GREEN BUILDING SOLUTIONS……Extruded Polystyrene Sheathing (XPS).
The most common components of a building’s envelope perform is just as important as its structural design 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.
Extruded polystyrene (XPS) offers many benefits due to the way this product is manufactured.
It is energy-efficient, easy to install and lightweight, the specification of extruded polystyrene sheets allow the use of a single product to create a continuous layer of thermal and moisture protection on a building’s floors, walls and ceiling structures, thereby contributing to energy efficiency of a building.
How is Extruded Polystyrene Created:
Extruded polystyrene foam begins as solid granules 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 to produce the desired width and thickness, it then continues as one long length
down a roller conveyor to cool under ambient temperature.
The long length of cooled extruded polystyrene is then trimmed to the final product dimensions (additionally length and width shiplap edges can added to the extruded polystyrene XPS boards).
This continuous process produces the closed-cell structure with smooth top and bottom surfaces where required diamond embossed surfaces are also added to allow for better bonding to other product surfaces.
The closed-cell structure of extruded polystyrene (XPS) foam imparts excellent long-term strength and durability. XPS Products are available in a range of compressive 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 (XPS) foam faced-products are available to add extra strength when specified for a particular application. Extruded polystyrene can be manufactured in a wide variety of lengths, widths and thickness subject to the size of supplier’s extruders.
XPS Energy efficiency
Extruded polystyrene (XPS) foam sheathing can have positive energy and air emission benefits when used in residential buildings. A 2000 Franklin Associates’ study shows far more energy is saved over the 50-year life of a home properly using XPS foam insulation than is consumed by manufacturing the insulation.
Other studies, presented at the 2004 Earth Tech forum, show that after less than three years, more greenhouse gas emissions are avoided due to heating/cooling energy consumption than are emitted during the manufacture of extruded polystyrene foam insulating sheathing.
Properly installed extruded polystyrene (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 (XPS) foam sheathing can provide insulating value to the entire wall area. Aside from its inherent insulating performance, extruded polystyrene (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.
Reduce, reuse, recycle
Three strong environmental principles are to reduce, reuse, and recycle. Since extruded polystyrene (XPS) foam insulating sheathing can reduce energy loss in buildings, it can lower (i.e. reduce) the amount of energy (gas and electric) required to maintain comfortable living environments.
The more widespread the use of extruded polystyrene (XPS) foam insulating sheathing, the more profound its effect can be on reducing consumption of natural resources, such as coal, oil, and gas.
Polystyrene resin is a thermoplastic material, which means it can be melted and re-inserted (i.e. reused) into the manufacture of new extruded polystyrene (XPS) foam insulation. Extruded polystyrene manufacturing plants create virtually no scrap or waste materials because nearly 100 percent is recovered, ground up and re-pelletized for the production system (i.e. recycled). Some companies even seek outside sources of scrap polystyrene plastic resin to reuse.