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Question Of The Week

The First Verdict on Waterproof Campers

This week we asked our readers about different ways we could improve the roof, side, and underbody seals on our truck campers using spray-on coatings and tapes.  We wanted to know if we could collectively find a way to waterproof campers.  The responses are fascinating.

Evidently, we’re not the only ones who have thought about this topic.  Finding sealant on your jeans – again – will do that.  So will finding a break in a seal you repaired a few months prior.  As I have said before, there has to be a better way.

This is going to be a long term project.  As truck camper owners ourselves, we are excited to try a number of possible solutions, and write about our experiences.  That said, we need to do more research, and it’s going to take time.  Since we love our truck camper, and want it to last, we are ready for the challenge.

“Hi Guys!  I have no research whatsoever to enlighten you with, but you did get me thinking about this subject.  In my opinion, the sealants that we have available to us are of good quality.  I believe flex and vibration are what actually causes the sealants to fail.

The flex and vibration in truck campers is caused by at least two things.  The lightweight construction demanded of RVs allows them to flex, almost by design.  How can a roof hatch physically seal to a panel that is almost constantly flexing?  It’s also moving due to temperature changes, road vibration, and the entire truck camper box being distorted by road bumps and the twisting of the truck bed.

Current truck camper tie downs have several mounting points; truck frame mounts, or bed mounts, and sometimes a combination of both.  Truck frames flex a lot!  Truck beds are even worse as they are mounted to the flexing frame by flexing rubber mounts.

Our truck campers are being pushed and pulled in all directions during normal driving conditions, and its wood or aluminum-alloy framing cannot keep the exterior panels from flexing.  I think rubber gaskets or O-rings are the closest thing we’ll find for an engineering solution (think roof mounted air conditioners) to this kind of flex issue.

We have a lot of custom sheet metal details in our house.  These elements need caulking where they seal, and where fasteners go through them.  It’s not so different than RVs, but admittedly the materials are sheet metal and wood, or sheet metal and steel with screws/nails.

That said, I have thirty years of experience sealing this beast and by far the best stuff is Vulkem 116 Polyurethane Sealant made by Tremco.  It’s available in a variety of colors.  Now, I’ve never tried it on our truck camper, because Truck Camper Magazine told me to buy Sikaflex 715 and 521 sealants!

If you’re going to try any experimentation, you might try the Vulkem caulk.  It’s a lot more viscous than the 715 and much different texture than other caulks, so really special stuff.  Just my two cents.  Keep up the good work!” – Bruce and Kathy Allison, 2000 Ford F350, 2012 Adventurer 910 FBS

“Having spent a large amount of my life outside in everything from deserts, to rain forests, to full monsoons in steaming jungles, staying dry is always a challenge.  One of the things I learned many years ago is that waterproof is not going to happen.  Designing to prevent water intrusion one must never forget the cardinal rule; that which can be kept out, also keeps in.

I have lost more to water retention than I have from water intrusion.  If you want to keep it dry, then you must be able to dry it out when – not if – it gets wet.  Without passing judgment on the application of Line-X on the Palomino, caution is advised or it becomes a container for water.

The key is to plan for mitigation when water is ingested.  For truck campers this begins at the design and material phase.  Use no fiberglass or other wool-like insulation.  Go with closed cell foam.  Choose an aluminum superstructure rather than wood.  In general use materials that do not absorb liquids.

If wood must be used, then it should be marine grade or waterproofed wood.  By design, you should avoid forward facing windows.  Rain at sixty-five miles per hour will find its way in.

Another major issue on truck campers are the seams on the front nose.  I can find no reason why the nose piece could not be a solid piece or bonded seams.  I have driven fiberglass cars since the 60s and never saw the ugly seams used like in the truck camper business.  I have never had a Corvette leak water through its body.

In addition, the aerodynamics of a truck camper are on par with a barn at best.  Water is often invited in due to poor aerodynamics.  This is 2015, not 1965.  Its time the truck camper industry looks at proven materials and designs to bring truck campers into the 21st century!” – Don Pryor, 2015 Ford F350, 2008 Arctic Fox 1150

“While my response does not specifically address your questions, I would like to weigh in on the topic.  Simply renewing the caulking on an older camper is really only a stop gap fix.  When I find that a line of caulk has failed on my older camper, I frequently scape it off and remove the molding and its sealing.

The butyl tape under the caulked molding ages, dries out, and becomes brittle.  As this is the last line of defense in the fight against water intrusion in my camper, I feel it is important to keep the molding sealant in good condition as well.

I generally remove the molding, remove all the butyl tape remnants from the molding and the camper, and then reapply a suitable putty to the molding.  The molding is reinstalled.  After a week or so, when excess putty has oozed out from beneath the molding, I apply the caulk.  While this is quite time intensive, it also works extremely well.

Butyl tape tends to come in three-quarter inch widths, too small to cover many moldings with one strip.  Since it is so expensive, I no longer use it under the moldings.  I use Gardner-Bender duct putty instead.  It is a fraction of the cost of butyl tape, seems to stay flexible over a larger temperature range, and is available at many hardware and building supply stores.” – Arn Chamberlain, 200 Ford F250, 2004 Palomino Maverick 8801

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