XPS (the extruded rigid polystyrene foam) is very good insulation material. Its specific physical characteristics meet insulation material property needs. It insulates and protects buildings from extreme temperatures and moisture conditions. Not only the very good heat insulation and moisture resistance but also the good elasticity, high compressive strength and flame resistance have turned XPS to a preferred choice in construction sites since more than 50 years. Finally, XPS is light weight so it is easy to handle, fabricate and install.
INSUboards are made from Polystyrene raw material. It doesnt have a melting point. It starts to soften and shrink at 100 deg celcius, so the continous safe temp is 75 deg cel. They melt at even higher temperatures. If the melted mass gets further heated, ignitable decomposition gases are created at about 350°C. Without a flame source, temperatures above 450 to 500°C lead to the ignition of the decomposition products. Up to these temperatures, it is not self-ignitable.
INSUboards are made flame retardant to meet building and fire safety codes by adding suitable FR additive, which delays the process of burning and resists propagation of flames. When exposed to a small flame, the FR XPS will melt at the point of contact. If the contact with the external flame stops, it self extinguishes without further burning or smouldering.
The effects of combustion from XPS are not more acutely toxic than the effects of combustion from common building materials such as wood.
Due to its low water absorption XPS needs no measures to prevent it from water. But in flat roof application for example, protection from solar radiation is required. Exposure to direct UV radiation cause surface irregularities and discolouration., In practice, XPS therefore has to be covered with coatings, protective layers, laminations, etc. to protect from long-term radiation exposure and also wind forces
The water resistance property of INSUboard is very excellent ie the amount of water absorbed by the boards is negligible as compared to many other insulation materials, and the properties are not affected by water contact. It is for this reason they are used in over deck insulation applications alongwith water proofing systems. However, if only boards are used, the water may flow from the sides or edges or through the joints of boards. Hence it is important that the water does not stagnate on the system and proper slope has to be provided to ensure proper drainage.
Thermocole was the brand name of one company for EPS(Expanded Polystyrene). EPS is manufactured by batch process and the foam beads are fused together using steam and pressure to manufacture blocks and sheets of desired thicknesses are cut from these blocks. INSUboard is XPS (Extruded Polystyrene), manufactured by continous extrusion process wherein the beads are melted and the homogeneous molten mass is foamed using blowing gas and sheets are extruded. Thus we get closed cell structure, with improved mechanical properties and water resistance as compared to EPS.
In Over Deck applications, where XPS boards are used on the roof or terraces, the boards are laid adjacent to each other and held in position using adhesive tape. Normally, they are further covered with screed and tiles. In Under Deck applications, the boards are fixed below the roof or ceiling of the building. This can be done by suspending the boards using the regular frame structure as is done in false ceiling applications. Boards can also be nailed directly to the ceiling and later on covered with putty & paint. In External & Internal Wall insulation applications, the boards are fixed to walls using adhesive modified mortar and plastic nails. Plastic net or glassfiber mesh is fixed to the boards using thin coat of adhesive modified cement and further coated with cement mortar or plaster or stucco. In Foundation applications, the boards are placed on the floor adjacent to each other with no gaps, held in position using adhesive tape and covered with plastic sheet(to prevent damage) before the final screeding.