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Camper Roof Sealing: The Essential Guide to Stopping and Preventing Leaks (2024)

Camper roof seals prevent your roof from leaking and are an essential part of the construction and maintenance of your RV. A plastic or aluminum RV roof, as well as the seals around fixtures, develop leaks over time due to natural wear and tear. Choosing the right sealant type and applying and maintaining it correctly ensures the roof of your camper is healthy and watertight. This article explains the need for a properly sealed roof, details the different types of sealants, and goes over the application process for each.

 

Shane has been teaching people to convert campervans for years; he's the author of Roaming Home; The Comprehensive Guide for Converting Your Van Into a Campervan, writer of The Van Conversion Newsletter, instructor of The Van Conversion Course over at Udemy, and a full-time vanlifer for 4 years!


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TL;DR: Our Camper Roof Seal Top Picks

We discuss many sealant types in detail in this article. The products we recommend for each type are:


Recommended Non-sag Sealants

Sikaflex-521UV
Sikaflex-221
Sikaflex-291

Sikaflex is a trusted brand whose non-sag sealants are industry standards. These sealants are perfect for sealing the joints between your roof and fixtures such as air-con units, vents, and antennas.


Recommended Self-leveling Sealants

Dicor self-leveling lap sealant

Pro flex RV





















Dicor and Geocel both make well-regarded self-leveling sealants with RV applications in mind. Self-leveling sealants spread out as they cure, making them especially good for ensuring a uniform seal over large areas.


Recommended Sealant Tapes

Eternabond







Eternabond and Dicor both make industry-standard sealant tapes. Sealant tapes are strong, flexible, and waterproof, and are especially well-suited for long, straight lines.


Recommended Sealant Coatings

Kool seal elastomeric roof sealant
Marlin coatings silicone roof sealant
Liquid rubber RV roof coating


Sealant coatings are applied to the whole of an RV or caravan roof and provide an essential extra layer of protection. Different coating types are appropriate for different roof materials and environmental factors. The three we recommend here are all well-regarded examples of their respective coating types.


Why Do Camper Roofs Leak?

RV roofs leak because of the breakdown of the roof and sealant materials over time. The roof of a converted camper whose base is a panel van is less prone to leaks, as it's part of the same sturdy metal body as the rest of the van. However, leaks can still occur wherever the roof has had a hole cut in it. Vents and skylights, air con units, chimneys, and other such fixtures are installed through a hole cut in the roof. The sealant that you used to seal this hole around the fixture can degrade over time, due to exposure to sunlight, weather, vibration, and extremes of temperature.


Unlike converted campers, RV roofs are made of separate pieces of aluminum, rubber, plastic, or fiberglass. These roofs degrade over time in the same way as sealants on converted campervan roofs. Physical wear and tear from hail, falling debris like tree branches, and walking on the roof all add to this degradation. Common leak points on an RV roof include the edges where the roof is bonded to the rest of the vehicle, seams between panels of roof material, joints around fixtures, and areas where water pools.


Whether you've got a converted camper whose roof is part of the bodywork, or an RV with a roof panel made of different material, damage is exacerbated by insufficient cleaning and lack of maintenance. A properly applied and maintained sealant is essential for preventing leaks in the roof of your RV.


Understanding Camper Roof Seals

Camper roof seals come in different kinds and are used for different applications.


Non-sag Sealants

A non-sag sealant is a polymer-based sealant that comes in a tube and is applied using a sealant gun. These sealants hold their shape as they dry, and are often strong adhesives as well. Sikaflex is a popular brand of non-sag sealant and an industry standard. There are many kinds of Sikaflex: Sikaflex-221 is a versatile sealant that seals and bonds, and resists vibration and general degradation; Sikaflex-521UV is a campervan-specific variant and comes with added resistance to UV degradation; and Sikaflex-291 is similar to 221 but cures much more quickly and is thus best used for quick repairs. Non-sag sealants are used to seal the joint between a fixture (air-con units, vents) and the roof or to seal seams in the roof material.


Self-leveling Sealants

An RV roof self-leveling sealant is applied in the same way as a non-sag sealant and is also used to seal the joints between fixtures and your roof or seams in the roof material. The difference is that a self-leveling sealant spreads out as it cures, infiltrating nooks and crannies and forming a very low-profile seal. Self-leveling sealants such as those made by Dicor and Geocel are a good choice for large, horizontal surfaces and complex shapes where it might be hard to get a perfect seal using a non-sag sealant.


Sealant Tapes

RV roof seal tapes are elastic, waterproof tapes that are also used for sealing joints and seams. There are different kinds, and you may hear these referred to as butyl or mastic tapes. These tapes, like those made by Eternabond and Dicor are best for simple shapes and long straight lines. Camper roof sealing tape is very simple to apply and has no curing time, as well as being easy to inspect and replace. Eternabond and butyl tapes are durable, flexible, and waterproof, and are considered permanent sealants, though they may not last as long as polymer-based sealants. Their advantage comes from their ease of application and replacement. Mastic tape, whilst perfect for use at home, isn't as strongly recommended for RV use as it's not as durable as either Eternabond or butyl tape.


Sealant Coatings

Sealant coatings are applied over the entire roof surface, rather than to seams in the roof. Their purpose is to enhance the durability and UV resistance of the roof as a whole and form an important extra layer of protection. Sealant coatings are not necessary on an all-metal converted campervan roof. A new application of sealant coating rejuvenates an aging roof, filling in small cracks and pinholes that would otherwise grow over time. It will also enhance the durability of your roof, protecting against degradation from weather, temperature extremes, debris, and harsh sunlight.


There are a few different kinds of sealant coating, and each is suited to a particular roof material and use case. Silicone coatings, like Marlin's Silicone Roof Sealant, are UV-resistant and durable, with added flexibility compared to acrylic coatings. Polyurethane coatings, like Liquid Rubber's RV Roof Coating, are especially tough but are less UV-resistant than silicone coatings. Finally, elastomeric coatings, like Kool Seal's 2-part base coat and finish coat, are even more flexible than silicone coatings and expand and contract with your roof as it goes through temperature extremes. The kind of sealant coating you choose will depend on your use case and the material of your RV's roof (more on this below).


Choosing the Right Sealant for Your RV Roof

Whether you have a converted camper or an RV, you will always need an edge sealant for seams and joints. The choice between a non-sag edge sealant like Sikaflex and a self-leveling sealant is largely down to personal preference. Non-sag sealants might edge out self-leveling sealants for fixtures due to their dual nature as adhesives as well as sealants. They're also more flexible and vibration-resistant than self-leveling sealants.


An application where self-leveling sealants are worth considering is very large seals around large fixtures or where two pieces of roof material meet. When sealing such a large area with Sikaflex, it's more likely that you won't be perfectly consistent in your application, resulting in a seal that isn't uniform. An imperfectly uniform seal is more prone to developing leaks due to thinner areas wearing through faster. A self-leveling sealant flows horizontally as it cures, meaning the seal will be entirely uniform no matter the size. It's important to be aware, however, that the reduced flexibility of a self-leveling sealant might lead to cracking and necessitate more regular reapplication than a non-sag seal.


RV roof seal tape is generally not as durable as either non-sag or self-leveling sealants and is instead preferred because of how easy it is to apply and replace. It's well suited to long, straight lines, and is also very handy for quick repairs.


What About RV Roof Coatings?

An RV or caravan roof needs a well-maintained sealant coat to be fully protected against leaks. The choice here largely depends on your roof material and the environmental conditions your RV will be exposed to. Metal roofs expand and contract with temperature changes more than plastic roofs, and absorb more heat. Hence, these roofs can benefit from highly flexible coatings with a reflective component, like elastomerics. EPDM (rubber) roofs need coatings that are specifically compatible with the roof material. TPO and fiberglass roofs are more susceptible to UV degradation, and so benefit from acrylic and silicone coatings which offer enhanced UV protection. Silicone coatings in particular are very durable and are a good choice for RVs exposed to hail, heavy rain, and snow, or which are parked under trees.


Step-by-Step Guide: How to Seal an RV Roof

Here we'll give step-by-step guides for applying each kind of camper roof seal we've discussed. These guides are general and may not exactly match your use case, but will give you a good idea of the process and materials. If you're applying or renweing a seal around a roof vent or an air con unit, we have detailed articles on both of these subjects, including the sealing process. Check out our roof vent article here and our air con article here.


How to Apply a Non-sag Sealant

Materials Needed:

  • Polyurethane sealant (e.g. Sikaflex)

  • Caulking gun

  • Utility knife or scissors

  • Masking tape

  • Cleaning supplies (rags, isopropyl alcohol)

  • Protective gloves

  • Ladder or stable platform


Step-by-Step Guide:

  • Preparation:

    1. Wear protective gloves to avoid direct contact with the sealant.

    2. Clean both surfaces where you'll be applying the sealant, making sure they're dry and free of dust, dirt, oil, and old sealant. Use isopropyl alcohol and a clean rag to clean the surfaces. Isopropyl alcohol also dissolves polyurethane sealant and is useful to have on hand to clean any accidental mess you might get on your clothes or parts of your RV where you don’t want it.

    3. Make sure the weather is suitable for application. Avoid applying sealant in wet or extremely cold conditions as it may affect adhesion and curing.

  • Masking (Optional but Recommended):

    1. Use masking tape to outline the area where you will apply the sealant. This helps to create clean lines and makes cleanup easier.

  • Applying sealant:

    1. Cut the tip of the sealant tube nozzle at a 45-degree angle to your desired bead size. Puncture the seal inside the nozzle if necessary.

    2. Insert the sealant tube into the caulking gun.

    3. Apply a continuous bead of sealant around the base of your fixture. Ensure the bead is even and covers all gaps between the fixture and the roof.

    4. Smooth the bead of sealant using a gloved finger, a smoothing tool, or a caulking spatula. This helps to ensure good adhesion and a uniform seal. Wetting the smoothing tool or your finger with a little soapy water can help achieve a smoother finish.

  • Inspection and Clean-Up:

    1. Inspect the seal to ensure it is uniform and has adhered well to both the roof and the base of the fixture.

    2. Remove the masking tape carefully before the sealant fully cures to ensure clean edges.

    3. Clean any excess or spilled sealant with a rag and isopropyl alcohol before it cures.

  • Curing:

    1. Allow the sealant to cure according to the manufacturer’s instructions. This usually takes about 24 hours for initial curing, but full curing may take several days. Avoid exposing the sealant to water during this time. Fast-curing varieties will take less time to cure  —  check the instructions on the tube


How to Apply a Self-leveling Sealant

The process of applying a self-leveling sealant is essentially the same as for applying a non-sag sealant. They both come in tubes and are applied using a sealant gun. The difference is that a self-leveling sealant spreads out horizontally and levels itself as it cures. This means that you don't need to smooth out the sealant yourself. However, you do need to make sure that you apply enough sealant to cover the whole area you want to seal. Checking the seal means ensuring that the sealant has flowed into all necessary gaps and has formed a complete seal. Finally, it's particularly important that the sealant isn't disturbed and doesn't get wet during the whole curing period specified on the tube. You might like to ensure this by covering the sealed area with a tarp until it's completely cured.


How to Apply Sealant Tape

Materials Needed:

  • Sealant tape (e.g., EternaBond)

  • Scissors or utility knife

  • Cleaning supplies (rags, isopropyl alcohol)

  • Roller or squeegee (for pressing the tape down)


Step-by-Step Guide:

  • Preparation:

    1. Clean both surfaces which will be sealed by the sealant tape, making sure they're clean, dry, and free of dust, dirt, oil, and old tape. Use isopropyl alcohol and a clean rag to clean the surfaces. Proper cleaning is essential for good adhesion.

    2. Make sure the weather is dry and the temperature is suitable for application, typically above 40°F (4°C).

  • Measure and Cut the Tape:

    1. Measure the length of sealant tape you will need to go around the base of the fixture or along the seam. Add a little extra length to ensure complete coverage.

    2. Cut the sealant tape to the required length using scissors or a utility knife.

  • Position the Tape:

    1. Remove a small portion of the backing from one end of the tape.

    2. Carefully position the tape starting at one corner of the fixture or one end of the seam. Align the tape so that it will cover the seam.

  • Apply the Tape:

    1. Gradually remove the backing as you press the tape down along the perimeter of the fixture or seam. Make sure to press firmly to ensure good adhesion and avoid air bubbles or wrinkles. Don’t stretch the tape as you apply it, as this can create weak spots.

    2. Continue pressing the tape down until you have completely encircled the base of the fixture or covered the whole length of the seam.

    3. When you reach the starting point or end of the seam, overlap the tape by at least one inch (2.5 cm) to ensure a watertight seal.

    4. Press the overlapping section firmly to ensure it adheres well.

  • Press and Secure the Tape:

    1. Use a roller or squeegee to firmly press the tape down along its entire length. This helps to ensure good adhesion and a tight seal, particularly at the edges and any overlaps.

    2. Pay special attention to pressing down the edges of the tape to prevent lifting.

  • Inspection:

    1. Inspect the sealed area to ensure there are no gaps, bubbles, or loose edges. If you find any, press down again with the roller or add additional tape as needed.

How to Apply a Coat Sealant

Materials Needed:

  • Roof coating sealant

  • Roof cleaner (e.g. Beest USA's RV Roof Cleaner)

  • Cleaning supplies (soft bristle brush, hose, rags)

  • Protective gloves and safety glasses

  • Painter’s tape

  • Paint roller with an extension pole

  • Paintbrush (for edges and hard-to-reach areas)

  • Ladder or stable platform

  • Stir stick or drill with a mixing attachment


Step-by-Step Guide:

  • Preparation:

    1. Wear protective gloves and safety glasses to protect yourself from chemicals and debris.

    2. Ensure the weather is dry and the temperature is suitable for application, usually between 50°F to 90°F (10°C to 32°C). Choose a day with no rain expected for at least 24 hours.

  • Clean the Roof:

    1. Clear any loose debris from the roof, such as leaves, dirt, and branches.

    2. Wash the roof with a roof cleaner or mild detergent (EPDM (rubber) roofs will need a special cleaner e.g. Dicor's Rubber Roof Cleaner). Apply the cleaner with a soft bristle brush, scrubbing to remove dirt, mold, mildew, and old sealant residues.

    3. Rinse the roof thoroughly with a hose, ensuring all cleaning solution and debris is washed away.

    4. Allow the roof to dry completely before proceeding to the next step.

  • Tape Off Sensitive Areas:

    1. Use painter’s tape to mask off areas you do not want to coat, such as vents, AC units, skylights, and edges. This will help create clean lines and prevent accidental coating of these fixtures.

  • Inspect and Repair:

    1. Inspect the roof for any significant damage, cracks, or areas that need repair. Address these issues before applying the coating.

    2. Patch repairs using a compatible sealant or patch kit. Allow the repairs to cure as per the manufacturer’s instructions.

  • Mix the Coating:

    1. Stir the roof coating thoroughly with a stir stick or use a drill with a mixing attachment to ensure the coating is evenly mixed. Follow the manufacturer’s instructions for mixing.

  • Apply the Coating:

    1. Start by applying the coating to the edges and corners of the roof using a paintbrush. This ensures these areas are well-covered and helps to create a border for the roller application.

    2. Use a paint roller with an extension pole to apply the coating evenly across the roof. Work in small sections, starting at one end of the roof and working your way to the other end.

    3. Overlap each stroke slightly to ensure even coverage and avoid missed spots.

    4. You may need to apply multiple coats, depending on the product instructions. Allow each coat to dry completely before applying the next one. This usually takes a few hours, but refer to the product's instructions for specific drying times.

  • Drying and Curing:

    1. Allow the final coat to dry completely. Curing times can vary, but generally, the coating should be left to cure for 24 to 48 hours without exposure to water or heavy dew.

  • Remove Tape and Inspect:

    1. Carefully remove the painter’s tape from around the masked-off areas.

    2. Inspect the roof to ensure the coating is even and there are no missed spots or thin areas. Touch up as necessary.


What About Windows?

Windows are another common campervan installation which require proper sealing. For window installations, the use of a window bonding kit is preferred. This is a kit containing a very strong bonding agent which also serves as a sealant. The bonding agent adheres the window to the side of your camper, meaning you don't need to screw or bolt the window in place.


As with all sealing, it's very important to ensure a uniform application of the bonding agent with no gaps. This means also being assiduous in your application of the glass activator and primer, which together enhance the strength of the bonding agent. Our comprehensive guide on window installation goes into much more depth on the subject of installing windows in your campervan.


There's a good case to be made for using another sealant around the very edges of the window to reinforce the seal. Either a non-sag sealant like Sikaflex-221 or Sikaflex-521, or a strong sealant tape like Eternabond or butyl tape would be perfect for this use-case. If using a non-sag sealant, ensure the sealant doesn't come into contact with the window bonding agent, as it may chemically degrade it.


Maintenance Tips: Keeping Your Campervan Roof in Top Shape

Campervan and RV roofs are often the most neglected part of your vehicle, as they're generally out of sight and hard to reach. However, you mustn't overlook inspection and maintenance of your roof as it's here that leaks are most likely to develop. A small leak can become a big problem if left for too long, leading to very costly repairs.


Inspection

It's a good idea to give the roof of your RV a proper inspection at least twice a year. You should also check up on your roof if you suspect damage might have occurred recently, like after a serious hailstorm or if you scrape a tree branch. This should include a thorough inspection of the whole roof, looking for cracks or pinholes and signs of aging. Discoloration, cracking, and peeling are a sign that it's time for a new coat of sealant. You should also check your seals around fixtures, seams, and the edges of the roof. Gaps, peeling, and degradation all necessitate a replacement of the seal using the same application techniques detailed above.

Resealing and Cleaning

How often to reseal your RV roof? Re-application of a sealant coat should be done according to the recommendation of the sealant manufacturer, regardless of whether you observe degradation. In general, acrylic roof coatings need to be reapplied every 2-3 years, silicone every 5-10, and elastomeric every 5. Lots of strong sunlight or harsh weather will necessitate more frequent reapplication. Follow the steps detailed above whether applying your first layer or reapplying a new layer.


Roofs should also be cleaned at least once a year, following an inspection. Debris contributes to the degradation of the roof through water retention and abrasion, whilst bird droppings and tree sap chemically degrade the roof. EPDM (rubber) roofs require a special cleaning solution (e.g. Dicor's Rubber Roof Cleaner), whilst other roofs can be cleaned with mild detergents or a generalized RV roof cleaner, like Beest USA's RV Roof Cleaner.


Professional Services and Final Thoughts

It's worth mentioning that everything we've discussed can be done professionally. Many RV workshops and maintenance services will offer fixture fitting as a service, which includes the application of sealant. They will also offer replacement of seals, as well as renewal of sealant coats. These services can be worth considering if you don't have the time or want to be sure your roof is maintained correctly to a high standard.


There's not a huge range in price when it comes to sealant products, and the most important thing is to choose the right sealant for your application from a reputable manufacturer. Be sure you know what your RV roof is made from and what kinds of sealant work best with the material. Many RV manufacturers provide a sealant call-out sheet, detailing the sealants used in the manufacture of the vehicle. This is a valuable resource when buying sealants for maintenance. You can often find call-out sheets for all an RV manufacturer's models on their website.


All the products we've linked in this article are well-regarded and widely used. Once you know what best suits your RV, choosing one of these products for your sealing and maintenance needs won't go amiss.


 

Don't forget to subscribe to The Van Conversion Newsletter for everything you need to get started with your own van conversion (we'll send you a free wiring diagram when you join).


If you're looking for some guidance with your van conversion, you might be interested in Roaming Home; The Comprehensive Guide for Converting Your Van Into a Campervan. In the 380-page book (or ebook), you'll learn directly from Shane how to convert a van into your dream home - no prior experience needed!


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Until next time.

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