Friday, September 22, 2023


Ask Dave: What is the best method to insulate my Class C RV’s front cap?

Dear Dave,
I would like to add additional insulation to the nose cone over the cab in my Winnebago Aspect to reduce the amount of heat behind the forward cabinets. What would be a good choice of insulation to fill in the space behind the cabinets? Currently there are only wire harnesses just laying over the cab top, so I don’t believe there is an issue with covering them. During the summer months the interior cabinets get very warm. —George, 2017 Winnebago Aspect 27K

Dear George,
I am a little surprised that there is no insulation there to begin with, as Winnebago has been very good at that over the years. However, I’ve learned to never say never, or at least when it comes to the RV industry!

The front cap is a form molded fiberglass component. Thanks to Winnebago’s excellent owner resource section on their website, I was able to get some photos and 3D drawings. Here is the 30J model, which would look very similar to yours.

Inside there would be a center TV and side cabinets.

Since you indicated there is a wire loom laying over the cab top, I assume you were able to remove the TV to gain access to the cavity behind? Here is the 3D drawing of the cab.

And here is the back side of that.

From the drawings, it does not look like there is access to the actual cavity to the cap, just the frame of the cabinets. There is a small square cutout that you can see in the lower left of the cabinet. It would be best to have access to the back side of the actual fiberglass material of the overhead cap to add insulation.

Several types of insulation

There are several types of insulation that can be used depending on the access you have. If it is wide open, the best, in my opinion, would be to add a spray-on expanding foam insulation. We did this to an older model Itasca as it had several wind and moisture leaks. We removed the cabinets to be able to get to all the areas.

I have talked with several owners of older coaches that just shoved batt-type insulation in the cavities. However, you want to be careful of this method as it could produce moisture from humidity. It’s best to apply a vapor barrier if possible. Plus, you have the fact that it is itchy—I hate working with it.

Another popular insulation is the foil backed type that either has the air pockets like Reflectix or the thicker versions such as Roxul.


This thicker version will give more insulation and is moisture resistant. The Reflectix also requires an air gap to give efficient insulation. The Roxul is easy to work with and can be applied with a non-toxic adhesive. Check with your home improvement stores for an adhesive that can be used for hanging wallpaper or fabric inside. Since you have such a tight space, most spray adhesives will have harmful fumes.

I have seen other brands at home improvement stores. Just make sure they are moisture resistant as well as mold and mildew resistant.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


  1. Additional insulation? How about adding insulation. Mine had NONE. I called a friend and we removed the front cap Easy. 2 screw guns and #2head drivers. Remove the thun plastic that covers the screws. Get some putty knives to get under the trim that holds the cap. Scrape the mastic until the trim is loose and remove the cap. we used regular dow corning fiberglass, thickness as needed. Get some new sealer. Comes in 25 ft rolls i believe. Also some Dicor self leveling sealant. Couple tubes. Add insulation and put back together. The two of us did this job in about 6 man hours. Saved a lot of money heating/ cooling. Something Starcraft should have done in the first place. They saved what, $3!

  2. 48″ x 10ft
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    4.6 out of 5 stars2,404 Reviews
    INSULATION MARKETPLACE SmartSHIELD -3mm 48inx10ft ReflectiveINSULATION roll, Foam Core Radiant Barrier, ThermalINSULATION Shield – Engineered Foil
    in Weatherproofing Window Insulation Kits by INSULATION MARKETPLACE
    INSULATION MARKETPLACE SmartSHIELD -3mm 48inx10ft ReflectiveINSULATION roll, Foam Core Radiant Barrier, ThermalINSULATION Shield – Engineered Foil

    I used the above with some stick-on Velcroto insulate the walls of all the exterior cabinets In our LTV. Made a huge difference in temperature throughout the coach


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