Keeping Things Warm: Insulation Upgrades For Truck Campers

In a recent article, we wrote about a few weaknesses we found in the insulation of our Northstar Laredo SC truck camper. Shortly after that article was published, we received an email from long-time reader, Pete Horneck, who said he had a similar experience with his Northstar Laredo and that he took several steps to correct those deficiencies. This informative article outlines the insulation materials he used and the steps he took to correct them.

I love winter sports, so I use my 2011 Northstar Laredo SC truck camper all year round. As soon as the colder temps came around this winter I noticed several drafts—sitting at the dinette I could feel cold air tumbling out of the cabover. In addition, on windy days a breeze could be felt in the galley, and the floor was definitely cold in bare feet. I was certain improvements could be made, so I set out to do what I could to make the camper more comfortable. As it turns out, most of the things I did can also be of benefit during the summer if you have an air conditioner.

First, I needed to identify the sources of the drafts. I scoured the Internet forums to see what other owners of my camper had done and even got some suggestions from the manufacturer that included adding insulation under the floor, so I had a good idea where to start. I picked up a cheap infrared thermometer and waited for a day well below freezing to take some readings. The biggest air leaks were coming from around the DC compressor refrigerator, the shore power cord door, and the vent near the batteries. Then I went to work with the thermometer, shooting temperatures all around the camper, including inside all the cabinets, nooks and crannies. The lowest temp readings were on the sheet metal enclosure for the LP tank and the single-layer skylight in the wet-bath.

Armed with this info, I starting researching various types of insulation to see what was best for my application. I had used Reflectix insulation in my last camper in a number of places, including under the mattress. Everything I read seemed to indicate it worked best as a radiant barrier with sides exposed to reflect infrared energy, and that it was not as good when attached to or sandwiched between materials. Fiberglass batting was already installed around the compressor refrigerator, but I could feel the draft blowing through it. Rather than using more fiberglass batting, I opted to go with rigid block foam insulation instead, and of those the foil-backed polyisocyanurate seemed to have the best R-value per inch, plus it was lightweight. I had some 1-inch pink insulation board left over from a project, so I decided to use that also.

In order to control the cold air coming into the cabin, I went after the air leaks first. There’s a vent strip along the front lower edge of the fridge for ventilation if the fridge needs to draw cooling air from the cabin. My DC compressor refrigerator draws air from a rear vent, so I taped over the front vent holes. Next I cut a piece of the pink board to fill the shore power cord door opening. This is a press fit, so if I want to use the door it is not a big deal to pop the insulation out. Lastly, I plugged the vent near the batteries because I have AGM batteries that don’t need to be vented.

Now that I could control the amount of fresh cold air entering the cabin by using the roof vents, it was time to focus on keeping the warm air inside. My camper doesn’t have a basement, per se, but it does have 1×4 wood framing underneath that creates cavities that can be filled with insulation. I carefully measured the cavities underneath. Then I used a small circular saw to cut pieces from the 4×8 polyiso sheet and pressed these into the cavities. If you decide to do this, too, be sure to allow openings for any drains. My research indicated diminishing cost efficiency as you add layers of insulation, so I stopped after adding the 2-inch layer to the manufacturer’s 1-inch polystyrene board layer. However, I had a scrap the perfect size to fit underneath the battery area, so I doubled up there knowing how batteries lose power as their temperature goes down.

Next, I tackled the insulation around the DC compressor refrigerator. To do the job right, the refrigerator needs to be removed from the cabinet. Doing this also makes the job a lot easier. I cut pieces of the 1-inch thick pink board for the sides, which were mounted on top of the cavity, so when the refrigerator was replaced, it was a tight squeeze. In hindsight, I should have cut a piece to place under the fridge, too, and maybe one to place on the back of the refrigerator.

I was able to access the propane box through a small cabinet and a drawer opening. I cut pieces of the pink board just small enough to fit through the openings then glued them to the box with silicone.

I cut pieces of the 1-inch pink board for the two wheel well door openings. Again these were pressed into the openings so that they can removed if needed.

I have two roof vents, so I bought one of those RV foam insulator cushions from the RV store to stuff in one of the vents after removing the crank handle. The insulator cushion kept squeezing itself out of place, so I secured it by placing small velcro hook-side tabs on the sidewalls of the vent trim. They keep the fleece firmly into place.

I wasn’t willing to give up any headroom (or moonlight) in the wet bath, so I didn’t get a fleece cushion for the skylight dome in there. However, I did notice a big improvement by closing off the wet bath with the accordion door.

Lastly, I used some leftover Reflectix to cover the two entry door windows and the pass through window to reduce heat loss through them.

How did everything turn out? Unfortunately, it’s hard to get identical conditions to evaluate my results, but these are my impressions:

• I still feel cooler air spilling out of the cabover. The cabover has a big surface area, so the space is a victim of its shape and subject to a lot of cooling, especially if it’s windy outside. Other than possibly covering over the windows and Heki Vent there isn’t a lot more I am willing to do. Some people place insulation between the cabover floor and mattress. I put Reflectix there in my last camper, but I started to get mildew on the bottom of the foam mattress caused by condensation. In this camper, I used Hypervent instead, which allows air under the mattress and haven’t had the mildew problem at all.
• Cold air entering from the fridge/shore power door/battery vent is now negligible. With additional insulation added to both the refrigerator cabinet and the adjacent propane box, drafts coming out of the area have been significantly reduced.
• Reducing the cold air hitting the floor, combined with significant insulation underneath the floor, means that I can walk in socks pretty comfortably, but sheepskin slippers are better!

In conclusion, the improvements to insulation in my Northstar Laredo SC have paid huge dividends. Considering the low-cost and weight of the insulation, the small amount of time and effort, and the relative ease of installing it, I’m quite satisfied with the results. Winter camping in my camper is much more comfortable now. And if you have an air conditioner, they will pay double dividends.