You should only install reflectix insulation in your van conversion if you include an airgap for the reflectix to work properly.
Reflectix insulation is an excellent insulator and acts as a radiant barrier and a vapour barrier, but you must install it correctly within you campervan insulation system. Otherwise, you’re doing more harm than good.
What is reflectix?
Reflectix is bubble wrap surrounded by a layer of foil on either side.
Sometimes, there can be foam insulation instead of bubble wrap, but the important part to note is the layer of reflective aluminium foil on both sides of the material.
Reflectix is often used in houses as an insulator in lofts, where they have plenty of space.
This is for a very important reason…
How does reflectix work?
Reflectix insulation is a radiant barrier and works by reflecting infrared heat and stopping infrared heat from being emitted.
A radiant barrier helps insulate the van by either keeping heat in, in colder weather, and out, in hotter weather.
If your van is completely empty, and you stand inside during a summer’s day, the heat you are feeling is radiant heat.
The metal walls absorb the heat from the sun and radiate it out into the air, which hits you.
In the winter, if you put a heater inside an empty van and turn it on, then go outside, the outside of your van will now be emitting heat.
Both of these scenarios are what we want to avoid in our van.
In the summer, you want the inside of the van to be cool, not roasting hot. In the winter, you want any heat you generate to stay inside your van.
To combat this, you can use reflectix.
We’ve done a video showing how this works, but in short, infrared heat hits the reflective material, and 97% is reflected back into the air.
Similarly, if reflectix insulation is placed on a heat source, it will only emit 3% of the heat out to the air.
Reflectix insulation must have an air gap for it to work properly.
This cannot be overstated enough. If you install reflectix without an air gap on at least one side, instead of reflecting heat, it will conduct heat (heat transfer between solid materials).
Standing in front of a radiator at home, the heat you feel is radiant heat. However, if you touch the radiator and make contact, there is no airgap, and now heat is being conducted from one solid (the radiator) to another (your hand, ouch).
This is not radiant heat transference anymore; this is conductive heat transference.
How to install reflectix insulation in a van
To make reflectix insulation work in a van conversion, you must create an air gap between the reflectix and either the wall cladding or the van wall.
There must be an air gap on one side or the other. Whichever way you do it, it doesn’t make a difference.
Or, you can put your insulation, then wall framing, then reflectix, then your wall cladding.
No matter which way you put the reflectix, you get the same result, and the inverse is true in the winter, when you’re trying to keep your van warm.
What NOT to do: If you sandwich the cladding, reflectix and van metal all together without any air gaps in between, you are actually making the system work against you. You will increase the rate of heat transference by sandwiching the reflectix because the heat will now be conducting through the whole system, since there is no air gap.
If you can not ensure an air gap for your reflectix insulation to function, then it is best that you skip installing it.
Reflectix as a vapour barrier
Reflectix insulation is not only an insulator but is also a moisture/vapour barrier. A vapour barrier stops moist air from inside your van from moving through the walls to the cold van metal, where the temperature difference will make it condense.
Since the wall cavities are full of insulation, there is very limited airflow, and the moisture will have a hard time escaping.
Eventually, the cavities will get saturated with water and that leads to mould and rust inside your walls.
For a moisture barrier to be effective, it has to be perfectly seamless and sealed.
Realistically, that ship has sailed as soon as the thought arises in a van conversion – even if you use foil tape to fill in all the little gaps and seams.
You are in a vehicle that is going to be moving and vibrating. The van metal expands and contracts with temperature, so eventually, the tape may get minor tears, or a few scuffs, and moisture may get underneath the tape.
That is why some people elect not to put any reflectix on, because of how unlikely it is to make it so seamless, and they would rather share the airflow of the living space with their wall cavities to try and vent the moisture in the walls back out into the living space.
Is installing reflectix insulation worth it?
We believe reflectix insulation is worth installing if you do it properly.
Reflectix is a radiant barrier and a vapour barrier. You get both properties.
We noticed a huge difference before installing reflectix insulation vs. after installing it, even with all our other insulation in place beforehand.