In my previous article, Campervan DIY Build Sequence: The Steps to Success, I said irreversible cuts came third in the build order: after locking in the layout and installing the roof rack, but before anything covered the metal. I summarized the step this way: Cutting an irreversible hole in a van is scary, but not technically difficult. Measure 10 times. Cut once.
I was feeling confident in my own dribble while my 2022 Ford Transit still had all its sheet metal. Once I got to the point of actually putting a saw to the second-most-expensive thing I owned, I started to feel a little different about the matter. The first cut is when a perfectly good cargo van becomes a DIY campervan, whether you finish the project or not, and if you don’t finish it, you have absolutely tanked its value.
A lot can go wrong at this step, too. A 100% properly cut hole can still be slightly in the wrong place; it could hit a structural rib, or leave something crooked. Bare unpainted steel will rust way faster than you might think, and a poor seal can leak for months or years, hidden behind finished walls and causing corrosion and rot. None of this is going to be covered by your insurance, either. You’re truly on your own.
I had no interest in proving how brave I was with a power tool, so I opted to lessen the margin of error and hire professionals. Overland Mobile Installs cut the two windows, roof fan, and air-conditioner openings, and handled most of those installations while I watched and learned.
Plan Each Cut. Really.
Cutting is the final step of this phase of the build, not the first. Before even touching the van, I needed to decide where to place the bed, onboard power system, windows, fan, air conditioner, solar array, and any other roof-mounted accessories I might want later.
I also had to think of wiring and where a future heater might go. Each opening required multiple decisions at once, all of which depended on the others. I approached the process with a surgeon’s mindset. There is no rewind button, and in this case, the skin wouldn’t heal, or at least not without a lot of expensive metalwork and paint.
This is why I installed the Flatline Van Co. Low Pro roof rack first. Inside the Transit, structural ribs run across the roof, dividing its thin skin into sections. Van builders call each section between two ribs a roof bay. With the rack assembled, I could see which bays its crossbars, fan, AC, and solar panels would take up. Roof space disappears quickly once you represent every component at full size.
The Velit 2000R Mini 48V AC went in the rearmost bay above the bed, and I wanted the MaxxFan Deluxe above the cooking area. I planned the driver’s side rear wall for the EcoFlow Power Kit, which determined the shore-power and solar cable entry points, while my two windows were specific to the forward locations. I left heater openings for later because I had not chosen the model or its final location. Grouping planned cuts is smart; cutting a speculative hole is not.
The Four Cuts I Hired Out
I hired Overland Mobile Installs (OMI) because a small error in these four cuts could damage an expensive component or a large piece of the van. The crew arrived on time and were friendly, patient, and completely comfortable with me watching. They answered every question and explained what they were doing, rather than treating the work as a trade secret. All of this reinforced my decision to use professionals.
The Windows
The sliding door received a fixed VWD window, and the forward driver-side panel received a VWD half-slider. Both are bonded with automotive urethane.
For these windows, the Transit’s factory-stamped interior panel openings define the cut lines; the challenge is controlling the large metal cutout so it does not vibrate, bind the jigsaw, or fall against anything it could maim. I wanted someone who had already made hundreds of these cuts in vans like mine.
The Fan and Air Conditioner
The MaxxFan Deluxe and Velit 2000R Mini both use an industry-standard 14-by-14-inch roof opening.
The rooftop openings worried me more than the windows. They sit directly in rain and highway-speed water on a curved, corrugated surface that flexes. The openings must clear the ribs, the components must sit flat, and their seals must remain compressed while the roof moves.
I learned that lesson on a previous van. Its rooftop AC developed a leak that kept appearing and disappearing. Eventually, I realized the roof was “oil-canning,” or flexing between two shapes. The seal would leak, I would hit a bump, and the roof would pop back into place, stopping the leak. It took me a long time to understand what was happening.
That experience is why the DIYvan internal support framing for the MaxxFan and the Velit air conditioner matters. I added both after OMI’s installations. Each contour-matched frame bonds to the inside of the roof with Sikaflex 221 adhesive. The fan and AC installation hardware pull against it, spreading the load and strengthening the roof panel. Without it, the hardware can distort the roof, and road movement can unload the gasket.
The fan and AC unit seal differently. The MaxxFan uses butyl rubber tape beneath a screwed-down flange and lap sealant over it all. The Velit clamps down onto a thick gasket and has no rooftop screw heads. Follow the system that each component was designed to use. More sealant won’t fix poor support.
I watched OMI use these six steps for every opening: measure and mark the opening carefully, cut slowly, deburr, apply primer to raw steel, seal, and test. They checked interior and exterior clearances repeatedly and always controlled the sheet metal before freeing it.
Remarkably, they never looked like they were rushing to finish despite the brutal Texas summer heat, and they never got frustrated when the metal or blade misbehaved. I was paying for the cumulative experience, judgment, and deliberate execution, not the actual time on the job or technical savvy. Actually, never mind, I paid for that too.
The Beginner-Status Cuts I Made Myself
My four cuts fell on the safer side of things and required only hole saws. On the roof, a Scanstrut DS-HD6 will carry the permanent solar cables, and a larger DS-HD10 will preserve a path for accessories such as a cell booster or Starlink Mini. On the driver side, a Marinco 30A inlet would handle shore power, while a Scanstrut Ventura SC-V-S3 XT60 connection would connect portable solar into the EcoFlow Power Kit.
The DS-HD6 and DS-HD10 compress proper seals around the cables rather than relying solely on a blob of sealant. I chose Scanstrut and Marinco because every professional builder I asked recommended them. Water and electrical systems are a bad place to save a few dollars with anonymous fittings.
One big benefit of using a hole saw is that it limits geometry errors: the pilot bit pins the center, and the blade sets the diameter. The fitting’s flange then covers the edge, and there is built-in leeway for the final positioning. That is much more forgiving than following a large stamped window opening with a jigsaw or fitting a rooftop component between ribs and rack crossbars.
A hole saw’s forgiving nature doesn’t mean I wasn’t also super-careful. I still checked the clearances from both sides, carefully planned cable routes, and made sure I could access mounting hardware. I also ran the bi-metal hole saw slower than I have ever run any power tool, and actually used the bubble level in the drill to keep it square. I collected the metal chips, deburred the opening, applied primer, and installed the fitting with its intended gasket, compression hardware, and sealant.
Repeat: Measure 10 times, cut once. A perfectly round hole that opens into a rib is still a bad hole. I know; I’ve done it.
Test and Then Test Again
It’s so important to water-test everything before adding anything that could hide a leak. Luckily, it rained a few times right after the installs, giving me real-world testing opportunities. If I had not, I would have used a hose and given the water ample time to work.
I used a flashlight and dry towels to scrutinize every sealed opening. A leak is annoying now; after insulation and panels hide its path, the same repair becomes demolition, takes much longer, and costs a lot more to fix. I will keep checking that things are watertight after heat cycles, rain, and highway miles because sheet metal and sealants move.
Would I Cut Them Myself Now?
Now, knowing what I do and having seen professionals do it, I would cut all eight openings myself. I would still be scared of screwing up, and I’d measure everything an unreasonable number of times, but now I understand the process rather than solely relying on the instructions.
The two VWD windows I used made the cuts less mysterious than they look from the outside. They follow large factory-stamped inner panel openings, so the van provides an obvious template, and the bonded glass overlaps the cut. It is still possible to screw up, but the basic line is hard to miss.
The roof is definitely riskier, but I now have a solid plan: carefully plan around the roof rack and internal ribs, use contour-matched internal supports, protect the raw steel, follow each component’s prescribed sealing method, and test everything.
If anything gave me the slightest pause, I would absolutely call OMI. Better safe than sorry. I may do that if I end up using a gasoline heater. This type of heater requires tapping the vehicle’s main fuel tank, which could be sketchy, and then routing the heater’s intake, exhaust, and electrical to a device whose sole job is to make a fire under the van. This is not the time for hubris, clearly.
By the end of this part of the process, I was ready to tackle roof cuts myself. I still winced and gritted my teeth when I witnessed the jigsaw blade plunge through my roof the first time.
It helps that by this time, the van wasn’t a pristine, fully intact vehicle that I was about to violate. It felt like a project, and I understood the decisions I’d made that led me to this point. I am not suddenly fearless, but I’m not guessing anymore. That is enough confidence to make the next cut.
