Again we are concerned with trailer leaks and proper caulking maintenance. This is a common complaint and will eventually effect any trailer owner as the trailer ages. Some owners have been told that their caulking will last a decade and not to worry. Unfortunately this is an improper and simplistic answer. There are many reasons why this is not true.

Ten years of leak free ownership, cannot be held to a standard. There are many types of caulking, many different brands and varying qualities. Because manufacturers are constantly involved in cost cutting measures, it's difficult to discern what they are presently using in their constructions.

Another consideration is the environment in which you live. A hot AZ sun will bake many caulks into a hardened worthless string. A trailer that is used close to any coast line, will have salt corrosion trying to underpin the sealant. A trailer used in the Northern states will be frozen for lengths of time, heated, wetted and refrozen. In my area, we have that plus a great deal of road salt.

How the trailer is used, will effect the caulkings' life span. Travel off a main road on unimproved trails, and the trailer will be subjected to a great deal of stress and twisting. This is tough on the manufactured joints and will quickly weaken any caulking that has lost its elasticity.

The materials used in the trailers' construction, will effect the longevity of the caulking. An aluminum trailer with a fiberglass roof, or any construction whilst materials are mixed, will result in varying expansions and contractions of the different materials. The colour of the trailer will have some affect, with bare and dark painted aluminum heating up greatly on a hot day, expanding and contracting more that a lightly coloured model.

A visual inspection will alert you to possible caulking failures. If you push your fingernail into the material and it flexes, chances are that it's still good. If it's hard and brittle and pieces break off, it's shot and need to be replaced whether it's leaking or not. Look for obvious cracks and missing pieces. Do not apply new caulking over the old, remove the old first.

Purchase and use the best caulking materials you can afford. Your time is valuable, and by using quality products, you will lessen the chances of having any future leaks for sometime.

Here's a copy of a previous article I wrote about why trailers leak:

Subject : WHY DO TRAILERS LEAK? Posted : 2008-01-21 1:17 PM Post #74948

A better question should be; "why don't trailers leak?"

Most horse trailers are built with formed aluminum sheets fastened over a supporting structure. The aluminum is water proof, it doesn't leak. It is used in the construction of automobiles, airplanes, space shuttles, boats, soft drink cans, even the compressed air cylinders in my scuba gear. It is strong; it can be continuously stretched, compressed, bent, heated and cooled and it still will maintain its strength.

When it is installed on the roof of your trailer, it is bright, shiny and pristine. The only seams are on the trailer sides and ends where the flat roof transitions into the vertical sidewalls. This is done by cutting, bending and welding, or attaching formed pieces to it. If turned upside down, it could very well be the hull of a boat,...... and not leak a drop.

Now the problems start. It doesn't leak, so it also doesn't have ventilation. We need to have vents for ourselves and the horses. We need a large one, so lets cut a hole about 14"  square right in the middle of the roof. Each horse needs one, lets cut three more holes in the aluminum. Attached to these holes are the vents we want to install; the large one has an equally large flange that is drilled to allow screws to hold the vent to the roof. Lets say there are a dozen screws that hold things together, we now have to drill a dozen holes in our not so pristine piece of metal. Each horse vent will require maybe six or eight more screws and an equal number of holes. How many holes are there now in the metal? Are you counting?

Now, we aren't simple inhabitants, and our demands exceed those of just a vented interior. We want a refrigerator, toilet and shower, and an air conditioner; we want to be as comfortable at a campsite as we are at home. An air conditioner requires another hole about 14" square, and it is secured in place by another dozen screws; the refrigerator is gas and another hole and vent cover is needed. Want a toilet? We need a stack vent for the waste water tank, and the same if we have a sink. Want a TV antenna? Solar charger? Start to get the idea?

What happened to our perfect piece of aluminum? It now looks like a piece of Swiss cheese and has had many dozens of screw holes drilled into it. A young person is sitting on the roof with a power tool, various vents, a caulking gun and a large box of screws. It is his job to apply a bead of sealant around the holes, adjust the various flanges to their correct positions, and drill and fasten them to the roof.

The tube of caulking empties just before he completed his circling of caulk around the hole. It's just before his break time, so he smears the caulk around to fill the gap, puts the vent on and leaves. Another worker, using his power tool, over tightens one of the flange screws. The plastic flange cracks with an almost indeterminable line that is difficult to see.

The beautiful new trailer is now going 70 mph down the road to the dealer. A truck passes him going the other way at a similar speed. All of the non- aerodynamic vents that are fastened to the roof, were just hit with a combined wind speed that equaled the most dangerous of hurricanes. How many more times did this occur in just this one trip? Can you imagine the stresses that are placed on those components?

It's starting to rain now, and at 70 mph the rain is being forced into the smallest of cracks. Remember the plastic flange that is cracked?

The trailer is sitting at the dealer. It is baking in the hot sun, and the metal has expanded significantly. That evening it is very cold, and the metal shrinks, pulling itself into a smaller section. This will happen at every temperature change.

The trailer, now being enjoyed by its new owners, has a full load of horses and tack and is on its way to a trail ride in the mountains. It's off the road now, going up a twisting and bumpy road that resembles a cow path. The trailer is creaking and groaning as its body is being twisted by the uneven ground. The stresses on the front hitch are significant, while the frame is being pulled from the tons of tension from the tires. It would be as if a giant pair of hands were trying to twist and pull the trailer apart.

The trailer has survived several years of torture. It has been baked, frozen, pulled, and tortured in many ways. The caulking, installed by the young workers has long ago dried out and is no longer flexible. One more time, the metal contracts and this time the caulking cannot maintain the gap; it fails and pulls apart. The rain comes, and the small gap in the caulking, maybe as narrow as a paper thickness, allows the water to enter. At first it isn't noticeable, but over time the caulking continues to deteriorate, and the leak gets larger until it is apparent.

The whole crux of this tale is to show that the aluminum roofs don't leak. The joints where the roof and the holes meet are the source of problems. It all depends on the integrity of the caulking used to seal the  joint. If it is improperly applied or old and worn out, you will have a leak... REGARDLESS OF THE TRAILER BRAND. Your trailer has endured a great deal of punishment, while only demanding a minimal amount of maintenance. Your multiple thousand dollar trailer is dependent on $20 worth of caulking to remain water tight.

Whether there is a gap of caulking missing during manufacture or a worn out strip many years later, 99% of leaks can be attributed to caulking problems.

BOL  Gard