Two brochures can use the word composite for completely different walls. One means the cladding, the other means the whole structure.
Cladding and frame are two different things
A caravan wall has two jobs: hold the van up, and keep the weather out. In a framed van those jobs belong to different parts. The frame holds it up, the cladding keeps weather out, and the insulation sits between the frame members. In a structural composite van, one bonded panel does all three.
When a dealer says a van has composite walls, ask whether the composite is the cladding or the structure.
The five builds, side by side
Each build is covered under the same four headings: weight, insulation, water ingress and repair.
Stucco aluminium over a frame
Also called: Stucco, stuco, peened or embossed aluminium cladding
A thin aluminium sheet with a dimpled finish, fixed over an aluminium or timber frame. Insulation sits in the cavity between the frame members. The dimples scatter the light, so the sheet hides the ripples and knocks a flat sheet this thin would show. It is the long-standing Australian caravan wall and the most common build in a yard.
- Weight
- The sheet is thin, so the cladding is light. Most of the wall's weight is in the frame and the inside lining. Two stucco vans of the same size can be a long way apart, depending on the frame.
- Insulation
- Insulation is whatever fills the cavity, usually a batt or a foam block. The frame members bridge the wall, and an aluminium frame conducts heat well. So the wall performs a bit below the rating printed on the insulation.
- Water ingress
- The sheet keeps water out. Water gets in at the joins and fasteners: every window, hatch, awning rail and screw is sealed with sealant. Sealant is a maintenance item, so check it every year on this build.
- Repairability
- Stucco is easy to repair. A panel section can be replaced, a panel beater can work the material, and any town with a caravan repairer has the skills. Frame damage is a bigger job, because the sheet has to come off first.
Words that mean this on a spec sheet: stucco aluminium, aluminium cladding, peened aluminium, meranti or alloy frame.
Alucomp aluminium composite cladding
Also called: Alucomp, alucobond, ACP, aluminium composite panel
Two thin aluminium skins bonded either side of a plastic core, fixed over a frame much like stucco. The sandwich is much stiffer than a bare skin of the same weight, so the sheet stays dead flat. Alucomp is usually cladding, and the frame does the structural work.
- Weight
- Per square metre it is close to stucco sheet, a little heavier or lighter depending on the core and skins. The frame still carries the load, so alucomp on its own rarely changes the tare by much.
- Insulation
- The core is thin and adds very little. What fills the frame cavity behind it decides how the wall performs.
- Water ingress
- Water gets in at the same places as on stucco, but larger flat sheets leave fewer seams to seal. The aluminium skin does not absorb water. A damaged skin can let water sit against the core where you cannot see it.
- Repairability
- Alucomp is harder to repair than stucco and easier than a structural panel. A dent cannot be beaten out, so it usually means replacing a section. A repairer can still get to the frame behind it.
Words that mean this on a spec sheet: alucomp, composite cladding, aluminium composite panel, one-piece walls.
Full composite sandwich panel
Also called: Composite panel, fibreglass sandwich, structural panel, frameless
A thick foam core bonded between two structural skins, usually fibreglass and sometimes aluminium. The panel carries the load, so there is often no separate frame inside it. Walls, roof and floor are usually bonded together, and vans built this way are often described as one-piece or frameless.
- Weight
- One panel does the job of a frame, a batt, a cladding sheet and an inner lining, so the wall is light for its stiffness. The rest of the van usually outweighs the walls (see which build is lighter, below).
- Insulation
- The foam core runs unbroken across the panel, with no frame members bridging it. That matters more than the rating of any one material.
- Water ingress
- There is no timber to rot, and the core does not absorb water. The fault to know is delamination: water or heat breaks the bond between skin and core, and the panel loses stiffness. It shows as a soft spot or a bubble.
- Repairability
- The panel is structural, so a serious hit needs a specialist. The repair can mean cutting out a section and re-bonding it. Ask where the nearest repairer is before you buy, because for this build the answer varies by state.
Words that mean this on a spec sheet: composite, sandwich panel, structural panel, frameless, fibreglass, XPS or foam core.
Timber frame
Also called: Meranti frame, timber framed walls
A timber frame, usually meranti, clad outside and lined inside, with insulation between the members. It is the oldest build in the Australian industry, and nearly every repairer knows how to work on it.
- Weight
- A timber frame is heavier than an aluminium frame doing the same job. Van size still changes the weight far more than the frame material does.
- Insulation
- Same cavity principle as any framed wall. Timber bridges less heat than aluminium, which helps on a hot day.
- Water ingress
- Timber that stays wet rots, and rot in a wall frame is structural, expensive and often hidden until it is advanced. It starts only when water gets in and stays in. Good sealant and regular maintenance keep it out.
- Repairability
- Timber is the easiest and cheapest build to repair. The materials are ordinary, the skills are everywhere, and a section of frame can be cut out and replaced.
Words that mean this on a spec sheet: meranti, timber frame, hardwood frame.
Fully welded frame
Also called: Welded alloy frame, welded steel frame, one-piece frame
The frame members are welded into one structure, then clad. Aluminium and steel are both used. Welding is for corrugated roads: corrugations can work a screwed joint loose over thousands of kilometres, and a welded joint has no fastener to loosen.
- Weight
- A welded aluminium frame weighs about the same as a screwed one. A welded steel frame is heavier and stronger, which is why it turns up under vans built for rough country.
- Insulation
- Welding does not change the insulation. Metal frame members still bridge the wall.
- Water ingress
- Metal frames do not rot. Steel can corrode where its coating is broken, so ask about hot-dip galvanising and how well the coating survived the build.
- Repairability
- A repair needs a welder, and an aluminium frame needs one who works in aluminium. That is easy in a capital city and harder in remote areas.
Words that mean this on a spec sheet: fully welded, welded alloy, hot-dip galvanised, one-piece frame.
Which build is lighter?
The van's published tare answers it. The wall material on its own is a poor guide.
A full composite sandwich body is generally the lightest way to build a wall for a given stiffness. An aluminium frame is lighter than a timber frame doing the same job. But the walls are only a small part of a caravan's weight. The chassis, the suspension, the water tanks, the batteries and the fitout usually add up to more.
So a large composite van can weigh more than a small aluminium-clad one, and both can be well built.
What the published weights show
Grouped by wall build, the published tare weights of listed vans overlap a lot.
| Wall build | Lightest to heaviest tare |
|---|---|
| Composite | 950kg to 3,350kg |
| Aluminium composite panel | 480kg to 2,980kg |
| Aluminium | 715kg to 4,540kg |
| Fibreglass | 380kg to 3,400kg |
| Sandwich panel | 1,000kg to 3,136kg |
| Aluminium frame | 700kg to 2,990kg |
| Timber | 1,935kg to 2,988kg |
| Aluminium composite | 980kg to 2,875kg |
| Steel | 1,140kg to 2,600kg |
| Composite panel | 550kg to 1,910kg |
| Galvanised steel | 700kg to 1,200kg |
| Bonded zinc-coated steel panel | 1,440kg to 1,520kg |
| Composite - no timber frames | 590kg |
| Aluminium frame with insulated fibreglass panels | 2,800kg |
| Composite with aluminium frame | 850kg |
Across every build here, published tare runs from 380kg to 4,540kg. Van size and fitout change that figure far more than the wall build does.
Caravans under 2,500kg ATMLightweight caravansCaravans by ball weight
How to read construction off a spec sheet
Look for these five things on a spec sheet.
- 1
Check what 'composite' means on that sheet
Composite on a spec sheet can mean the cladding, the structure or both. Look for a frame anywhere on the same sheet. If a frame material is listed, the composite is cladding on that frame. Bonded walls, one-piece construction or no frame at all mean a structural panel.
- 2
Frame material and frame method are separate lines
Meranti, alloy or steel is the material. Screwed, riveted or fully welded is how it is held together. If the sheet lists one and not the other, ask for the missing one.
- 3
Insulation is rated for the material rather than the wall
The rating is measured on the insulation itself, and it does not count the frame members running through the wall. Use it to compare vans built the same way.
- 4
Tare is the weight figure to trust
No wall build has a weight you can put in a calculator. Tare is the maker's published weight for the model, and the compliance plate gives it for the van in front of you.
- 5
Watch for a name that is not a material
Makers give their wall builds product names. Ask what is in it, in materials. If the answer is the name again, treat the sheet as silent on construction.
What to check on the van in front of you
Eight checks, in the order you would do them standing at the van. They work on a new van in a yard or a ten-year-old one in a driveway, and none needs a tool.
- 1
Put your eye along the wall from the front corner
Sight down the side of the van from one corner, the way you would check a plank for straightness. Ripples, waves or a bulge point at a wall that has moved. On a composite panel, a bulge can mean delamination.
- 2
Press the wall low down, near the floor join
Press firmly with the flat of your hand at the bottom of the wall, in each corner and under each window. It should feel solid everywhere. A soft spot means water damage in a framed wall or delamination in a panel, often before either is visible.
- 3
Follow every sealant line
Check the sealant around every window, hatch, light, awning rail and corner join. Look for shrinkage, cracks, gaps, or a bead pulled away from one side. Water gets into every build at these joins.
- 4
Look at the inside of the same spots
Inside, check the ceiling and wall lining under every roof hatch, air conditioner and window. Staining, a lifted lining edge, a musty smell or screws rusted from behind all mean water has been there.
- 5
Open a locker and look at the raw edge
External lockers and the wardrobe base often show the wall cut in cross-section. That is the quickest way to see whether there is timber, alloy or a foam core inside.
- 6
Ask what the walls are, then ask what the frame is
These are two questions, and the answers are often different materials. If the answer matters to you, ask for both in writing on the order form.
- 7
Ask where it gets repaired
Ask the dealer who repairs a damaged wall on that van, and where. A common build has a repairer in every town. A structural panel may have one in your state.
- 8
Check the compliance plate against the brochure
The plate on the van is the legal figure. If the plate and the brochure disagree on tare, the plate counts. Dealer-fitted extras can make a van heavier than any published figure.
None of this replaces an inspection
These checks find the obvious problems. On a used van, an inspector with a moisture meter finds what a hand cannot. Our pre-delivery and used-buying checklists cover the rest of the van.
Match the build to how you will use it
What matters most for four common kinds of trip:
- Sealed roads and caravan parks. Any of these builds will do the job, so choose on weight and price. Check tare against your car and buy the layout you like.
- Long stretches of corrugated dirt. How the structure is joined matters more than what it is clad with. Welded frames and bonded panels both remove fasteners that corrugations work loose. Ask how the walls attach to the floor and the roof, which is where movement shows first.
- Heat, cold, and staying put for weeks. Continuous insulation with nothing bridging it is what makes the difference, which favours a structural panel. In a framed van, ask what fills the cavity and how the frame members run.
- Remote travel where a repair has to happen locally. Choose a common build. A country workshop can usually fix it quickly, which matters a long way from a capital city.
Whichever build you choose, the van's weight has to suit your car first.
Common questions about caravan construction
What is the difference between stucco and alucomp caravan walls?
Stucco is a single thin aluminium sheet with a dimpled finish, fixed over a frame. Alucomp is an aluminium composite panel: two thin aluminium skins bonded either side of a plastic core. It is fixed over a frame in much the same way. Alucomp stays dead flat, while stucco is dimpled to hide the ripples a thin flat sheet would show. Alucomp also comes in larger sheets, so a wall has fewer joins to seal. Both are cladding, and the frame behind them carries the load. So neither one, on its own, tells you how well a van is built or how heavy it is.
Which is lighter, a composite caravan or an aluminium one?
The published tare of each van settles it. A full composite body is generally the lightest way to build a wall for a given stiffness. One foam-cored panel replaces the frame, batts, cladding and lining. An aluminium frame is lighter than a timber frame doing the same job. But the chassis, suspension, water tanks, batteries and fitout usually outweigh the body. So a large composite van can be heavier than a small aluminium-clad one.
Do composite caravans still get water damage?
Yes. Water gets in at the same places as on any other van: windows, hatches, awning rails, service points and corner joins. A composite panel has no timber to rot, and its foam core does not absorb water. So a leak is usually a repair job rather than a structural one. The fault to watch for is delamination, where water or heat breaks the bond between skin and core. It shows as a soft spot or a bubble, which is why the checklist has you press the wall low down.
Is a timber-framed caravan a bad buy?
No. Timber framing is the most repairable build in the country and the cheapest to have repaired. Its one real weakness is rot. Rot in a wall frame is structural, and often advanced before you can see it. Check and renew the sealant on schedule and fix leaks quickly, and a timber frame does its job.
Does a fully welded frame matter for corrugated roads?
Yes, that is one of the reasons welded frames exist. A screwed or riveted joint depends on the fastener staying tight, and thousands of kilometres of corrugations work fasteners loose. A welded joint has nothing to come loose. Plenty of vans cross the country on screwed frames, but a welded frame removes that one kind of failure.
How do I tell what a caravan is built from if the spec sheet does not say?
Ask two separate questions: what the walls are clad with, and what the frame is made of. Composite cladding over a timber frame is a timber-framed van. If the answer to either is a product name, ask what is in it. On the van, external lockers and the wardrobe base often show the wall cut in cross-section. That shows whether there is timber, alloy or foam inside.
Does construction type affect what my car can tow?
Construction only matters through the tare weight of the van in front of you. Your car's braked towing capacity has to cover the van's ATM (Aggregate Trailer Mass). Your car's payload has to cover the ball weight plus everyone and everything in the car. Two vans built completely differently can share an ATM. Put the van's published figures into a tow check.
This page is general information about how caravans are built, and rates no manufacturer on construction.