When should I cut the roof on a van build?

What it depends on

• The layout. The fan placement depends on what's under it. Over the galley it clears cooking steam. Near the bed it moves air where you sleep. Decide the floor plan, then the roof.
• Roof structure. Van roofs have bows or ribs running across them. Openings go between them, not through them. Find them from inside before you mark anything.
• Solar and rack. Rack feet, panel sizes and the fan all share the roof. A panel that shades the fan or covers a vent costs you. Lay out the whole roof at once.
• Wiring paths. The fan needs a 12 V feed, and the solar needs a cable entry. Both paths get planned before insulation.
• Weather. Sealants have temperature and cure-time ranges in their data sheets. A cold day can mean waiting.
• Tools and nerve. A clean cut wants a jigsaw with a metal blade, a drill, a file and time. Measure many times for this one.

Worked sample: a typical sequence

1. Strip and clean. Factory panels and floor out if you're replacing them.
2. Tape the layout on the floor. Bed, galley, fridge, seating, at full size.
3. Mark the fan location between two roof bows, over the spot you chose from the floor plan.
4. Lay out the roof. Rack feet, panels and fan drawn together so nothing overlaps or shades the fan.
5. Cut. Many roof fans use about a 14 in × 14 in opening. Check the fan's install manual for the exact size and for any adapter or frame it needs on a curved roof.
6. Treat the edges. Deburr, then prime bare metal edges against rust.
7. Seal per the fan and sealant instructions.
8. Water test. Hose it down and look from inside before anything covers it.
9. Then wiring runs, insulation and ceiling.

Steps 2 through 4 are where most of the time should go. The cut itself is short.

Signs you're not ready to cut

• The bed or galley location could still change.
• You haven't decided on solar or a rack.
• You don't know where the roof bows are.
• You don't have the fan in hand to check its opening and adapter.

When to bring in a professional

A fan opening between roof bows is a common DIY cut. Get a fabricator or upfitter if the opening would cut or notch a roof bow, if you're adding a large skylight or several openings, or if you're unsure about sealing. Check the van maker's body-builder guidance on where openings are allowed for your van.