Seams, Sealants and Seals ...maintenance of your motorhome seams and seals

Seams, Seals and Sealants

Originally shared in 2007 by James Jordan, formerly Service Technical Resources Manager, at the now defunct Country Coach, LLC

Seams, Seals and Sealants: Careful inspection and maintenance of these three S’s will keep the interior of your coach dry and weather tight. Here we address the “when, where, and what” of the subject. Seams & joints have some sort of sealant or adhesive applied during the coach build process ensuring a good fit and sealing any voids or gaps. Movable parts (slide outs, entry doors and storage access compartments) have rubber or vinyl seals for weather- and air tight fit.

Careful Inspection is Important: During normal operation your coach is subjected to extreme conditions and stress. Over time this will result in failure of seals and sealants. Sealants don’t last forever. Age, thermal cycling, UV exposure (and certain sections of I-10 and I-40) cause sealants to degrade and allow water or air to infiltrate. A regular inspection catches these problems before they become major.

How you use and store your coach will affect how often you should do this inspection. A coach stored indoors in a temperature controlled environment will probably need inspected once a year. Aging is the primary concern so after the coach is several years old you may wish to inspect more often than annually. Coaches in extreme climates w/UV exposure should be checked every 6 months; a coach outdoors in the southern regions (like Arizona) every 3-4 months.

The average owner can inspect most of the areas of seals. The roof may not be one of those areas. Climbing a 12-14 foot ladder and crawling around on hands and knees on the coach roof may be something left to service center techs. Take the coach to a shop for inspection of the top exterior wall seam of a slide out room with a retractable awning attached. These awnings need removed to access the seam. Removal procedure can be hazardous. Spring-loaded retractors store tremendous kinetic energy if not handled properly may cause bodily harm and expensive coach damage. Stick to inspecting areas from the ground.

Look for sealants in any area where two or more surfaces come together to form a joint or seal. The roof has many such areas: sky lights, air vents, plumbing vents, antennas, refer vents, front / rear caps and air horns. Window sealant treatment will vary with coach/make/year. On some models sealant is a caulked bead on the exterior, on others, compressed foam product sandwiched between window frame and sidewall. Slide-outs have several seams. Don’t forget to look at inside corners of slide room openings in the coach sidewall. The beltline or raised cap running horizontally along coach is a candidate for inspection. Also the coach underside, as well as topside.

Signs that repair or replacement is required: Look for obvious signs the sealant has lost adhesion and fallen out, or is loose and partially detached. Next take a close look for discoloration, cracking, shrinking or voids. Some discoloration is normal and consistent with UV exposure. Press the sealant with your finger nail to test for resilience or hardening. You’ll know what’s abnormal as compared to other areas with similar function, sealant and UV exposure. Pay attention to items added to your coach aftermarket. Improperly sealed roof penetrations as a result of post manufacture additions are not uncommon.

Moving on from the sealants to the seals around slide rooms and doors…There are typically two sets of seals on each slide out room. One on the exterior of the coach wall that seals the room when retracted, and one on the interior that seals the room when extended. Both are similarly constructed and known as “bulb” or “D” seals. The primary difference between the two sets is that the exterior seal system incorporates a short flap known as the “wiper.” The wiper clears water off of the slide as it is retraced. If you notice the wiper is oriented outwards in one area and inwards in another, this is normal and does not prevent it from performing its task-wiping water. Inspect the bulb seals for cracking, hardening and loss of resilience due to UV exposure and age. Be alert for any tearing or voids in the corners. Is there wind noise you hadn’t noticed before? Give the entry door seals a close inspection. Entry door bulb seals should be inspected for the same conditions as slide out room seals. Pay attention to the front or leading edge seal where it is prone to extra wear and use.

Bulb seal maintenance: Keep the bulb seals clean and free of debris. Look for twigs, leaves, etc. Use a mild detergent solution to wash seals. Baby powder is good for lubrication. Inexpensive and a preferred treatment, just wait until the seals are dry and apply enough to get a good coating. Products such as 303 Aerospace Protectant or pure silicon are acceptable but often more difficult to locate, and more costly than baby powder. DO NOT use any product containing petroleum distillates, as this may lead to premature failure of seals and will attract dirt.

Sealants typically do not require any maintenance, but do require periodic repair or removal and replacement.  Keep your coach in top operating condition and the interior dry with periodic inspections of seams, sealants and seals to keep you on the road and out of the repair shop.

BE WATCHING FOR MORE ON THIS SUBJECT SPECIFICALLY WHICH CAULK, SEALANT ETC TO USE...COMING IN A FUTURE POST.