Composite Caravan vs ACP Caravan: What’s the Difference?

In simple terms, a full composite caravan uses structural composite sandwich panels as part of the wall, roof, and often floor system. An ACP-clad caravan uses aluminium composite panels primarily as exterior cladding over a separate timber or aluminium frame. While both use composite materials, they differ in how they achieve structural strength, insulation, and weather resistance.

While many buyers assume all composite caravans are built the same way, the reality is that manufacturers can use very different construction methods. These differences can affect insulation performance, thermal comfort, structural rigidity, condensation resistance, durability, and overall weight.

While many buyers search for composite caravans, the more important question is whether the caravan uses true sandwich panel construction or ACP-clad framed construction.

Construction methods can vary significantly in:

• Insulation performance
• Thermal comfort
• Structural behaviour
• Condensation resistance
• Weight efficiency
• Long-term durability

Two caravan construction methods are commonly grouped under the word ‘composite’:

Structural composite sandwich panels are used as the wall, roof, and often floor system. In many full composite caravans, these panels provide structural strength, insulation, and weather resistance within a single integrated construction system.

3mm aluminium composite panels are used as external cladding over a timber or aluminium frame. Both use composite materials, but they use different construction methods, and understanding the difference matters.

In engineering and manufacturing, a composite material is a combination of two or more materials combined to achieve properties that a single material alone cannot provide.

That definition is extremely broad. Examples of composite materials include:

• Fibreglass reinforced plastic (FRP)
• Aluminium composite panels (ACP)
• Foam-core sandwich panels

Because the definition is so broad, the word composite by itself tells you very little about how a caravan is actually built.

A caravan advertised as ‘composite’ may still:

• Use conventional framing
• Contain timber in the wall structure
• Rely on cavity insulation
• Experience thermal bridging
• Use composite materials only as decorative exterior cladding

This is why buyers should look beyond the marketing terminology and understand the actual wall and roof construction system.

Full composite caravans use structural composite sandwich panels as the primary floor, wall and roof system rather than relying on a separate timber or aluminium frame.

A true composite sandwich panel caravan uses engineered insulated panels as the primary floor, wall and roof structure.

These panels typically consist of a lightweight foam core, bonded between structural skins, using engineered adhesive systems.

Common core materials include:

• XPS (extruded polystyrene)
• PET (polyethylene terephthalate foam)
• EPS (expanded polystyrene) foam

Common skin materials include fibreglass (GRP) skins and aluminium skins.

In this construction method, the panel performs multiple functions simultaneously:

• Structural stiffness
• Insulation
• Water resistance
• Panel stability
• Exterior/interior surface formation

Unlike traditional framed construction, the panel itself contributes significantly to the caravan body’s structural integrity. This is why many sandwich panel caravans are described as monocoque or semi-monocoque designs.

ACP stands for aluminium composite panel. These panels are typically made from two thin aluminium skins, bonded to a polyethylene core.

ACP is widely used in:

• Signage
• Architectural cladding
• Shopfronts
• Some caravan exteriors

ACP offers several advantages, such as:

• A clean flat appearance
• A consistent finish
• Easy fabrication,
• Broad colour availability

However, in most caravan applications, ACP is used primarily as external cladding over a separate structural frame. That frame is commonly made of timber, aluminium, or a hybrid.

In this system:

• The frame provides the structural strength
• The ACP provides the exterior finish
• Insulation is typically installed within wall cavities

This is fundamentally different from true composite sandwich panel construction.

One of the biggest advantages of true sandwich panel construction is continuous insulation. Because the foam core runs continuously through the panel, thermal performance is more consistent, cold bridging is reduced, and internal surface temperatures are more stable.

In framed caravans, insulation is interrupted by studs and framing, creating thermal bridges that allow heat to transfer through the wall structure. This means:

• Hotter interiors in summer
• Colder interiors in winter
• Increased heating/cooling demand
• Reduced comfort

This becomes especially noticeable in alpine conditions, hot inland climates, and long-term off-grid use.

What is thermal bridging?

Thermal bridging occurs when heat travels through conductive materials such as aluminium framing, steel framing, or poorly insulated structural elements.

In caravans, thermal bridging can create:

• Cold internal wall spots
• Condensation points
• Temperature inconsistency
• Reduced insulation effectiveness

True sandwich panel systems generally reduce thermal bridging because the insulation layer is continuous, and framing interruptions are minimised.

Condensation is one of the most overlooked issues in caravan ownership.
When warm, moist air contacts cold surfaces, water droplets form, particularly around framing junctions, corners, and poorly insulated sections. This can contribute to:

• Mould growth
• Odours
• Hidden moisture damage
• Long-term material deterioration

Because sandwich panels maintain more consistent internal surface temperatures, they generally reduce condensation risk compared with framed cavity wall systems. That said, ventilation, joint design, sealing quality, and overall engineering still play critical roles.

Structural rigidity influences:

• Towing stability
• Vibration resistance
• Squeaks and rattles
• Door alignment
• Fatigue performance over time

Composite sandwich panels often achieve high stiffness at relatively low weight, because the bonded panel acts as a stressed structural component.

ACP-clad framed construction depends more heavily on:

• Frame engineering
• Joinery quality
• Structural reinforcement

Both systems can perform well when properly engineered, but the structural principles differ significantly.

Water ingress remains one of the largest long-term risks in caravan ownership. In framed construction, moisture entering timber-framed sections can lead to rot, swelling, mould, and hidden structural degradation.

In sandwich panel systems, foam cores themselves generally do not rot. However, poor sealing or neglected damage can still affect:

• Adhesive bonds
• Joints
• Panel integrity

The key takeaway is that build quality and joint engineering matter just as much as material selection.

Weight efficiency is increasingly important in modern caravan design.
Composite sandwich panel systems can often achieve high stiffness, good insulation, and reduced structural weight simultaneously. This may improve:

• Payload capacity
• Towability
• Fuel efficiency
• Towing dynamics

However, not all sandwich panel caravans are lightweight, and not all framed caravans are heavy. Overall vehicle design still matters enormously.

No.

This is an important distinction.

ACP-clad framed caravans can still be well-built, durable, comfortable, and suitable for many users.

The issue is not that ACP is ‘bad’. The issue is that the word ‘composite’ alone does not accurately describe how a caravan is constructed. Consumers sometimes assume ‘composite’ means:

• Timber-free
• Fully insulated sandwich panels
• Monocoque construction
• Premium thermal performance

That may or may not be true. The term often lacks sufficient detail to properly evaluate construction quality.

The answer depends on many factors, including intended use, climate, budget, towing priorities, and build quality.

Composite sandwich panel construction may offer advantages in:

• Thermal consistency
• Reduced thermal bridging
• Condensation resistance
• Structural efficiency
• Weight optimisation

ACP-framed construction may still appeal through:

• Lower manufacturing complexity
• Proven traditional methods
• Competitive pricing

Ultimately, build quality, engineering, sealing systems, and manufacturer execution matter more than marketing terminology alone. A poorly engineered sandwich-panel caravan can still perform poorly, and a well-engineered framed caravan can still perform very well.

Instead of simply asking ‘Is it composite?’, buyers should ask more specific questions, such as:

1. Are the walls structural sandwich panels or framed walls with external cladding?
2. What core material is used in the wall and roof panels?
3. Is there timber in the wall or roof structure?
4. How is insulation installed?
5. What measures reduce thermal bridging?
6. How are joints and penetrations sealed?
7. What warranty coverage exists for water ingress and delamination?
8. How is condensation management addressed?

A quality manufacturer should be able to answer these questions clearly and confidently.

The word ‘composite’ can describe advanced structural sandwich panel systems or simply thin exterior cladding materials.

A caravan built from true composite sandwich panels is fundamentally different from a framed caravan clad in 3mm ACP, particularly in insulation consistency, thermal bridging behaviour, condensation resistance, and structural integration.

That does not automatically make one ‘good’ and the other ‘bad’. But it does mean consumers should look beyond marketing language and understand how a caravan is actually constructed. Because in the end, understanding the engineering behind the wall and roof system matters far more than relying on a single marketing word.

At Liner, we supply advanced materials used in the manufacture of composite sandwich panels for caravans, motorhomes, commercial vehicles, and specialty vehicle applications.

Our solutions include composite skins, foam cores, adhesives, and high-performance panel system materials designed for long-term durability, thermal performance, and lightweight construction.

Contact our team to discuss composite panel material solutions for your application.