What is the best type of sealant to use on your caravan/motorhome?

If you are new to the world of motorhomes or caravans, and have never had a problem with leaks in the past, you probably haven’t given much thought to what sealant to use on a caravan/motorhome.

With all the different things you purchase that go along with owning/towing a caravan, sealants are maybe something that seems unnecessary…. until you have a problem.

What do you do when you notice you have a leak?  I am not an expert, how do I fix a leak on my caravan?  Rather than calling out an expert, a small leak could be quick and easy to deal with on your own, using a caravan sealant.

In the following information, we are going to look at what a small leak is, why caravan sealants are used, the different types that are available, and why its important to have them before you need them!  We will help you find the right one for your caravan/motorhome needs.

Different types of caravan / motorhome sealants

There are three different types of most commonly used caravan / motorhome sealants and you can pick which is the best choice for you.

  1. Butyl Mastic Sealants (Also known as Caulking Compounds) – These types of adhesive sealants have been used the longest to fix leaks. These products are generally inexpensive, paintable and effective.  There are downsides to using this type of adhesive sealant and this would be that its only effective in the short term.   This is because the outer layer of the compound hardens as its exposed to the atmosphere which makes it perfect to provide dust/dirt and water resistance, however, it eventually dries too much and cracks.
  2. Silicone Sealants – Silicone sealants are generally the most used option for fixing leaks throughout the world. Silicone sealants were a major step-up from caulking compounds and were much more effective.  They offer immense strength and elasticity and keep your leaks fixed for much longer periods of time, than the caulking compounds did.   However, there are some downsides to choosing silicone sealants.  You need to be aware that using silicone sealants on an exterior leak/crack, can fail after a short period of time as it shrinks due to UV light and doesn’t adhere, and also due to movement with being on the road, this can weaken the joints.   Silicone sealants are best used on the interior cracks/leaks.
  3. Polyurethane Sealants – These are the latest technology in the caravan and motorhome industry. These are sometimes thought of being the most advanced and effective, as they provide exceptional durability and protection compared to other alternatives available on the market.  It is thought that because this type of fixing works perfectly with fibreglass, that is why these are so popular.   Fibreglass is the main material now that the newer caravans are built with. These are also popular because this type of adhesive sealant can be sanded, painted over and are UV resistant which makes them super durable.
  4. Mastic Tapes – Mastic tapes can come in various widths and depths. The most common size is 32mm wide.  Mastic Tapes are a pliable super sticky tape that can be stretched or sometimes doubled up for thicker applications.   Before sealant adhesives became more popular, these were generally used.  They are still a good and easy way to seal up leaks/cracks.
  5. MS Polymer Sealants – MS Polymer Sealants are the most modern way to construct caravans and motorhomes. These type of adhesive sealants were specifically formulated for the caravan and motorhome industry and are used globally to construct the well known brands. Being UV resistant, flexible, non-corrosive and bonds just about all different substrates, it makes the perfect product to use to stop a leak, fix a crack on your caravan, or even fitting accessories like bonding solar panels and satellites to roofs.


How to locate the leak on your caravan or motorhome

The first thing you need to do when you are attempting to fix a leak on your caravan or motorhome, is to find out where the source of water is leaking in through.   This can vary from van to van.  Older caravans may have problems with awning rails, and on motorhomes this could be aluminium framed lock doors or skirt rails. 

Leaking windows are generally quite easy to spot, however if your leak is coming through the roof or frame, these are a lot harder to pinpoint.    Window rubbers can be prone to leaking.

Because your caravan isn’t always parked on a completely flat or level surface, this means that the roof on a caravan or motorhome is not often completely horizontal.  Because of this reason, you will sometimes find that the real source of a leak is actually far away from where the water looks like it is coming in/appearing in your interior.

Finding the source of a leak can also be difficult due to possibly a very small crack, not visible to the naked eye, a missing screw, or a crack in a screw hole.  

If there are no clear signs of where the leak is coming from, we would suggest to remove or secure all valuables from the caravan, and then by using a spirit level on the roof, finding out the way the water is more likely to travel (by which way the roof slopes). 

You could perhaps try spraying small quantities of water onto the roof and having someone inside ready to look out for where/when they see the water entering the vehicle.

Leaks on the inside of the caravan are often easier to find.  There will usually be traces of water staining either on the ceiling or walls.

How to fix a leak

When fixing your own caravan leaks, or dealing with cracks, its always important to choose the right product.  It is also just as important, to ensure that you stick to some very good basic principles, and you can’t go wrong. 

  1. Always make sure you prep. This includes making sure that all of the old sealant or caulk is removed from the area that you are fixing.  A plastic scraper would be the perfect tool for this job.
  2. Then make sure that the area is completely clean. You will need to make sure that the surface is completely clean and dry before you start applying your chosen adhesive and sealant.   You can use a Cleaner/Surface Activator to make sure that it is completely clean.  You would apply the cleaner/surface activator with a lint free cloth for the best results.
  3. After the area has dried, you can then apply your adhesive or sealant.
  4. Before painting or finishing, please let the adhesive or sealant completely dry. You will see how long it takes for your chosen product to dry on their specification sheets.
  5. You could fun a final test before you set off, by spraying water over the problem areas to make sure that none of it seeps into the interior of your caravan or motorhome.

If you follow the steps above, you don’t have anything to worry about.  Leaks, cracks or any other issues with the structural integrity of your caravan can be dealt with by yourself at a much lower cost that calling out an expert.  If you have any further questions, or aren’t sure how to do a certain step of the process, at Gludog Limited we would be more than happy to help.  Contact us today by emailing us at  sales@gludog.com, or leave a message on our website, and someone will be in touch.



Please note these are the words and opinion of the author only. Neither the author nor the website can be held responsible for any errors or omissions. You should seek professional assistance if in doubt. 

© Gludog Limited 2021