Help making raised roof for a mini van

[nopeda]

Hi,

I bought a Honda Odyssey because it has the most cargo space for a vehicle of that sort and am making a raised roof camper out of it. It's a very time consuming and difficult process for a person in my unskilled position because the roof is not flat like in larger vehicles but curved front to back and side to side so there are no nice straight cuts to make the footing? or whatever it would be called in this situation. Once that's accomplished everything else should be a whole lot easier but getting there is very slow and difficult so I'm hoping there are some techniques people can share for figuring out how to mark and cut these angles. I've bought a thin blade 9" bandsaw which makes things possible I couldn't do with a basic table saw or chop saw or even a sawzall imo. Can anyone suggest good ways to deal with the angles? I've been using cardboard and cutting it out then putting it in place on the roof to make sure it fits then trying to transfer that to the wood and mark it having some success with that method but it slopes front to back and also side to side so I'm hoping there might be videos or some other sources to explain how to deal with multi-angle cuts like this. Not just multi-angle also curved but I've been dealing with that by only using lengths of about 8" or less. 

Another thing in question is about wood glues and wood fillers etc to use. There is a trough in the roof of the vehicle meant for a roof rack that I'd like to fill in with something, probably not something that would adhere to the wood but that could be used to fill the trough then later be drilled to put bolts through to inside the roof for attaching lock nuts for holding the frame. The trough filler in that case would be to prevent water from puddling up if it gets in there and also hopefully to provide some stabilization for the bolts that go through it.

In building up the columns where the bolts will go through to hold the frame so far they are turning out to be like shims and maybe that's what at least some of them will have to be. What should be used to bond all those pieces together after they are cut to shape and size? I'm thinking wood glue and screwing them together, then fill the gaps with a strong but somewhat flexible wood filler of some sort. A structural? type of wood filler? In my limited experience I've used some wood filler that turned out very dry and crumbly. Though it was hard that doesn't seem like a good type for this application and should be avoided but how to avoid getting something similar?

After the frame is built the plan is to close it in with plywood again having the problem of transferring the shape of the curved roof to the plywood for cutting. Then probably use a quarter round molding maybe plastic? around the bottom using a wood filler adhesive or something?? as the main way of keeping water out. Caulk? or wood fill or?? all joints. Then fiberglass with cloth and resin the entire structure. 

Thank you for any advice and suggestions on how to go about doing this project!

David in Maine, USA
 

[Don Z.]

Easiest would be to scribe it.  Rest a "straight" board across the top (you'll need to do this four times, once for the front, once for the back, and again for each side.  "Level" the board so you know the top side will be level/parallel.  Then use a compass or a set of dividers at a set distance.  It doesn't matter what, just keep it constant.  For this, let's say it's two inches.  Then "trace" perpendicular to the roof... you'll be measuring that two inches along the way, and you should be tracing an arc that matches the roof curve.  Then, transfer that arc (back trace) to the board you're going to cut.  Cut along the line and you should have a matching fit.  This is similar to spilling a plank for a boat, and there are lots of videos on YouTube outlining that.  Once you get the hang of it, it should be pretty easy.

[Tpt life]

Watch some boat building videos. Often they start with more or less straight joinery, then use long batons to sculpt framing member to “fair” curves. 

[wtnhighlander]

Assuming that you aren't trying to use exposed wood grain as a design element, I suggest automotive body filler to magage small gaps and smooth transitions. It adhered to wood as well as metal, but should not be relied upon as 'structure'. It needs a solid base underneath.

For the roof channel, epoxy putties, like JB Weld or Milliput, are easy to form into the space, can be sanded & painted, and will even take light-duty threaded holes for bolts. If a stronger connection is needed, I would embed a nut into tge epoxy, rather than thread it directly.

Here is an example of wood used to construct a car body, but you will probably get more technique from a boat building video, as @Tpt life suggested.

 

[Don Z.]

As I'm thinking about it a little more, I'd probably take a short cut:

Build a "box" with all four sides, and balance it on the roof.  

Get a bunch of popsicle sticks and a hot glue gun.  Failing popsicle sticks, a bunch of small stock, about an eighth of an inch thick, and pointed will work.

Balance your "box" so that it's where you want it.  Then use the glue gun to glue the sticks so the point touches the roof.  When you take it off you'll have a series of points that define the curve.  Transfer these points to your actual stock, connect them with a batten, draw the line, then cut to the line.  If you really want to get precise, there are ways to cut the "rolling bevel" so the entire stock matches the roof.  You can use the sticks again to get the inside, transfer those marks to the inside of your piece, and use a block plane to roll the bevel.

Yes, boatbuilding videos will help.  You're basically spiling a plank, and there are a lot of ways to do that.  

[nopeda]

On 12/22/2025 at 1:12 AM, Don Z. said:

Balance your "box" so that it's where you want it.  Then use the glue gun to glue the sticks so the point touches the roof.  When you take it off you'll have a series of points that define the curve.  Transfer these points to your actual stock, connect them with a batten, draw the line, then cut to the line.  If you really want to get precise, there are ways to cut the "rolling bevel" so the entire stock matches the roof.  You can use the sticks again to get the inside, transfer those marks to the inside of your piece, and use a block plane to roll the bevel.

Thank you I might try that for getting the shape when it's time for the plywood. That roof slopes from front to back and side to side so there are a lot of different angles. I've made a rectangular frame as a base for now and then am making sort of anchor points where the bolts will go through to hold the frame about 12" apart. After they are all done might try filling in between them with 2x2s just as that much more support even if they don't always contact the roof if they're screwed and glued to the base it should add a good bit more strength. Then when the plywood is attached and screwed and glued to the base all around that will add a whole lot more support and when that gets covered with fiberglass cloth and resin it should add another lot more support and waterproofing as well. 

[legenddc]

I'm a bit confused. Are you planning to cut the metal roof of the van or are you just trying to put a tent or cargo storage on the top?

The roof on that has to be somewhat structural. I'd be concerned cutting it out would mess with the integrity of the van or at least the sliding door alignment.

[drzaius]

2 hours ago, legenddc said:

I'm a bit confused. Are you planning to cut the metal roof of the van or are you just trying to put a tent or cargo storage on the top?

The roof on that has to be somewhat structural. I'd be concerned cutting it out would mess with the integrity of the van or at least the sliding door alignment.

That roof is more than "somewhat structural". Unless proper engineering is done to ensure that the raised addition will be able to fully capable of taking the original roof's load. This project is just a disaster waiting to roll on down the road.

Sorry to be so negative.

[Coop]

I doubt seriously that he’s going to put a sunroof where one shouldn’t be.

[Mark J]

Give some consideration, too, as to how heavy the camper roof will be.  It might significantly shift the center of gravity up.  

[Von]

Sorry if I missed this, but have you considered a standard set of roof racks (two horizontal bars held up by turrets which clip to the sides of the roof)? These would seem to give a level surface to build off.