchen access through a family business or a second site, it does not, and we will tell you so.
Build time is about six weeks from order. Plan review runs alongside that and is the part most likely to add time, so start it early.
Frequently asked questions
Can a food trailer be its own commissary?
Yes, in the right circumstances. Boulder County Public Health approved this trailer to work as its own commissary. That approval attaches to a specific unit and equipment list in a specific county, so it is still a determination your own health department makes rather than something a builder can promise. What a builder can do is include every physical thing an approved commissary has to have, which in Boulder County means a hand sink, a prep sink, a three compartment sink, a mop sink, refrigeration, dry storage, and the water and waste capacity to support them. Ask Boulder County Public Health on 303-441-1564 before you commission the build, not after.
Does a conveyor oven need a fire suppression system?
The fire code hangs its hood and suppression requirements on equipment that produces grease laden vapours. A conveyor oven toasting bread generally does not, so the code will usually allow it to sit under a Type II hood with nothing over it. That is a classification your fire authority confirms for your specific equipment list. We fitted this trailer with a Type I hood and suppression anyway, because a menu that grows a fryer later is far cheaper to allow for now than to retrofit into a finished build.
How big do the water tanks need to be?
Colorado requires the waste tank on a mobile unit to be at least 15 percent larger than the fresh water tank, sloped to a drain of at least an inch with a shut off valve. There is no single statewide minimum gallon figure; the size you need comes out of your equipment and your service, which is what plan review is for. This trailer runs 75 gallons fresh and 90 grey, which is twenty percent larger and gives margin rather than a bare pass.
What licences do I need to run a food trailer in Boulder?
Three. A retail food establishment licence from Boulder County Public Health, a City of Boulder sales and use tax or business licence at $25, and a City of Boulder Mobile Food Vehicle licence at $100 to apply plus $216 per twelve month period. Fire inspection approval from Boulder Fire-Rescue is a required document for the third one.
How long can I stay in one spot in Boulder?
Four hours at any given location. You also have to stay 150 feet from any residential zoning district and 150 feet from any existing restaurant unless it is waived in the BC-1 zone, and vehicles in the public right of way have to be 200 feet apart.
Trailer or truck for a build like this?
A trailer, for this menu. Commissary functions want floor space and tank volume more than they want a drivetrain, and a trailer gives you both for less money. The cost is that you need a tow vehicle and somewhere to park two things instead of one.
More reading
- How to find a commissary kitchen near you
- Food truck inspection requirements in Boulder, CO
- Food truck or food trailer in Colorado
- Colorado food truck permits in 2026
- What a food truck actually costs to run each month
Recent Colorado builds
- 14ft roasted corn food truck built for Lakewood, Colorado
- 16ft catering food truck built for Golden, Colorado
- 14ft Korean food truck built for Castle Rock, Colorado
If you are weighing up whether to build commissary capability into your own unit or keep renting kitchen time, call or text and we will go through the numbers and the plan review before anything gets drawn. We have built around 500 food trucks, trailers, bus conversions and van conversions, and we ship anywhere in the country.
Jacob Varghese
Zion Foodtrucks
719-722-2537