The most common components of a building envelope perform important functions, but they do not always meet their true potential. To that end, various types of plastic materials can help building owners achieve the efficiency they require. For example, extruded polystyrene (XPS) foam insulating sheathing offers many benefits due to the way this product is manufactured. Energy-efficient, easy to install, lightweight, and recognizable in its blue, pink, or green colors, the specification of extruded polystyrene foam sheathing may allow the use of a single product to create a continuous layer of thermal and moisture protection on a building’s walls, thereby contributing to energy efficiency.

Now, let’s see the process and some special features of XPS

XPS Process 0407-1

Creating Extruded Polystyrene

Extruded polystyrene foam board insulation begins as a solid granule of polystyrene resin. The plastic granules are fed into an extruder, where they are melted and mixed with critical additives to form a viscous fluid. Next, a blowing agent is injected to enable the plastic product’s expansion. Under carefully controlled heat and pressure conditions, the plastic mixture is forced through a die into the desired shape. The rigid foam plastic is then trimmed to the final product dimensions and is usually recognized as boards.

This continuous process produces a closed-cell structure that looks like a mass of uniform bubbles with common walls between them. A continuous smooth skin on the top and bottom also forms.

The closed-cell structure of extruded polystyrene foam imparts excellent long-term strength and durability. Products are available in a range of compression strengths to suit varied application needs. Due to its inherent physical properties, this strength does not depend on the use of facers or laminates, which can sometimes be compromised during installation. However, extruded polystyrene foam faced-products are available to add extra strength when specified for a particular application. Extruded polystyrene plastic also comes in a wide variety of sizes, and up to a thickness of 102 mm (4 in.) to suit many applications.

XPS Energy Efficiency

Extruded polystyrene foam sheathing can have positive energy and air emission benefits when used in residential buildings.

Properly installed XPS foam can also improve a building’s energy efficiency by providing a complete layer of insulation on the wall. This reduces air movement through the wall that can rob energy. Insulation between studs does not necessarily offer complete insulation value because wood studs and other framing members are not insulated. This phenomenon is called thermal bridging and can dramatically decrease thermal performance of the building.

Since residential wood framing typically makes up about 25 percent of the wall area (taking into account window and door framing), a quarter of the wall is uninsulated when only cavity insulation is used. As such, extruded polystyrene foam sheathing can provide insulating value to the entire wall area. Aside from its inherent insulating performance, XPS foam sheathing, when properly installed and seams taped, can also greatly reduce air leakage through walls, which can improve energy efficiency and comfort.

An essential attribute for sustainable building products, especially insulation, is the ability to function properly over its useful life without physical property performance degradation. In fact, good long-term insulation performance is needed to correctly design a building’s heating and air-conditioning systems.

Extruded polystyrene foam can also have advantages due to its ability to assist with moisture management, resisting both water absorption and freeze/thaw cycles. When traditional insulation absorbs water, its thermal performance can be compromised over time.

In the next time, we will move on to the recycling and installation of XPS foam. Please keep focus on TOPOLO.

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