exterior cladded house

How CPVC Brings Strength to Lightweight Building Materials

Posted by TempRite® Engineered Materials EMEA Team on 08/05/2021

TempRite Engineered Materials creates resin for manufacturing materials using Chlorinated Polyvinyl Chloride (CPVC.) This is achieved using a chlorination process in which PVC is processed with chlorine to add strength, stability and longevity.

As a result, the compounds formed from this base resin have gone on to serve the construction industry in a wide variety of applications, especially those that require an extra measure of strength or safety, in order for a product range to prolong its life cycle and safety attributes, such as modern architecture in high-end markets.

Why Lightweight Building Materials?

Product designers and engineers can factor the strength of CPVC into their product portfolio, especially those where a lightweight building solution is required:

Cost - Lightweight building materials generally offer vast cost savings to the manufacturer, the installer and the end user.

The Modular Advantage - Lightweight building materials are especially favoured by modular construction professionals, assembling structures off-site. This industry in particular has grown significantly in recent years, particularly in Europe and is looking to lightweight, adaptable materials to meet rising demand.

Safety - Lightweight construction materials are conducive to a safer construction environment, especially where it comes to transportation and installation.

Time Savings - Lightweight building materials are being employed more and more at every opportunity to keep tasks on the critical path running on schedule.

Sustainability - The construction industry faces increasing pressures every year to pursue more sustainable construction methods, particularly when it comes to the procurement of materials.

In order for CPVC to fulfil its potential as a lightweight building material, it must live up to each of the above advantages. Here is how TempRite CPVC gives manufacturers the advantage in construction without compromising on structural integrity.

How CPVC Achieves Heat Resistance

Much of CPVC’s core strength comes from its heat resistance. CPVC is formed by subjecting PVC to a chlorination reaction. Stiffening the molecular chain of the polymer, using large chlorine atoms, raises the softening temperature and gives CPVC an inherent strength and stability boost.

Thermal properties of thermoplastics

CPVC’s performance under heat allows product designers to think about lightweight building materials with a greater capacity for the following:

  • Higher softening temperature
  • Flame and smoke performance
  • Acid and oxidiser resistance
  • Thermoformability
  • Impact resistance
  • Adaptability

Maintaining Strength Outdoors

In order for a lightweight building material to maintain the structural advantage using CPVC, it must be able to display these inherent strengths outdoors, where various threats in our environment impact buildings every day. Arguably, our biggest threat is UV. UV is one of the most notorious causes of free radical degradation in our environment. Oxygen molecules are split, and the resulting free radicals can cause chain scission of polymers1, leaving large sections of building materials weakened.

A common misconception is that thermoplastics cannot withstand UV; however, CPVC’s UV resistance is built-in. CPVC is produced in a free radical process, so if the material were inherently susceptible to free radical degradation, it couldn’t even be produced.

To the manufacturer, it means CPVC can be applied where typically it would only be possible to think in terms of stone, wood or metal. Unlike most thermoplastics, CPVC is equipped to last against outdoor elements.

CPVC and Fire Safety

One of the most important considerations for construction professionals is fire safety, especially in the specification of building materials such as cladding. A common concern when considering lighter building materials is their capacity to withstand, contain or prevent the spread of fire. TempRite® CPVC resins’ fire and smoke performance characteristics listed below allow them to be applied in wider areas of construction.
  • Higher Flash Ignition Temperature
  • Better Flame and Smoke Properties
  • Lower Smoke Density
  • Better Flame Retardancy
  • Low Thermal Conductivity

Flash Ignition Temperature

A building material’s flash ignition point is when enough volatiles react with free radicals to catch fire, and is often assumed to be a low number when considering plastics for building materials. The table below shows CPVC’s Flash Ignition Temperature alongside other plastics and other lightweight building materials:

Flash Ignition Temperature

Flame Characteristics

It is commonly assumed that all plastics melt under high temperatures and in the case of fire, can produce flaming droplets and toxic byproducts as smoke, rendering them incapable of serving as fire safety material in buildings.

Burning drips from traditional plastic vs the protective layer of CPVC through crosslinking

When CPVC is exposed to fire, it dehydrochlorinates, releasing a natural flame retardant and producing a material which tends to crosslink instead of breaking down into smaller burnable pieces. Crosslinking of the molecules form a protective charred layer which is incapable of dripping and protects the CPVC material underneath from the action of the fire.

CPVC in Lightweight Building Applications


CPVC’s inherent strengths under high temperatures and loads makes it an ideal thermoplastic for panel extrusion on a mass scale.

In the case of lightweight materials, a foamed panel wall should be considered as a strong, adaptable and safe CPVC application, providing easy partitioning within temporary workspaces with optimum fire safety characteristics throughout.

Meanwhile, extruded outdoor panels allows product designers to recreate popular outdoor fencing styles, including gloss finishes. It’s inherent UV resistance and weatherability extends its service life beyond common plastics and wood.

Dark Coloured Siding

Outdoor sidings are typically limited by design, as in high temperatures, darker colors heat up more in direct sunlight, getting the material closer to or even beyond their Heat Distortion Temperatures faster, reducing its strength and stability sooner.

TempRite CPVC is proven in the polymeric siding industry throughout seasonal cycles in high temperature climates. Its consistent dimensional stability, even at temperatures of beyond 100℃ allows designers to expand their portfolio into darker styles to boost customer appeal.

Sided House 


Traditional exterior cladding, especially cladding made from popular vinyl is significantly susceptible to warping, sagging and fading under high temperatures. TempRite has offered many successful contractors a stronger alternative using CPVC.

Sided House

The beachside residences of Nags Head, California are subject to extreme outdoor conditions all year round, such as salt from the ocean, humidity and high temperatures.

A beachfront home with traditional wood shake siding required replacement; options considered were fiber cement, wood and TempRite technology. TempRite CPVC was chosen because of its proven performance on homes as an effective alternative to cladding over 10 years. It also allowed for a bold design option, opting for a darker shade of blue to make a statement. This was possible because of CPVC’s ability to resist damage from reflective light.

TempRite’s CPVC resin offers contractors more design freedom and security. As the head contractor for the Nags Head installation described:

“The best benefit of this product is that it resists damage from reflective light. It provides an alternative to customers who want the look of traditional clapboard cladding, without the higher risks of sheathing and framing rot beneath.”

- Frank Slowikowski (Gallop Roofing and Remodeling Inc.)

Visit our website and talk to a TempRite Engineered Materials expert to discuss your construction material requirements.


1 Chain scission is a term used in polymer chemistry describing the degradation of a polymer main chain. It is often caused by thermal stress (heat) or ionizing radiation (e.g. light, UV radiation or gamma radiation), often involving oxygen. During chain cleavage, the polymer chain is broken at a random point in the backbone to form two - mostly still highly molecular - fragments.

IUPAC, Compendium of Chemical Terminology,  2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–)


TempRite® Engineered Materials EMEA Team

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