The largest volume of rigid PIR boards is produced in sheet form. These are manufactured in double conveyor machines known as laminators. The foam is heated to a controlled thickness and pushed upwards into the envelop. The resulting faced sheet products are used extensively for construction applications. The layered construction of these rigid PIR boards ensures high thermal conductivity and high fire resistance. The following paragraphs discuss different features of PIR boards.
Thermal conductivity
Thermal conductivity of PIR boards is low. This property of PIR boards makes it a good choice for flat roof systems. The boards’ rigidity and flatness make them an ideal choice for synthetic membranes. Thermal resistance and R-value are high because more than 95% of PIR consists of closed cells. These characteristics allow them to maintain their parameters over a long period of time. Here are some of the benefits of PIR board insulation.
The material used for PIR insulation is typically composed of polyisocyanurate. This polymer has a relatively high molecular structure composed of OH groups and NCO groups. As a result, it’s very stiff compared to polyurethanes. Additionally, the OH groups in polyurethane balance out the NCO groups in polyisocyanurate. Consequently, thermal and chemical stability are important in some applications. Thermal and chemical stability are important properties when choosing PIR insulation, which is why some manufacturers offer a variety of products with different densities and indices.
Among the advantages of PIR insulation boards is their excellent resistance to air and water. These boards are suitable for applications like pitched roofs and cavity systems. The panels are often lined with gas-tight aluminium multilayer facings. They also provide excellent thermal insulation in low-temperature environments. A further advantage is that the RF6 Thermal Insulation Boards have a high specific heat capacity and temperature stability. These properties are essential for an effective and long-lasting thermal insulation system.
Another advantage of PIR thermal insulation boards is their lightweight nature. It is only half the thickness of mineral-based insulation and doubles the U-Value! Additionally, PIR thermal insulation boards are easier to handle and install than rock wool and mineral insulation. And because they are lightweight, they are easier to handle and fit into tight spaces. The weight of the PIR boards is also significantly reduced when compared to the weight and thickness of mineral-based and rockwool insulations.
Facer material
PIR boards have been used in thermal insulation applications for more than a century, but the use of new facer materials has allowed the technology to improve energy efficiency. This study examines the effect of facer material on the performance of PIR boards. This research was done in accordance with the ASTM C1498 standard and involves a test of three specimens with a 100 mm x 100 mm thickness. The measurements were carried out in climatic chambers at a constant 23 degC and desired relative humidity set points.
The facer material on PIR boards was characterized at the Building Science Centre of Excellence at BCIT. Its thermal properties include thermal conductivity, hygrothermal properties, sorption isotherm, vapor permeability, water absorption coefficient, and density. The next sections discuss the material characterization, simulation setup, and results. The study found that polymer-bonded glass fiber mats are suitable for PIR applications, as they exhibit a high level of insulative properties.
Expanded Polystyrene, or EPS, is the most inexpensive thermal board, but it is less effective as an insulator. Its R-value, or thermal resistance, is lower than that of other materials. However, EPS has numerous advantages: it is lightweight, has high compression strength, and does not attract vermin. EPS is also absorbent, so manufacturers add a facer material to increase the R-value.
Another common PIR foam board is 200. Similar to foam boards 100, it comprises a single outer portion 206 of a foam core 202. The foam core 202 can contain a polyol-isocyanate composition. The medial portion 204 may extend along the opposite edge of the foam core 202. This medial portion comprises between 75 and 90 percent of the foam core 202 thickness.
Moisture absorption
The hygrothermal properties of PIR insulation are measured in a laboratory and are extrapolated to other thicknesses based on the measured values. The hygrothermal properties of a PIR board are described in the following sections. These properties include thermal conductivity, moisture absorption coefficient, and density. For example, a PIR board with a facer of aluminum is less porous than a PIR with no facer.
The relative moisture content of three PIR boards at different relative humidities are reported in Table 5. The values are based on the water vapor permeability of the specimens measured in the same chamber, but at different temperatures. Generally, the higher the relative humidity, the greater the hygrothermal value of the board. Nevertheless, the results are only indicative of the actual moisture absorption. This study shows that the relative humidity of PIR boards varies greatly compared to other materials.
As a structural element, insulation is essential to prevent damage caused by both moisture and temperature. PIR boards are a good option for thermal insulation since their low water absorption and moisture resistance make them an ideal choice for floors. They are easy to install, durable, and lightweight, and can be used for many different applications. The materials can be combined in various combinations for optimal thermal insulation of floors and terraces. The advantages of PIR insulation are numerous:
Despite the hygrothermal properties of PIR boards, they must be protected by a waterproof layer. In addition to their ability to retain their shape, PIR insulation boards also have a low flammability. Further, they can be used for roofing applications, and they do not itch like other materials. This makes them ideal for interior and exterior insulation. So, if you’re planning to install PIR insulation boards on your home or office, make sure you buy one that features these attributes.
Fire resistance
PIR is a type of thermoset polymer, which is a combination of polyols and isocyanates. When heated, these materials undergo a cross-linking chemical reaction, resulting in a rigid, robust material. Thermoplastic materials, by contrast, are made from polymers that soften on heating and become liquids. The chemical reaction between the liquid polyol and the isocyanates causes a tacky, wet foam, which then hardens during the manufacturing process. PIR panels are made with steel faces and a PIR core, and have excellent structural and fire performance.
To investigate the impact of the OC content on fire resistance, we ran a series of experiments. For PIR panels, the HRR was measured for 10 min. For stone wool panels, it was 20 min, and for a PIR board, it was 22 min. After twenty minutes, the OC content diverged from the HRR curve. This is consistent with the lower limit of the HRR measured with stone wool panels. The lower limit represents the HRR correction for differences in the amount of oxygen present in the fire.
Using the same method, we compared the CO2 content of wooden cribs with and without PIR panels. While the PIR panel with wooden cribs had a slower fire growth, the stone wool crib had a higher CO2 concentration. Eight minutes after the fire started, black smoke appeared in the doorway. This smoke quickly thickened, and by 11 min, the fire had already risen to the upper portion of the wooden crib. As the fire grew, flames appeared in the smoke.
The results of the tests suggest that the wood crib and PIR panel contribute to higher temperatures. The wooden cribs were designed to represent a higher fire load than the PIR enclosure, which was 400 MJ m-2 for safety reasons. In the study, the wooden crib did not increase the fire output by much. Moreover, the fire output was only increased by 300 kW for three minutes with the PIR enclosure. The results show that the PIR panels are capable of withstanding the high temperatures of the fire.
Application
Among the many applications of PIR boards, wall sheathing is the most widely used. This type of insulation provides the highest R-value and thermal resistance. Foil-faced PIR is particularly suitable for masonry cavity wall construction. The reflective surface of the board provides protection from mechanical damage and is an effective vapor barrier. The following are some of the benefits of PIR insulation. All the benefits listed here are available in different versions.
The thermal properties of PIR insulation were measured in a laboratory using samples of different thicknesses. The hygrothermal properties were measured for a thickness of 12.7 mm (0.5 in) and another one of 38.1 mm (1.5 in) and extrapolated to other thicknesses. The density of PIR is calculated based on its physical dimensions and oven-dry mass measurements. The results are then compared with the values obtained for conventional insulations.
A comparison between the two types of PIR thermal insulation facings revealed that the former had an even greater impact on the rate of heat transfer than the latter. The study used an aluminum foil-faced PIR as an example. The same tests were performed with PIR boards that did not have aluminum foil facings. The heat flow through the connection was less than 0.001 W. This was in line with previous estimates and could have no effect on the heat loss of the building.
Thermal insulation panels with composite faces have the advantage of high thermal resistance. Their composite faces protect them from moisture, making them rot-proof and humidity-resistant. PIR boards with aluminized facings are less expensive to purchase than those without. Despite their higher cost, PIR insulation can be installed with minimal additional load on supporting structures. Further, they reduce transportation costs. So, when it comes to thermal insulation, PIR is a great choice.