Handling Moisture in RVs (updated
Phred Tinseth © 1999-2002 Reproduction permitted
Web site: http://www.phrannie.org
First things first.
You've got to keep moisture from getting in. After that, you deal with
what you make on your own.
Simple emergencies—broken window, tear in skin or roof, cracked
vent cover, etc. Most of these can be temporarily patched with
"aluminum duct tape." NO, not that grey cloth xxxx.
• Aluminum sealing tape is aluminum
tape with a peel-off sticky back (A-Seal) . If you
put it on a reasonably clean, dry surface, it'll work for months.
Every RVer should carry a roll—it's good for lots of other things.
• A roll of
If the problem is simple (a crack or
tear) aluminum tape will usually get you by.
More complicated emergencies—Bigger
stuff (like a shattered vent cover, antenna torn off, air conditioner
knocked loose by tree limb) take a piece of cardboard, thin paneling,
whatever's appropriate. Wrap it in aluminum foil. Tape seams. Stick
RoofSeal down around edge.
Lay/fold/bend alum covered cardboard over the disaster. Tape again.
"Regular" Leaks: Sealing, Caulking
If you can take something that's
leaking apart, do it. Then seal the mating surfaces and put it back
together. A "seal" can be a gasket (like under the air conditioner).
RV putty tape
(butyl sealing tape) for doors, windows, roof vents and the like or
RoofSeal for perimeter seals.
Smearing globs of caulking all over everything is not sealing—and it
doesn't work (DO NOT USE SILICONE SEALANT).
"Caulking" is something you reserve
only for things that can't be fixed properly in the first place (or
that you're too lazy to fix properly). Caulking is also "insurance."
First you seal something (like a roof vent); then, for insurance, you
caulk it to keep moisture from getting at the seal that does the real
"Coating" is the last step. After
you've applied your sealing material and assembled things properly
(without a lot of holes and gaps) and caulked (if necessary); then you
coat the whole surface if appropriate.
Products are here.
Coating can be as simple as paint
(prevents weathering, ultraviolet decay, rust and makes the thing look
decent); or more complex (elastomerics that provide more durability
and insulation) or more complicated and expensive (like custom-fitted
vinyl sheeting—the so-called "Rubber Roof").
There's no point in doing any of the above unless you first repair
structural defects. Impossible to cover all variations, but here are
some that many people don't consider:
Roof Edges and Corner Trim:
In many RVs (especially older ones)
this is nothing more than a thin aluminum extrusion with screw holes
and a vinyl insert. Siding and roof sheeting raw edges are simply
butted together and fastened to the frame (usually just with staples).
A strip of
RV putty is laid over the joint and the trim strip is
screwed on. Generally, sufficient screws hit something solid enough to
hold everything together and compress the putty to prevent leaks (for
As time goes by, the putty gets
squeezed out (most rigs have this icky, dirty stuff oozing around
corners and windows). What remains dries, then cracks and gaps appear.
Water leaks in through the edges and screw holes.
The steel screws, staples, water and,
often, aluminum parts set up a corrosive (electrolytic) action that
compounds the problems of the water—that dribbles down through the
interior walls and rots everything out (including the flooring).
Insulation absorbs the water, loses all its capacity to insulate and
soon the whole frame gets wet and stays that way.
Water entering at the roof joint is
especially troublesome because it runs toward the lowest point in the
ceiling (usually at air conditioner, light fixture or a roof vent)
before drips start. The RVer then climbs on the roof and spreads caulk
all over above the place where (it seems) water drips—but not where it
came from—which does no good at all. The vinyl insert in the trim,
contrary to what people think, is not there to prevent water from
entering. Even though it's doubled over at the top, screwed down and
has half-a-pound of caulking smeared all over, it's nothing more than
a cosmetic to hide screws.
Roof Edges and Corner Trim
Remove vinyl insert and throw it away. You can get it new by the foot
at any good RV store. Trying to reinsert old stuff just looks crummy.
Examine screws as you remove them.
Generally, they'll be stock, #8 size, steel screws and some will be
corroded and rusty. If so, throw them away also. You can replace them
with better quality screws or #9 aluminum hex-head
(unusual oversize but deliberately made that way—sold in RV and
boating stores—to fill up previously used holes). Better are
stainless-steel screws (expensive, but can often be found in
electronics and "surplus" stores for about $3 a pound).
Carefully pry siding and roofing away
just enough to peek in and look for evidence of leaks. If you find
major damage, you can either: Put everything back together and get rid
of the rig; or, repair and reinforce (which you might want to do
anyway). My travel trailer had all of these "borders" replaced with
1-1/2" x 1/8" thick aluminum angle. Expensive, but it formed a "cage"
and the RV sort of held itself together. If you have some water damage
(but the thing isn't falling apart), you can get a product called "Git
Rot" in boating stores. A liquid you mix and squirt or inject into
wood, it chemically converts wood cellulose into an epoxy-like
material. (Nice for treating exposed wood behind motor home skin.)
Clean off the old RV putty. "409,
Simple Soylent Green" and the like, all work well with a scrubbing pad
like you use on PTFE non-stick pans. You'll remove the vehicle wax too, but
after this job, you'll need to rewax (maybe refinish) anyway.
Butyl rubber sealing tape (RV putty tape) is a gray material in rolls of 3/4" or 1" wide
with a crepe-paper backing (it's often called monkey-poop).
TIP: When using any kind of this
tape/sealer, it will tend to stick to itself and the backing. Most
annoying. Avoid this by putting it in the freezer for 10 or so minutes
and it's a lot easier to handle (and will still stick just fine).
Once all is done, excess rusty
staples and tacks replaced, etc., (you can get stainless-no corrosion
staples or tacks in large upholstering stores), carefully reapply a
strip of the good putty tape mentioned above. (Don't try to skimp on a
$ with 3/4" stuff, get the 1" wide stuff (or wider where applicable).
You can always trim off excess, but you can't easily add on extra.)
Replace molding and put it back together.
As you replace screws (with better
grade as above), note previous "bad" holes (with simple pencil marks).
There's no point putting new screws in non-existent holes. Just drill
a hole near to it and seal the old one. Similarly, if you're in a
suspect area, drill new holes and add more screws.
An Important Step:
• Before you insert a screw, drill a
pilot hole (if new) and fill the existing, or new, hole with caulking.
• You don't need a big gun full of
crud for this. You definitely DO NOT need the cheap, ordinary
"silicone" caulk used by most RVers. Sun (ultra-violet) light decays
it. It won't adhere to many surfaces and it's hard to remove if it
• What you need is the
"Quick-Leak-Check" brand or something similar (that doesn't dry out
and can be "unscrewed" from later) in a small tube that you can handle
When you put in new screws, DO NOT
guide. (Especially with aluminum screws that will easily snap
off if overtightened.) All you want to do is get this largely cosmetic
strip "snugged up" nice and firm. The minute you hit the road, the
whole rig is going to start flexing. You want it to be allowed to flex
without opening new holes.
Finally, insert new vinyl flex trim.
• Do not let it get stretched out too
much. It will eventually reassume its natural length and you'll be
left with gaps.
• Look around your RV park. Note even
new RVs with gaps in trim because idiots installed it. (A new home for
• Better, lock it in place at the top
or an end with a screw and leave a few inches of slack at the other.
It'll look funny for a few weeks (what do you care?) but you can trim
it and screw the bottom down after it's settled in position. Do you
now caulk the edges? No, you shouldn't really need to if you did the
Awning supports are difficult because
they are almost never sealed properly. Installers usually (but not
always) make a big deal out of locating structural members inside the
walls for attaching the (main) end pieces (upright supports). Then
they just screw them in through the outer skin without any gasket,
backing sealer or caulk in the holes. Further, corrugated aluminum and
fiberglass skins are usually badly crushed in the process. The thin
moulding strip that holds the awning fabric against the wall (along
the top) also has no backing and the many screws are just run through
pre-punched holes with no effort to locate what other structural
members might be behind there.
If you're going to have an awning
installed, you might get an installer to do the job right, but it's
unlikely. Usually they'll agree with everything you say, then ignore
you and do it "quick and dirty." You'll be better off getting a friend
or two to help. It's easy if you read the instructions. It'll take up
to two days (if you do it properly and spend some time figuring out
where the backing behind the skin really is) instead of a couple of
hours; but you won't have any leaks and it will be secure. (A friend
and I were sitting at the RV park when the truck showed up -- from one
of the really, really big RV stores -- at a neighboring site. The men
got the job done quickly -- too quickly -- and while they putzed
around measuring the outside, we never saw them go inside the RV. We
knew we were in for a treat and sure enough, when the techie reached
up with the hook and pulled on the awning, it came right off the RV.)
Awning leaks are really nasty,
because water goes into the inner wall and usually isn't detected
until it's done severe damage. Sometimes water will work its way down
the inner wall (through all those screw holes that aren't really
screwed into anything). Often, water from awning leaks eventually
works its way into the inner RV wall through a window frame. Most
RVers then assume the frame is the source and spread caulk all over
the window and wonder why it won't stop leaking.
If the awning is already installed,
removal and reinstalling is a real chore. This is a case where you
might get away with using
M1 Sealant if you do it right. Remove each awning
strip screw (just one at a time), fill the hole with caulk and
reinsert a better screw as above.
Most of these screws only go through a thin aluminum or fiberglass
skin. If you tighten them too much, you'll just make a bigger hole.
You can repair with an insert or pop rivet, but you don't want to
If you're using a
quality sealer in
an easily-handled tube with a fine tip, you can also apply just a bit
around the edge of each screw head. Examine main support bolts before
diddling with them. You may be able to remove, caulk hole, and replace
one at a time, or you may be able to partially unscrew and apply caulk
to threads and retighten.
Carefully caulk around the edge of
support arm plates. Don't try to apply huge globs at one time. Try to
get a thin bead into, not just all over, crevices; then go back and
add more later. Similarly, apply a thin bead of caulk along the top
and bottom of the long horizontal strip.
Door and window frames
Door and window frames are fixed like
the above with some added steps. They're made to be opened, so joints
aren't going to be weather proof. In good windows, a very small amount
of water will enter, but it should remain on the glass or frame and
exit through small "weep" holes at the bottom of the frame. Weep holes
can't work if plugged with dirt/caulk or you deliberately plug them to
keep out bugs. Some condensation will also form on glass and metal
frames, but a well-constructed window should drain this through weeps
Often, windows leak around the edge
of the frame simply because the manufacturer cut the hole too big. In
the worst cases, the siding and frame don't even touch (once again,
you'll see enormous amounts of caulk smeared around because people are
too lazy or inept to remove the window frame and do the job right).
One way to fix this is to: Remove
window and frame. Treat any rot with "Git Rot." Cover the edges of the
hole (after everything is dry) with aluminum duct tape, overlapped, so
the inner framework is completely covered and the tape overlaps the
inner and outer wall a bit. The idea is to prevent moisture from
getting into the inner wall and insulation. In case of a future leak,
water will either run back out to the outside, or onto the inside,
finished wall where it will easily be seen before it does any damage.
Once this is done correctly, replace window and frame. It's easy to
trim off excess putty and, then, with an "X-Acto" or similar sharp
blade, score the aluminum tape and peel off any that shows.
Another way to do this fix is to:
Treat rot then shim/fill the inside of the hole as above and apply the
aluminum tape (or don't fill the excess hole and do the following—I'd
do both): Extend the outer lip of the window frame itself by adding
1/8-inch thick by 1-1/4, 1-1/2 or 2-inch wide aluminum flat bar.
If you lay the pieces out carefully,
cutting edges to match, then
pop-riveting the pieces to the frame,
you'll end up with a big frame and crude corners. Once put together,
though, you can round off and smooth the corners. Automotive paint
stores sell a "self-etching aluminum primer" that bonds quite well to
new and old cleaned aluminum. If you clean aluminum properly and use
this primer, you can paint the frame with matching trim paint and it
will hold up at least as well as a new window.
Place the window in the hole, measure
carefully to the actual surrounding framework (there will be something
around the hole), then drill holes through the "new" frame and screw
it to the wall (not just to some inner frame that sandwiches the
newer, cheap windows together).
Before final assembly, seal the frame
with good putty tape, carefully applied, and you won't need any
caulking here either. To do a really nice job, since you're more or
less building a new window anyway, instead of just flat aluminum along
the top, use aluminum channel or angle instead. The thing will be
ultra-sturdy and you'll have a built-in rain protector.
Are done like windows, but because the whole inner frame is going to
be constantly banging in and out, you have to be extremely accurate in
measuring the placement, in making sure you have square corners and
securing the door assembly. Few RVs have door cutouts with accurate
corners, so most RV door assemblies are forced into place and are
crooked. Eventually, they get sprung out of shape and don't operate
well. Careful triming and shimming can correct this.
Luggage compartment doors
Luggage compartment and similar doors
usually leak because they weren't installed right. Remove them, clean
things up, patch holes and cracks, squeeze a bit of seal in screw
holes, carefully putty tape and reinstall. The bottom frame of
compartment doors should be kind of like a window, with weep holes so
water can run out. Unleveled rigs, cheap doors, and sloppy
installation can let water run in instead of out. This is especially
common in reefer pop-out doors.
Before you reinstall any of these
frames, examine the edges of the hole. Tubing, wood 2 x 2, ply and
foam—all will allow water to infiltrate. Again, treat for rot, use
aluminum tape and seal properly just as for windows. Don't do a sloppy
job just because the inside won't show as it does in the living area.
It doesn't do any good to have a nice living area if the compartments
underneath are rotting away.
If they were installed properly,
there will be a bit of pipe penetrating the roof with a sealed
flashing. Some, though, will be cut off flush with the roof and have a
large hole all around them and a big cap covering the whole mess. It's
obvious, when you look at one of these, that there's no way the thing
won't leak (so many RVs have wet closets).
If you cement a pipe coupling to one
of these flush-cut things you can add a bit more pipe. Then you can
cut a piece of aluminum sheet to cover the old hole and seal a proper
flashing around it. This isn't complicated but can require some
detailed work. For example; there's no pressure on these pipes, so you
can cut the coupling to slip up and down anywhere, carefully measure
its eventual height with an allowance for the thickness of a piece of
plywood that will go around the pipe, rest on the top of the coupling
and, in turn, support the aluminum patch. It's a little more work, but
it will be sturdy.
You do need some kind of lid
over/above sewer vents to keep out crud and critters and help provide
a draft to pull gas out of the tank. Most cheap RV store caps work
okay and you can get nice aluminum ones in building supply stores. The
"venturi" types in RV stores (look like a "T" with one end bigger than
the other) provide a better draft (so does a regular "T" and it's
To do a really nice job and really
ventilate a tank, consider topping vent pipes with "solar ventilating
fans." These look like mushrooms, have a 4-inch base (easily adapted
to any size sewer pipe), include a small fan and single solar cell.
Anytime there's sun, gas is being drawn out of your tank. Whatever you
cap your pipes with, make sure you coat it. Sunlight (UV) eats
plastic. Any coating, even plain paint, will keep your plastic from
rotting away. (This is also necessary down along the under edge of
your rig, in case you wonder why valves and fittings break for no
Air conditioners are really pretty
well designed. They have to be open to the elements, so everything is
just mounted on a big pan with drains in it and any water that gets in
just goes back out (or should). Lift off the outer cover (shroud) and
make sure the drains aren't full of crud. Weather, dirt, insects and
small birds and critters have easy access to the inner machinery of
the A/C. You should clean up the area once or twice a year.
While the cover is off, examine the
sheet metal box that covers the blower and air chamber. Seams usually
have a gasket or putty material to keep what little rain that might
collect from dripping down into the housing inside the RV. It's easy
to reseal these but in many cases all that's needed is to cover them
with the aluminum repair tape mentioned above, allowing moisture to
run down into the pan.
The whole air conditioner is held on
by nothing more than a large gasket and about four big nuts and
threaded rods reached through the A/C inside frame. (Has to be that
way because it moves and vibrates.) Most leaks occur at the gasket and
fortunately can usually be stopped by doing nothing more than
gradually tightening the main nuts/bolts, (one of the few things in an
RV that's usually easy to fix).
Replacing an A/C gasket is easy but
strenuous. Simply remove the main nuts/bolts, disconnect the wiring
harness, go up on the roof and lift/tilt the thing from one end, not
straight up. It's easier when two people do it and you should have
someone down below to make sure wires and such don't get hung up. New
gaskets don't need added putty and stuff, but you do need to make sure
the roof edges around the hole are clean and don't have gouges or
dents that water can run through.
Roof vents will leak, and the
slightest crack, that you can't even see, can suck water in, even
uphill, by capillary action from differing inside and outside air
pressure. This can give you a fit and can be complicated by a leak
from somewhere the ceiling panel joins.
Vent frames are usually putty-taped
to roofs and, some cases, you can see the putty seam from inside if
you remove the trim piece. If so, cram a putty knife in the crack
about 1/4" to 1/2" repeatedly all the way around. If the leak stops,
you might be OK. If it moves to a new place, you need to replace the
vent and putty tape, not just smear caulk all over.
For leaks between rafter and inside
ceiling, usually you can gently pry the ceiling panel down about 1/4
inch (look for staples and tacks) and hold open with pencils or
screwdriver tips. As you create this new low point in the ceiling, you
may get a whole bunch of water. If so, leave wedges there for several
days (might take weeks), no matter what other steps you take to fix
it, so it'll dry out. In some cases you might have to open a whole
seam. It's awful, and will look bad, but the alternative is major
surgery—which still might be necessary.
This kind of leak might be in the
vent also, You ought to remove and reseal or replace it (depending on
what you find). If the leak stops, you lucked out. If not (actually
simultaneously), you need to spend a lot of time on the roof, poking,
probing, pressing anywhere there's a seam, strip or something coming
through the roof -- the things mentioned earlier.
Replacing roof vents:
Replacing roof vents is easy—it's
just a lot of work. Usually the hardest part is removing caulking
(that shouldn't have been there in the first place) and getting the
screws out. Once the hole is open, scrape all the old stuff away at
least enough to clear the new vent frame plus an inch or so. Poke
around. Are the rafters wet? Why? Dry it out. Can you beef it up with
Git-Rot (above)? Or short pieces of aluminum angle in the corners?
Maybe build a lip all around the hole with aluminum? Lay the new vent
on the hole. Do screw holes match up? Do you want them to? Are the old
ones rotten? Actually, you're better off if new screw holes don't
match. But seal the old ones before installing a new vent.
Use a new, aluminum framed vent if
you can. If you use cheap plastic frames, you'll just have to do this
all over. Aluminum lids are best also, but some people want the light
through a plastic one (until the sun eats them or hail destroys them).
The "Lindeen" style vent covers/hoods can help a lot. Also, better RV
stores now carry an "unbreakable" plastic vent lid. Expensive, but
with a good warranty. I've used these for two years, through two
hailstorms, with no leaks or breakage (but no base-ball-sized hail
either). Once the hole is prepared, all you need to do is carefully
apply quality putty tape and evenly and firmly screw the thing down.
Do NOT over-tighten! All you'll do is create a new leak. Let the thing
sit there a few days. You can go back and tighten it a little more
later. Don't smear caulk all over the edge and screws either (that
comes later if needed at all). Don't be in a hurry to replace inside
trim pieces. Leave the hole bare awhile, let it dry and easily look
for leaks. Trim rings aren't much good anyway. Almost all of them just
slip up inside the vent frame. Leaks then drip down behind them, where
you can't see them, until they start coming through the ceiling. If
nothing else, when you install trim, run aluminum tape around the
inner hole (it won't be seen later) where rafters meet ceiling panel,
so that incoming water will run directly in and you can see it before
you ruin a ceiling. Better yet, make your own trim pieces-something
that funnels water in the right place, that matches your ceiling
better, that you can attach fans, decorative items or condensation
Lights, water entries, antennas,
Running and other lights, ladders and
grab bars, water entries, antennas and such usually have an ugly ring
of caulk smeared on them. They still leak and you can't see it and
moisture is in there rotting your rig away. Most of the cheap stuff,
like lights, can easily be removed and replaced with bigger (to cover
the crummy old edges), better (sturdier and some with gaskets) lights
at surprisingly low cost.
Patch old wires and screw
holes first. Look for scraped wires while
you're at it. If possible, fold wire down from hole, tape it in place
temporarily and seal the hole with good stuff like Seal Once. Build up
layers a bit at a time on big holes. Make a miniature awning out of a
small piece of aluminum tape. Rub it good above the hole, but just
sort of lay it over the hole and wire. (Anything that does get inside
the light fixture ought to run out the bottom.) If you're careful,
you'll be able to fold the wire back up a bit when installing the
light and further keep water from running into the hole.
Unless the light is top quality and
has a gasketed lens, don't try to seal the lens. The idea is it should
be a little loose so water will run out as fast as it gets in. You
also need to get in and change the bulb easily. Just a little dab of
sealer on opposite sides of the lens will keep it from falling off.
Depending on what kind of "skin" your
rig has, you can get nice watertight gaskets in automotive stores.
Also look for "threaded inserts" under various brand names in
auto and hardware stores. Some are compressed into place with a pop
rivet tool, other are screw-compressed with a wrench. There's a large
variety of thread sizes and depths. Once installed, you have a secure
threaded nut attached to the skin, not just a hole that keeps getting
bigger with age. Put a dab of "Loc-Tite" on the machine screw threads
and you can firm up things so they won't leak and can be easily
removed and replaced without screw holes getting ever bigger.
Shop for gasket material by
the square foot. Varying thickness and densities (so it can be
squeezed against uneven surfaces) are available. (I got a soft, but
water-repellent piece of vinyl, really quality stuff, from a shoe
repair shop cheap. They use it to resole moccasins.) A firmer piece is
perfect for behind a grab bar, luggage rack and ladder bolts,
antennas, and flag holders. Computer "mouse pads" make a nice gasket
Fender well covers:
Fender well covers are a key source
of interior wet rot that most people never think of—until they're
digging around under a cabinet and find a huge mass of green crud
growing there. First, remember that these things, like wheel covers,
are strictly cosmetic and often not needed unless the fender well is
really crudely built. Most people automatically run a bead of caulk
along them. It does absolutely no good and just makes the thing hard
to remove when you have to work on your rig. And more time to remove
it = more cost if in an RV shop. If you must use these things, don't
try to seal/caulk them. Instead, use the threaded inserts mentioned
earlier—no leaks and EZ on-and-off.
However, the edge around the actual
wheel well, where side, bottom and wheel well meet, might have really
shabby seams. Putty tape and aluminum angle can usually leak-proof
these. It won't look too swell, but fender well cover will conceal it.
Wire and cable entry:
Wire and cable entry through a roof
or wall: Usually, some fathead drills a hole, pokes the wire through,
then smears on huge globs of silicone. How sad. I once watched a
satellite TV "technician" adequately install and seal the main
antenna. He then prepared to drill a hole right through the roof
alongside it and poke the wire through with the intention of running
the wire, exposed, along the ceiling and down the wall to a shelf.
What an idiot! The refrigerator roof vent was only a couple of feet
away. All he had to do was enter through the side of the upper reefer
vent cover (no leaks) then run the wire down the back corner behind
the reefer and through the wall to the very same shelf. (He got very
upset when I pointed this out.) Was it just too much time and trouble
to snake the wire around some corners? Probably. Did he just not give
a damn? Probably. Is he still doing this (like the manufacturers who
run wire and pipe aimlessly through your valuable cabinet space)?
Probably. I find that it's very profitable (and most enjoyable) to
spend an hour or so sitting on the roof, drinking beer and just
thinking about the possibilities before I start chopping holes in
See above for considerations on
running cable to them. A couple of modules/panels, regulator and
cable, etc., are going to cost over $1,000. Do you want to install it
sloppily and create leaks? Sit on the roof, drink beer with a couple
of knowledgeable friends and make a plan.
(Good place to hide out from spouses
for awhile too.) Notice, also, I said spouses, not wives. I find women
are as adept at this kind of abstract stuff—maybe more so—than men.
Men want to jump right in and start chopping holes. Then they have to
do it all over again later. Women don't know they're not supposed to
be involved in this, so they do it anyway, paying attention to
planning and detail, and usually do it better—and that's no horse
Consider that a solar module weighs
about 10 pounds, whereas an air conditioner weighs about 150. If the
A/C is held down by only four bolts, do you really need some massive
structure for a few solar modules? No. (See RVers' Guide to Solar
Battery Charging, Noel and Barbara Kirkby, aatec Pubs., for details.
Kirkby, owner of "RV Solar Electric" and the most knowledgeable of
dealers, also has a solar "Systems Installation Guide." Only $5,
refundable with a purchase. You need to buy it even if you get your
equipment elsewhere. No other dealer provides—and few know of—the info
in here that will allow you to install solar panels securely, with no
mess and no leaks. Most highly recommended.)
RUBBER ROOFS (followed by more on
other roof coatings)
Possibly (but arguably) the best
is a professionally-applied EPDM sheeting (the
so-called rubber roof). It's expensive, but it is, in effect, a new
roof—IF INSTALLED PROPERLY! Careless installation, even by a
professional, can end up with you being even worse off. To install it
properly, everything is first removed from the roof and replaced when
the job is done. The problem with this is that when basic problems are
not repaired before the new roof is laid on, the new roof isn't
affixed properly, the EPDM ROOFING is cut improperly and things are replaced
and not sealed properly as described above, you're right back where
More on Rubber Roofs:
I'm getting lots of letters from readers on the subject. I expect the
reader queries will increase as more and more used RVs with rubber
roofs are passed on to others.
"A critical point: It is critical that
no petroleum-based solvents, harsh abrasives, or citric-based cleaners
be used on rubber roofs! Doing so can cause irrepairable damage. (And
seems to be the real cause of most roof complaints, followed closely
by sloppy installations. (What do you expect from installers working
for minimum wage?)
Petroleum-based solvents are
especially damaging. They can penetrate the membrane and dissolve the
adhesive underneath. The result can be bubbles or even large, loose
Bubbles should generally be left alone, unless there are a great many
of them, which indicates a more serious problem (like extensive use of
petroleum products or a poorly installed roof).
If you insist on fixing bubbles (and
you shouldn't), make sure you use only sealers that specifically
state: "butyl rubber" caulking/sealant.
There are a lot of sealers, caulks
and care products that have something like "Okay for rubber roofs" on
the label. Do not accept that as a fact. Use
When attempting to fix (flatten)
bubbles, don't just start cutting away. Get some disposable medical
syringes from a pharmacy. Load one with some of the butyl rubber
sealant, carefully inject some and carefully massage the bubble. Once
it's flat (this can take a lot of massaging, hey, I warned you),
put a piece of cling wrap or wax paper over it and put a weight on it
until dry. You might be successful and might not.
One place you can successfully use
the butyl rubber sealant (and really do some good, rather than just
screw around with bubbles) is at the edges of the roof membrane. Roof
vents, plumbing vent pipe holes, roof edges under trim strips, air
conditioner openings, etc., are all subject to loosening at the
membrane's edges. (This is often caused by a sloppy installation.)
Refrigerator roof vents are
especially troublesome. Installers often cut the opening through the
membrane rather casually. They then fold it over the edges of the vent
hole and don't adequately secure it. Over time, and with the heat that
flows up through the vent, air flow can be restricted (and it doesn't
take much to cause the all-too-common complaint that the reefer isn't
RV manufacturers do (frequently) an
absolutely lousy job of installing refrigerators. Poor ventilation is
(experts say) the primary cause of refrigerator failures. I recently
heard of a refrigerator ruined because the manufacturer simply cut a
hole in the roof over a reefer and let the rubber-covered plywood drop
on top of the reefer. No venting equals no reefer. You might want to
see what's really under your roof vent.
Maintaining the rubber roof:
Mild dish washing detergent (Dawn, Joy, etc.) should do the job unless
parked under really grody trees. Use a mild-bristle brush. Do not use
harsh abrasives or a stiff brush. A sponge is okay for scrubbing, but
a brush is needed when rinsing. (Using a sponge when rinsing just
smooshes the dirt around and doesn't get rid of it.)
Full-strength household bleach is
good for stubborn stains (but don't slop it all over, or it will run
down the sides and screw up your wax job).
Dicor makes a safe cleaner. Their
"RC100 Dicor Synthetic Roof and General Purpose Cleaner" works and
attacks stubborn stains when used full strength.
Mineral spirits can help with
stubborn stains, but, you can't spread it over large areas and must
work very fast (spot clean and flush it off quickly) or it can
deteriorate the membrane.
Another good protectant is "303." It
will not harm rubber roofs and will keep crud from accumulating, but,
Dicor insists it isn't really necessary. (Does this remind you of the
days when Andy Granatelli sold STP? He finally admitted it didn't
really do any good, but didn't do any harm either.) What the heck,
it's your money. "303" can be used for lots of things.
Something to think about
A word often used in discussing (so-called) rubber roofs is
"if." As in rubber roofs can be dandy:
If the basic structure (rafters, etc.) is sound.
If the ply underlayment is sound and of adequate thickness.
If the rubber sheeting is carefully laid on without gouges,
If done without careless trimming around things that penetrate
If done without any nail/screw heads/wood splinters and such
that they'll eventually penetrate the rubber from the underside, etc.
If rubber adhesive is properly applied so bubbles won't appear
edges won't come loose.
If rubber material is properly folded over roof edges,
and moulding is properly applied.
If the RVer doesn't screw things up by gouging, scraping, etc.
If the RVer uses the specified mild-detergent cleaning agents
uses a petroleum-based cleaner or protective coating.
If the RVer reads the material that accompanies the roof and
that there will be discoloration of the roof, which won't hurt
If the RVer understands that minute particles (dust) from the
membrane will flake off, and combined with water, make some
dirty-looking marks on the RV, which are easily washed off.
Rubber roofs are not cheap. They require care. If installed properly
and if maintained properly, they can be very nice and almost
leak-proof. The material, if properly applied and maintained will flex
just slightly with temperature and weather and may (should?) last the
life of the RV. However, any deviation from any of the above "ifs" can
be a real
"Hitcharama RV" in New Jersey uses a
product called "Reliable Cleaner" for all their coach preparations. It
contains Glycol-Butyl-Ether, Non-ionic Surfactants, Sodium
Metasilicate and is water based. Might be okay?
While lurking around the back room of a place that does rubber roofs,
look for fairly large scraps of the membrane. It makes excellent
gasket material for water pumps and sewage macerators. It's good for
covering sharp edges and inserting between things that rub together.
It maintains its flexibility and is good for use as a flap over
receptacles and leaky upper hinges on storage compartments.
Other Roof Coatings.
There are a number of paint-on/roll-on coatings available. Standard,
mobile home or RV roof coatings of this type are not suitable. All
they will do is flex, crack, peel and leak. You must use a coating
that is clearly labeled as being an "Elastomeric." Elastomeric simply
means it has a PTFE non-stick ingredient that allows it to stretch as
much as 40% without cracking loose.
Properly applied, in successive
coats, using one gallon per 10 feet of roof length, this stuff
prevents leaks and enormously improves insulation. The key is
"properly." First, you've got to properly seal everything up. Then you
have to scrape off the loose crud, globs of old asbestos coating,
flakes and such. Use a cleaner to remove mildew. Fortunately, you
don't have to remove all old coatings, just the shabby stuff. Good
elastomeric will cover a multitude of old sins.
Seams, cracks, edges of patches and
the like should be treated first. Building supply stores will have a
4-inch wide fiber mesh tape (usually yellow or black) made for this
purpose. If you use the "Liquiply" brand of elastomeric, they have a
matching caulk that comes in gallon cans and caulking-gun tubes. It's
the same as the coating, just thicker.
Spread a layer of this all along the
seam, for example about 6" wide. Embed a length of the tape in it with
fingers, putty knife or similar. Let it dry. Then spread another layer
over it and work it well into the tape. Touching up is easy. Just add
more after the previous layer dries. (If you keep spreading or
brushing this stuff too long, it starts to dry and gets hard to
handle.) If you're using the Kool Seal brand, you won't have matching
caulk, but the coating itself will do as well. You'll just need to
spread more layers because it's thinner.
Finally, coat the whole roof with
successive layers. You want a nice thick coat, but don't lay it on too
thick at one time or it'll take forever to dry. The base material for
elastomerics is a latex. If it gets rained on before it dries, you've
got a mess. The stuff can be sprayed on, but you'll get it all over
everything. Brushing works well. Some people use a paint roller for
even coats but it's hard to spread because it's so thick. One gallon
per 10 feet of roof length (don't deduct for A/Cs, vents, etc.) will
allow about three good coats, even if you use some for patching seams
Properly done, you won't have leaks
and in our test we measured (albeit unscientifically) a 20-degree
reduction in roof temperature during the summer. That's significant.
Is it condensation or a leak?
Is it a leak from outside or inside?
Frequently, people have damp bedrooms and bathrooms, often with a
musty odor. No big puddles, just damp and smelly. The first thing they
do is start running heaters and fans. Then they cover the walls, put
in storm windows and buy sacks of moisture-absorbing chemicals. What
they should have done first is check for leaks.
The toilet is often the culprit, but
not usually the sewer connection through the floor. If that's the
problem, it won't be just a bit smelly, it'll really be smelly.
The vacuum breaker and the toilet
inlet valve, if just slightly loose, will allow just a bit of water to
leak at each flush. This water is concealed by the cosmetic plastic
housing around the toilet. Little by little, it permeates the carpet.
It's complicated by the toilet being jammed in a corner or up against
the wall. Many RVers have never gotten down on hands and knees and
really examined what's going on down there.
Try poking a flashlight in behind the
toilet, then hold the pedal down for about three gallons worth. Feel
around with fingers.
Tub or Shower:
The tub or shower, especially if
mounted above the floor, is another likely place. Many are surrounded
by vinyl wall covering with joints "sealed" by moulding. Again, a
little bit of water, over a long period of time, finds its way down,
down, down until there's a permanent damp area. In many rigs, the
entire floor is carpeted during manufacture and everything is built on
top of it. Eventually, the whole place becomes a giant blotter.
On hands and knees, with a
flashlight, peer under cabinets, remove a few drawers, open outside
compartments, have someone turn on shower and spray around a bit. Look
for evidence of moisture on walls. Examine closely the connection
between trap and drain. Like windows and other openings, don't try to
squeeze a bead of tub sealer along all the seams; it'll just look
crummy and won't last. Remove suspect mouldings, reseal and replace.
Water lines can really fake you out,
especially where the city water fitting enters the RV. It's usually
halfway up the wall. If the leak is serious, there will be a big wet
spot somewhere. If it's a slight leak, the water may run along the
line for several feet and just slightly dampen lots of places (usually
behind cabinets, under beds and the like). Sometimes you can feel
around for this kind of leak. Just one wet drop on your finger means a
leak. Plumbers (good ones) don't rely on fingers, they use a wad of
toilet paper. Any moisture at all will show up.
Most RVs now use the gray, plastic
water line with "Qest" style fittings. These can be fine if installed
properly and not stressed. Connections are made with rings clamped on
with a special tool. RVers often try to fix these fittings, or add on
new ones, with standard hose clamps. This is the way to cause more, or
worse, leaks. If you have this kind of plumbing, it's to your
advantage to invest in the proper tool.
More Inside Leaks:
So far I haven't mentioned
condensation, just water that gets in from someplace and gives the
same effect. In most cases, this kind of thing is what people think is
condensation. Actual condensation is usually taken care of through
adequate ventilation. Your door, range hood vent, furnace, air
conditioner, window frames, and several other places all combine to
provide a lot of ventilation.
Even with good ventilation, there are
several in-house activities that can saturate the air with moisture.
It, in turn, condenses on walls and everywhere:
Washing clothes, dogs and similar,
and hanging things to dry in the bath.
Boiling lots of water for a long
time (like 6 qts for noodles) without using the range-hood vent fan.
If your fan, like most, is ineffective and noisy, get a good one. You
can get 12 VDC or 120 VAC "muffin" fans (as used to cool electronic
equipment) that are very quiet, use very little electricity and will
move up to 105 cfm (cubic feet per minute) of air for as little as $15
from electrical surplus places.
Running a water distiller in your
house is going to load the air with water. So will the endlessly
Catalytic heaters make water vapor.
As from any other source, it will condense on cool surfaces unless you
ventilate. Odd as it seems, slightly opening a ceiling vent can reduce
this moisture significantly without making the house cold. Another
point: catalytic heaters technically don't heat air, they radiate heat
directly to objects (and people). However, air is full of dust and
other particles which get heated. Running an ordinary fan, at low
speed, circulates this warmed air and actually makes the RV feel
warmer (unless the fan is pointed at you).
Circulating air, even in the winter
in a closed RV, can greatly assist in dissipating moisture. Note how
motor homes often use one or two small fans on the dash to remove
"fog" from windshields. The same fans, table fans on low, muffin fans
mounted on the ceiling and pointing along the length of the RV, can
all help. (And in some cases, solve the whole problem.)
Two people in a closed-tight RV,
along with panting pets wee-weeing in a cat tray, wet towels,
simmering coffee pot, convection/microwave (where do you think all
that steam goes?) etc., will pump a lot of water into the air. If you
don't get rid of it, you'll have condensation problems (and the place
Building Better RVs:
Building better RVs is not a
suggestion, it's already being done. In some cases this results in odd
problems. I examined one new, lightweight, super tight RV that
apparently had such extreme condensation up inside the ceiling that
water was dripping from seams. Lowering a bit of the paneling we found
Condensation? No. It just seemed so.
A slight leak in the roof allowed water in. The inner ceiling had been
built so tightly/well that it didn't just run on through as usual.
But, in that closed, warm space, it just kept turning to vapor until
the whole thing was loaded with water. Finding and fixing the leak was
a problem. Drying the inside out was an enormous problem. The main
point, though, is that condensation didn't cause the problem; it was
Refrigerators don't usually
contribute to general RV condensation, but they can. If the reefer is
soaking wet inside, it might be working too hard and/or have a loose
fitting at the door gasket. Fix it. If it's wet enough inside, the
water will run out the bottom and ruin your paneling, carpet, and
contribute to interior moisture. That's not condensation; that's a
More often, excess water is due to
"dumb" stuff. Most reefers have a tray under the inside fins to
collect water (and most are now self defrosting, so they make water
quite often). A hose is connected to the tray and lets water go
through the back of the fridge where it collects in a cup and
Frequently, people don't properly
connect the inside hose to tray and water just runs down inside the
reefer. Also, people might connect the hose but don't fully insert the
tray into the exact position under the fins (often because they put a
huge hose clamp on the hose and the tray will no longer go where it's
In either case, there can be lots of
inside water. Instead of checking for the obvious, they go out and
spend money on battery operated air circulating fans and other forms
Unless it's way too hot outside, the
RV reefer should not make so much water that it overflows the
evaporator cup or runs down inside the fridge. Nor should you require
added air circulation inside the thing or up the back of it UNLESS you
have a faulty unit, loose gaskets, have overloaded it with stuff, or
keep opening the door for ice cubes. Similarly, if your cup keepeth
running over, you might want to run the hose outside the rig (old RV
tip), but you shouldn't do so without also determining the actual
cause for so much water.
If you haven't a leak, haven't
carelessly been making your own condensation, and have ventilated the
RV properly, you shouldn't have any condensation problems. But you
Some RVs are constructed so cheaply,
with so little insulation, that outside temps collide, if you will,
with inside temps. If it happens on the outer wall, you get moisture
and rot inside the walls. Inside, and you get sweaty walls. As a worst
case, you get both. The simplest fix is to get rid of the thing. (Next
time, become a member of the RV Consumer Group before buying an RV so
you'll be warned of faulty rigs in advance.)
Some people choose to reinsulate.
It's a job, removing paneling, but can be done. You don't need to
remove the paneling completely in some cases, but can get it far
enough away from the wall to allow slipping in 3/4 inch pieces of
urethane foam. Not a lot of fun, but some of us have done it when we
didn't want to or couldn't afford to get rid of the RV.
Often, a second wall covering will do
the job. Sometimes carpet works. I had one rear room, with minimal
heat, and the walls always felt cool and damp. After carpet covering
they didn't. A front room was well heated and at times very damp.
Carpet with a 1/4 inch foam backing took care of it. However, you need
to experiment first before going through the carpet installation,
because you might just be covering up dampness that's still there,
doing its dirty work behind the carpet. Scrap carpet, temporarily
attached, can give you a clue. (See more below.)
There are some very high quality
vinyl wall coverings available. Not just wallpaper, but thick vinyl.
In all cases, the added coverings give better insulation. And they
certainly look a lot better than the cheezy paneling that comes with
the RV. (Carpeted walls make it easy to hang things also. When you
move them, you just rub the carpet and the mark's gone.) Some people
cover walls with cork. Works well, but you get an incredible amount of
dirt off it without a protective spray coating.
Metal Frame RVs:
Some of the so-called "better" RVs
have metal frames. If the siding and paneling were attached properly
(over a thin foam-core or similar barrier), you shouldn't have a
condensation problem anyway. If not, the metal frame makes a "bridge"
right through the wall and you'll see wet or damp areas. These
"bridges" often take the form of vertical and/or horizontal "lines" of
cold, damp about 1-1/2" wide (indicating that the metal structure
inside the wall is up against the paneling with no moisture barrier).
Sometimes, wall coverings, as mentioned earlier, work. A test is to
get a roll of the foam-and-aluminum-foil tape with a slightly tacky
backing that is sold to wrap pipes for insulation. If you're lucky,
you can tape a few pieces to the wall to see if a covering works.
Remove tape without peeling the cheap paper "wood grain" and trade the
rig in if it doesn't.
Metal Window and Door Frames:
These can be real "sweaters." Some of
the most expensive RVs have compression-type frames where the outer
and inner window, for example, are squeezed together with screws (and
aren't really attached to the RV siding at all). The result is an
instant bridge and moisture. Storm windows generally work, but who
wants to haul around all that junk? Some people have had good luck
with removing the inside frame and covering its inner surfaces with
glued-on or sprayed-on vinyl or foam. Others have succeeded in just
putting up good draperies (but not often). Some have had success with
the wood slat and woven yarn window coverings. Some have "outlined"
windows with a wood frame of 1 x 2 inch and fitted the above or
pleated shades inside them. Very nice and, if done with care, like an
overlapping edge of lath to go around the ends/bottom/top of the
shade, can provide a total window cover. You'll be amazed how this
kind of window cover can save heat in winter and cool in summer. Some
of us have built things like Japanese-style shoji screens (with
plastic, not paper) over the windows. The point is: Get imaginative.
Doors? Hang a drape on a swinging rod
inside the actual door. It reduces condensation in cold weather.
Remove in warm or leave it and have an extra fly barrier. (Also
prevents visitors from standing there with their nose up against the
Heaters and Dehumidifiers:
Failing all the above there are, of
course, heaters and dehumidifiers. Unfortunately, all are electric,
heat-producing devices. Most are only available in 120 VA. If you've
trudged through all this and corrected all the deficiencies, you
shouldn't need them unless you're parked in a humid swamp. Some
samples available in most boating, and many RV, stores are:
Thermo-electric heaters, 8 watts to 25 watts of safe warmth to eat
dampness. There are several crystal-filled bags/jars of stuff
available that soak up moisture.
Definitely not recommended are simple
light bulbs. Dangerous! Especially when used in closets.
DRY ROT (Called Serpula Lacrymans
-- more accurately should be called wet rot.)
You won't find any technical
references that I know of. Most repair shops won't even attempt these
repairs except at great (prohibitive) cost. It can cost more than the
RV is worth. Still, sometimes, for various reasons, people do
successfully rebuild such a mess.
Just a few tips before you get started:
Don't start taking things apart until you know where the water leaks
are coming from!
To do this effectively, you need to "overpressurize" the interior of
the RV. It's simple, but can take some time. You will seek to have
more air pressure inside, than outside. Simply tape up vacant "holes,
cracks or other openings" and/or stuff them with what's at hand. Then,
run a line from an air compressor or (vacuum cleaner backside) into
the RV. It's not critical that everything be totally "tight."
A more efficient (quicker) way to do the above leak check is to rent
one of the fans used to inflate portable structures. It has a BIG fan
and feeds the air through a very large flexible hose. You can stick
the hose end in a window and plug the excess space with tape,
cardboard, rags, etc., as above.
Before doing the leak check, you'll need to open some of the inner
ceiling so the air can pressurize the roof. Easier way is to remove
trim from ceiling vents and (gently) pry inner ceiling loose and
insert wedges, pencils, whatever to keep it open.
Once the air pressure on the inside is more than the air pressure on
the outside, you go around the whole RV (sometimes on a ladder) and
spray a windex-type bottle, with a mix of detergent and water, on any
possible "leaker" place (like you would when looking for an LP gas
leak). Seams, joints, whatever. If bubbles appear, that's where air is
leaking out -- and that's also where water is leaking IN. (This is
basic high-school physics.) Mark these places.
Your next job is to fix those leaks! If you don't do this first, and
if you don't do it properly, leaks (and more dry rot) will keep coming
back to haunt you in the future. (Fixing leaks is covered in earlier
Aluminum extrusions: These are little more than cosmetic crap
that conceals the crummy way an RV is assembled. Before you actually
fix the leaks, you'll need to remove a lot of the extruded aluminum
trim pieces. Do it carefully, so you can reuse them. Peel off the
cheezy, smeared caulking and putty tape sealer (aka monkey poop) and
examine the seams for leak evidence (per your marked bubble areas from
earlier). If you then remove the staples/nails holding the siding in
place at the edges, you'll be able to "gently" pry the edges loose to
a surprising degree (putty knives, slim wedges, etc.). This allows
poking around to see what you really have/don't have in there.
While you're doing all this, it's
obvious you need the RV under a shelter or have a large tarp you can
batten down during inclement weather. As you go through this drill,
the interior framing should start to dry. While that's happening, you
should still be inspecting and examining.
Don't just initially tear out
anything that appears rotted. Some dry-rotted wood can be "rescued" --
at least to some extent. The product I use is called "Git Rot" and is
available at good marine stores or from "West Marine" (www.westmarine.com)
or (800)-boating. I recommend you call West Marine and get their
"master catalog." There's a whole bunch of products in there that most
RVers don't know about. "Git Rot" is a two-part mix (like an epoxy,
but thinner). Much dry-rot can be saturated with this. It creeps
through the wood and does a "molecular thing" with the cellulose
that's left. If properly done, the remaining wood is like an epoxy and
can be cut, drilled, etc. Added pieces of wood can be affixed to it
and you can, if careful (lucky) end up with a rather stout structure.
Git Rot is tricky to use. Carefully follow the detailed instructions!
West Marine has a few other similar products as well. Another favorite
dry-rot product is "Poly All" at
Once you open up the outer shell, and
locate the rot, then, before you start using Git Rot (or similar), you
need to open up the inner shell (at appropriate places) as well. Cut
away the thin paneling on the inner RV. Save the pieces for patterns
when replacing. Once removed, you will REALLY see the rot that
might be in there -- and be able to repair it.
Ref: Fiberglass outer skin.
If you do the job right, you should be able to save the outer
fiberglass skin (because it's hard to find). If you're lucky, you'll
have a preformed end cap. The entire end cap can be removed to get to
the structure (not hard, just laborious). You'd want to "beef" the cap
up anyway and removing it makes getting to the structure easier. If
you've just got fiberglass siding butted together at the corners, try
to save it. Finding fiberglass that matches your RV's style will be
difficult. First, try the RV manufacturer. Also try calling local RV
shops and ask where the damaged "junkers" go. Check "yellow pages" for
fiberglass distributors (who can refer you to retail sources). You
might call "Wabash National Parts" (800) 621-7949 for a clue. Also
check www.all-rite.com/fiberglasssiding.html for what they have
First, fix the leaks.
Then reduce the water you make on your own.
Then insulate the thing properly.
And, then, you shouldn't need extras.
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