Australian consumers only : USA & World enquires & information visit spicoatings.com - Authorised Australian & New Zealand Distributor
Converting a Toyota Coaster bus into a motorhome is a smart project. You gain space, durability and the ability to travel anywhere. But one issue shows up fast once the build is finished.
Heat.
Large metal roofs sitting in the sun act like a giant radiator. Once the metal heats up, the roof starts dumping that heat straight into the living space. Air conditioners end up working overtime, batteries drain faster and comfort drops quickly.
So the real question is simple.
What coating actually stops the heat from entering the roof in the first place?
Most buses are built with thin steel or aluminium roofs. Those materials conduct heat extremely well.
When parked in the sun:
Once the metal is hot, the insulation inside the bus is already fighting a losing battle.
A typical dark roof can reach 70°C or more in summer conditions. Even lighter coloured roofs still absorb a large amount of infrared heat.
For a motorhome owner that means:
The smartest approach is not just cooling the air. The smarter approach is stopping the heat load at the roof surface.
Most people think painting the roof white will solve the problem. It helps slightly but it is not the full solution.
Standard automotive or house paints mainly deal with colour and UV protection. They do not actively block infrared radiation, which makes up over half of the sun’s energy.
That means the roof still absorbs large amounts of heat.
Even white paint eventually heats up and transfers that heat into the metal underneath.
Colour alone is not enough. The coating needs to manage heat behaviour.
The coatings that work best on vehicle roofs are designed to manage three things:
When these three factors combine, the roof stays significantly cooler and the interior heat load drops.
This is why specialised ceramic insulation coatings have become popular in transport, marine and industrial applications.
One example used globally is Super Therm®.
Unlike normal paint, ceramic coatings use microscopic ceramic compounds that influence how heat behaves at the surface.
In simple terms they:
Even though the coating is very thin, the thermal behaviour of the surface changes dramatically.
For vehicles and transport roofs this approach has been used on:
The goal is always the same. Reduce heat load before it reaches the interior.
Motorhome conversions have a unique challenge.
Unlike houses, you have:
If heat enters the roof structure, your cooling system is constantly playing catch up.
By reducing roof temperature at the surface you gain several advantages:
Less heat entering the roof means cooler internal air.
Your AC runs less often and consumes less power.
Lower energy demand is critical when running on solar and batteries.
Sleeping, cooking and living become far more comfortable in hot climates.
One overlooked fact is that roof temperature directly drives interior temperature.
If the roof surface can be kept dramatically cooler, the interior heat load drops quickly.
Field trials in buildings and transport applications regularly show significant reductions in surface temperatures when heat blocking coatings are applied.
For a motorhome roof exposed to full sun, this difference can transform the comfort level inside the vehicle.
Motorhome builders often experiment with different approaches.
Cheap and simple but only moderately effective.
Reflect sunlight but still conduct heat through the metal.
Helpful but the heat has already entered the metal skin.
Effective when stationary but useless while driving or parked without shade.
The most effective strategy is usually combining insulation inside the roof with a heat blocking surface coating outside.
For most DIY builders the practical setup looks like this:
This combination addresses both sides of the heat transfer problem.
Stop the heat at the surface, then slow any remaining transfer inside the structure.
When converting a Toyota Coaster into a motorhome, people often focus on cabinetry, solar systems and layouts.
But comfort is controlled by one thing more than anything else.
The roof.
If the roof absorbs heat, the whole vehicle becomes difficult to cool.
If the roof blocks heat, everything inside works better.
Cooling systems work less, batteries last longer and the interior stays comfortable even in harsh summer conditions.
That is why serious transport operators, railways and marine vessels focus on surface heat control first before trying to manage the heat after it has already entered the structure.
References
How to Keep Your Caravan, Bus and RV Cool
https://neotechcoatings.com/protective-coatings/industry-uses/transportation/how-to-keep-your-caravan-bus-and-rv-cool/
Cool Roofs – Energy.gov Guide
https://www.energy.gov/energysaver/cool-roofs
Cool Roofs and Heat Reduction in Buildings – Australian Government
https://www.yourhome.gov.au/passive-design/cooling
Every summer the same pattern repeats. Temperatures climb. Air conditioners run longer. Electricity demand spikes. And households open their power bill wondering how it got so high. Most advice focuses…
Passive Cool Roofs That Cut Heat Load Before It Enters Your Building A cool surface is not a new idea. What’s new is treating the roof as a thermal management…
The U.S. Energy Authority has long promoted reflective or “cool roof” technologies as a way to reduce solar heat gain in buildings. These systems typically rely on light-coloured surfaces that…
A report titled “Impact of Roof Colour and Insulation on Thermal and Energy Performance of Residential Buildings” produced by Deakin University in collaboration with the Insulation Council of Australia and…
Super Therm® is a multi-ceramic heat-blocking insulation coating designed to reduce solar heat load on exposed surfaces. When applied to metal structures such as aluminium ship and boat roofs, it…
In the insulation world, spray foam is often promoted as the ultimate solution. It delivers high R-value per inch, excellent air sealing, and the ability to fill cavities and irregular…
“Nano ceramic technology.”“Insulative ceramic particle.”“Advanced ceramic coating.” The language sounds precise. It sounds engineered. It sounds proven. It sounds authentic. But ceramics are not a single technology. They are one…
Thermal bridging is one of the most underestimated causes of energy loss in buildings. It does not matter how thick your insulation is.If heat finds a path around it, performance…
Laboratory testing matters. ASTM data matters. Controlled conditions matter. But buildings do not operate in laboratories. They operate in Adelaide summers. Middle East heat. US desert airports. Marine environments. Transportable…
Walk outside on a 35°C day.Touch a dark metal roof. It is not 35°C. It is 60°C, 70°C, sometimes more. Ambient temperature is the air.Surface temperature is radiation plus absorption…
Most insulation conversations ignore one hard truth. The substrate matters. Metal, concrete and wood do not behave the same under solar load. If you do not understand surface science first,…
Most people still believe insulation must be thick to work. Batts. Boards. Foam. Layers of material measured in tens or hundreds of millimetres. Then along comes a coating that cures…
Most buildings don’t fail because of insulation thickness. They fail because of timing. Thermal inertia and lag time are where real performance is won or lost. If you ignore them,…
Most conversations about building comfort revolve around insulation thickness and R-values. That is only part of the story. Comfort is not just about slowing heat flow. It is about how…
If you do not understand how heat actually reaches a building, you will never control it. Most discussions around insulation jump straight to R-values and bulk thickness. That misses the…
The industry is trained to think thicker equals better. More R-value. More bulk. More layers. But thickness only addresses one part of heat transfer. It deals primarily with conductive flow…
Most insulation conversations are built on one assumption. That insulation works by absorbing heat. It does not! And that misunderstanding is costing buildings money, performance and long-term resilience nor planning…
In the late 1980s, satellites were picking up something most building codes still ignore. Cities were glowing. Roofs, roads, metal structures and concrete were absorbing solar radiation all day and…
The Problem Most People Miss Heat does not move one way. It transfers through radiation, conduction and convection. Most “cool roof” products focus on one or two levers. Usually reflectivity…
Most of the building industry still worships R-value. Higher number. Thicker insulation. Problem solved. That logic worked in the 20th century. It won’t work in a future 2050 climate. If…
Most building conversations focus on R-values, insulation thickness and HVAC capacity. But the real fight starts at the surface. Surface heat behaviour determines how much solar energy actually enters the…
Cool roofs are being pushed hard. White surfaces. High reflectance. Lower surface temperatures. Reduced urban heat. All valid. But most coverage stops at the surface and ignores fundamental heat physics…
Most buildings are designed to manage heat after it is already inside. Air conditioning systems grow larger. Energy bills climb. Equipment cycles harder. Maintenance increases. Occupants complain. Asset life shortens.…
The market is shifting. Energy is expensive. Carbon is regulated. Tenants are informed. Investors are cautious. And buildings that overheat are liabilities. A thermally unstable building bleeds money. It relies…
Most of the buildings and industrial assets operating today were never designed for 45°C heatwaves, extended UV exposure, rising energy costs, or aggressive corrosion cycles. Yet that is exactly what…
What Actually Matters When Heat and Flame Are Involved Fire performance is one of the most misunderstood parts of building materials. A product can claim to be “fire resistant,” “non-combustible,”…
Every coating system eventually faces the same test. Sun. Moisture. Movement. Contamination. Time. The real question is not whether a surface will degrade. It is how fast, how predictably, and…
Steel fails for two main reasons. Heat and corrosion. We treat them as separate problems. They are not. If you allow solar radiation to superheat a steel surface, you accelerate…
The Problem Across Australia and New Zealand, thousands of buildings are operating under ageing metal roofs. Warehouses. Schools. Modular buildings. Container offices. The default solution when performance drops is expensive…
Heat blocking coatings work. But only when they are installed correctly. Too often, performance gets judged on the product when the real issue is application. A high-performance coating applied poorly…
Thickness has dominated insulation thinking for decades. More bulk. More R-value. More material. But what if performance is not about thickness at all? A 0.25 mm dry film thickness sounds…
If film thickness is wrong, performance is wrong. It’s that simple. In high-performance coatings, especially insulation and corrosion systems, dry film thickness is not a suggestion. It is a specification…
Coatings do not fail because of chemistry.They fail because of surfaces. You can have the most advanced insulation or corrosion system in the world, but if the substrate is contaminated,…
Application method is rarely discussed in technical detail, yet it directly affects coating performance. Spray and roller are not just different tools. They influence film build, density, surface profile, curing…
Extreme heat is not a theory problem. It is a surface problem. Roofs hitting 70°C. Steel containers becoming ovens. Jet bridges, rail carriages, mining camps and defence assets absorbing solar…
If you are specifying coatings for roofs, steel structures, containers or façades, the real question is simple. Will it still perform in 10, 20 or 30 years? Accelerated weathering exists…
Everyone talks about performance on day one. Very few talk about performance after year ten. In building science, coatings and insulation systems are often assessed on initial lab values. Reflectance.…
What Actually Proves Performance? In the coatings and insulation industry, everyone claims performance. Energy savings. Heat reduction. Fire resistance. Durability. But there is a clear line between manufacturer testing and…
Thermal cameras do not guess. They measure infrared radiation and convert it into a visible temperature map. When used correctly, they expose one simple truth: That difference changes everything for…
There’s a big gap between what a product says it does and what it can actually prove. In the coatings and insulation space, that gap costs money. It costs performance.…
Most people look at one number and think they understand performance. That is the mistake. Solar reflectance reports are technical documents. If you read them properly, they tell you exactly…
In building science, the lab is controlled. The surface is not. In the lab, temperature, humidity, air movement and radiation are isolated and repeatable. On a roof in Adelaide, Dubai…
Government field trials carry weight. They are independent, structured, and often influence policy, funding and specification decisions. But they are also frequently misunderstood. If you do not read them properly,…
There is a lot of noise in the insulation coatings space. Big claims. Impressive percentages. Selective test data. If you want clarity, you need to understand what ASTM and ISO…
Why surface science must now shape planning law Urban heat is no longer a design inconvenience. It is a public health, infrastructure and energy problem. Cities are running hotter because…
We are not designing for yesterday’s climate anymore. Australia is already experiencing longer heatwaves, higher peak temperatures, intense rainfall events and elevated night-time temperatures. Buildings constructed to 1990s logic are…
Energy ratings were built for a different era. They measure compliance. They don’t measure real-time solar punishment on a surface at 2:30pm in January. That gap matters. The Problem: Ratings…
For decades, building performance has been judged by a narrow set of metrics. Mostly R-values. Sometimes U-values. Occasionally energy modelling outputs that look precise but ignore how heat actually behaves…
For decades, the industry has defaulted to thicker insulation, higher R-values and bigger HVAC systems. Yet governments around the world are now testing something far more direct. Control the surface.Control…
Social housing is meant to protect the most vulnerable. Yet across Australia and globally, many social housing projects are thermally fragile. They meet minimum code. They tick the box on…
Urban heat is not a future problem. It is already driving higher energy demand, worsening heat stress and increasing night-time temperatures in our cities. If councils want measurable impact, they…
Where They Succeed and Where They Fall Short Cool roof policies are now embedded in building codes across the US, Europe and parts of Australia. On paper, they make sense.…
White roofs are everywhere. High solar reflectance. Lower surface temperatures. Ticked compliance boxes. On paper, that looks like progress. In reality, reflectance is only one part of heat transfer. If…
Passive Cool Roofs That Cut Heat Load Before It Enters Your Building A cool surface is not a new idea. What’s new is treating the roof as a thermal management…
Looking to join one of the world’s leading coatings companies. Contact us if you’re a quality applicator looking for new products and markets!
Genuine SPI COATING PRODUCTS can only be purchased from SPI Authorised Representatives displaying the SPI Authorised Logo. Note: All reduced energy claims - results may vary in different conditions and locations.
