Floor Insulation

Considerations

Many decisions that follow are based on my 2016 Ford Transit LWB (Long Wheel Base) and Medium Roof. Keep that in mind, when applying this information to your specific vehicle model.

The general amount of insulation is greatly influenced by the location(s) where the RV has its primary use. If you live in one of the northern or plain states or Canada and you’ll use your van mainly on ski trips or other winter outings, insulation (and heating) play a bigger role. Thicker insulation materials, air barriers and window protection are needed to keep your house on wheels livable.

I live in Florida and plan to use the van primarily in warmer climates, such as the South West. The trips I’ll make, will include all the states and Canada, but mostly during summer. I’ll be following the sun, meaning that when temperatures go down, it’s time to pack up and move further south.

In my years of experience, I know that you cannot avoid colder temperatures or even freezing entirely, so a good heater is at the top of my list, but in general my focus is more on ventilation, while moderate insulation should suffice.

That said, my number one issue, that directly relates to the amount of insulation, is the interior height of the van. Most private and commercial upfitters choose a high roof vehicle for their conversion project. In most cases, they have room to spare to implement all their ideas. My medium roof Transit has more limitations. I’m of medium size and can walk straight up in the empty van without any difficulty. That changes after applying a floor and ceiling to the interior.

With a ½” sub-floor on top of the floor ribs, there’s less than an inch left for a ceiling and a finish floor. That leaves enough space for insulation between the ceilings bows, but almost none at floor level. Thankfully, in my opinion, insulating the floor is less important than shielding the roof of the van from the sun’s rays. I decided to fill the spaces between the floor ribs with foam board and use a spray foam for the remaining cavities between the ribs and the plywood sheets above it.

The type of material I choose, was Poly-Iso (Polyisocyanurate). It has the highest R-value per inch of any rigid foam board insulation and is locally available at very reasonable prices. Don’t use ordinary polystyrene, that has a much lower insulation value. An aerogel may offer the best in thermal performance, but is exorbitantly expensive. Than there is the popularity of Reflectix, a material that on its own, has little or no R-value and where long term performance may be uncertain.

Before you start working on the insulation and/or sub-floor, you should consider, whether any electrical cables or plumbing lines should be installed prior to laying the floor. In general, that’s not advised as these features can never be accessed at a later time, without major modifications.

The actual work is quite simple and uncomplicated. Cutting with a sharp utility knife and a carpenter’s square is easy. The Ford Transit however, has a lot of grooves to fill, with many different lengths and widths and it took me the better part of the day, to get all the pieces together.