A cracked or lifting seal around a roof vent, window or exterior fitting may seem like a small problem, but it can let water into places you can’t easily see. Once moisture gets behind the lining, a simple resealing job can turn into a much bigger repair.

The tricky part is knowing what to use. Lap sealant and silicone may look similar in the cartridge, but they’re designed for different jobs. Self-levelling lap sealant is used on suitable horizontal roof areas, while non-flowing silicone stays where it’s applied and is better suited to certain glass, aluminium and metal joins.

Before you start, check where the seal has failed, whether the surface is horizontal or vertical and which materials you’re sealing. Those three things will usually point you towards the right product.

Why Caravan Seals Need Regular Attention

Caravan seals have a lot to deal with. Every trip brings movement and vibration, while the exterior is exposed to rain, UV and changing temperatures. Over time, even a well-applied seal can start to crack, harden or pull away.

Roof vents, hatches, windows, corner joins and other exterior fittings are all worth checking. Look for raised edges, small gaps and sections that feel dry or brittle. Water marks or a damp smell inside the caravan can also be a warning sign, although the point where water appears may not be where it entered.

A seal doesn’t need replacing just because it looks old. If it’s still flexible, firmly attached and free from cracks or gaps, it may be doing its job perfectly well. Focus on areas that are lifting, splitting or allowing water to work its way underneath.

Lap Sealant or Silicone: Which One Do You Need?

The easiest way to tell these products apart is by looking at how they behave after application.

Self-levelling lap sealant spreads slightly as it settles. This helps it cover horizontal joins, screw heads and the edges of rooftop fittings. Because it flows, it should be kept to horizontal surfaces.

Non-flowing silicone stays closer to the bead you apply. It gives you more control on suitable vertical and horizontal joins, such as certain glass, aluminium and metal areas.

If you’re resealing around a roof vent, a lap sealant may be the right choice. For a compatible aluminium frame or glazed area, a non-flowing silicone may be more suitable. The location and materials matter more than the colour of the cartridge.

Dicor Lap Sealant for Caravan Roofs

The Dicor Lap Sealant Suit Rubber Roofs is a white, self-levelling sealant made for suitable horizontal roof applications.

It can be used to form a flexible seal around areas such as:

• Roof vents and hatches
• Vent pipes
• Screw heads
• Selected roof edges and overlapping joins
• Other roof-mounted fittings

It adheres to materials commonly found on caravan roofs, including compatible rubber roofing, fibreglass, wood, aluminium and steel. This makes it particularly useful where different materials meet.

Because the sealant levels itself, it isn’t suitable for an upright window frame or a vertical join on the side of your caravan. It may run before it has time to cure.

Before using it, check which type of roof is fitted to your caravan. The term “rubber roof” can refer to different roofing membranes, and an existing coating or previous repair may affect which products can be applied over it.

Lap sealant also needs a sound surface underneath. It can reseal a suitable fitting or join, but it won’t repair a loose vent, damaged roof panel or soft section of roof.

Bostik V60 for Glass, Aluminium and Metal

Where you need the sealant to stay in place, Bostik V60 Structural Silicone may be more suitable.

V60 is a non-flowing, neutral-cure silicone used for glazing and weatherproofing. It bonds to materials including glass, mirrors, painted and anodised aluminium and composite metal panels. Think of areas such as compatible window frames and selected metal joins rather than broad sections of the caravan roof.

Once cured, V60 remains flexible, so the seal can cope with the movement and temperature changes that come with caravan travel.

It isn’t suitable for every material. Bostik advises against using V60 on copper, brass or polycarbonate sheeting. This is particularly important around skylights and roof hatches, as some clear caravan fittings are made from polycarbonate. Don’t assume that clear silicone will automatically suit a clear plastic fitting.

White, Clear or Black?

Carac stocks V60 in three colours. The product itself is the same, so the choice comes down to where it will be used and how you want the finished joint to look.

• White V60 generally blends in best with white caravan panels and light-coloured frames.

• Black V60 is a better match for black window frames, dark aluminium and other black exterior fittings.

• Clear V60 can be useful where two different colours meet and neither black nor white would blend in. Clear silicone doesn’t disappear completely, though. The size and neatness of the bead will still affect the finished result.

Preparing the Area Before You Start

A lasting repair starts before you pick up the caulking gun. Fresh sealant won’t bond properly to dirt, moisture or an old seal that is already lifting away.

Inspect the entire join first, not only the most obvious crack. If the fitting moves or the surface underneath feels soft, have the area checked before applying more sealant.

Remove any loose material carefully, taking care not to damage the roof membrane, paintwork or fitting. Clean the area with a product suitable for the surface and allow it to dry completely.

Before applying the product, check:

• That it suits both materials being joined
• Whether the surface is horizontal or vertical
• Whether it can be applied over the existing sealant
• The recommended temperature and weather conditions
• How long it needs before being exposed to rain

Avoid adding a thick new layer simply because the old seal looks untidy. If the product underneath is lifting or no longer bonded to the surface, covering it may only hide the problem without fixing it.

Choosing a Caulking Gun

A traditional caulking gun can be awkward to use inside a caravan or close to a wall, cabinet or rooftop fitting. Compact rodless guns take up less space behind the cartridge, making it easier to reach tighter areas.

The Siligun Rodless Caulking Gun has a compact ABS body and is a practical option for occasional maintenance jobs. Its small size also makes it easier to store in a caravan toolbox.

For more regular use, the Siligun Pro Cast Aluminium Caulking Gun has a stronger aluminium body and a higher 24:1 thrust ratio. This provides more force when dispensing thicker products. It also has a no-drip design to help stop excess sealant continuing to flow when the trigger is released.

Cartridge dimensions can vary, so check that your chosen sealant fits the gun before ordering.

When Is It Better to Call a Caravan Repairer?

A small repair is often manageable when you can clearly see where the seal has failed and the surface underneath is still sound.

Call a caravan repairer if the source of the leak isn’t clear, a fitting needs to be removed or there are signs that water has already reached the roof or wall structure. Soft sections, swollen panels, staining and a persistent damp smell can all point to a bigger problem than the visible seal.

If your caravan is still under warranty, check the conditions before carrying out the repair yourself.

Need Help Choosing the Right Sealant?

The right product depends on where you’re using it and which materials you need to seal. At Carac, we stock Dicor Lap Sealant, Bostik V60 in white, clear and black, and compact Siligun caulking guns for caravan maintenance and repairs.

Not sure which one suits your job? Pop into our Dandenong South store or give us a call on (03) 9794 7977. We’ll help you work out what you need before you get started.

Safe travels and happy caravanning!