CAVITY PHENOLIC INSULATION BOARDS

Cavity wall phenolic board is a superior performance insulation with a thermoset phenolic core designed to be used either in partial-fill or full fill cavity wall insulation systems. In fact, the board offers the best U-values whilst maintaining a residual cavity, offering protection from wind driven rain. While this closed cell foam offers the highest R-value of 0.018W/mK, it does tend to be more expensive. On other hand this PF (Phenolic Foam) offers the thinnest insulation boards for a given specific U-value. Cavity phenolic boards are often associated with the Kingspan brand. Not without a reason. Kingspan, an Irish company, has been producing and selling Kooltherm in Europe since 1992. As the first, Kingspan invented phenolic core insulation. Today, being the best in its class, it is used everywhere where standard insulation thicknesses are simply too thick. Kingspan cavity phenolic board insulation appears under the name Kooltherm K108 and K106. The most common thicknesses are: 50mm, 75mm, 90mm and 100mm. While Kingspan offers only Kooltherm K-range, Xtratherm seems to offer a bit more. Xtratherm has a product called Xtratherm SR/CW. This top-class, square edge board has an excellent Euroclass B-s1 and d0 Fire Classification. Using SR/CW allows the residual cavity to be maintained, providing an effective method of preventing moisture ingression. Both brands are supplied at 455mm wide, 1200mm long to allow easy installation between standard vertical wall tie spacings and minimum on-site off-cuts and wastage. Phenolic cavity insulation boards should be installed together with the cavity closer. It is manufactured from a uPVC material allowing it to be provided in a strip format and is designed to maintain continuous insulation around window and door openings in masonry cavity walls. Being much improved thermal resistance phenolic cavity wall insulation, boards can be covered under the government’s Green Homes Grant. To ensure compliance, it is a good idea to use phenolic insulation boards to target an external wall U-value of 0.16 W/m²K for properties in England and Wales and 0.15 W/m²K in Scotland. Further installation information may be found in our cavity board datasheet section.

PHENOLIC CAVITY INSULATION COSTS

As of 2022, 100mm Xtratherm SR/CW phenolic cavity insulation will cost £46.80 per m2. On other hand using thinner 50mm Kingspan K108 Kooltherm material, you will cut the costs to £24.33 per m2. In fact, Kingspan seems to offer 0.002W/mK better R-value then competitive brand Xtrathem. Prices on the most popular 100mm board seems to be at the same level costing £46.93 per m2. Comparing all the thicknesses prices it can be concluded that 50mm thickness is the best value for money cavity phenolic insulation: 50mm - £22.53/m2 | 60mm - £28.38/m2 | 75mm - £35.83/m2  | 100mm - £46.93/m2 .
While the cavity phenolic insulation boards themselves are more expensive than lower-performing PIR materials, they can enable the desired U-value to be reached using thinner insulation and thus creating a thinner overall external wall construction. This can have a significant impact on other areas of the construction, such as the size and cost of foundations. The thinner cavity for the phenolic insulation specification would allow a narrower foundation of 650mm compared with 900mm for the glass mineral fibre.

PHENOLIC CAVITY BOARDS VS  GLASS MINERAL WOOL

It has been proved that while the cost of the glass mineral fibre insulation itself was less than the phenolic insulation, the increased cavity width with the glass mineral fibre specification raised the cost of all accessories. In addition to more extensive foundations and associated groundworks, the need for wider cavities and thicker walls also led to an increase in the external wall areas. The analysis showed that the overall cost for the large and small detached houses with the phenolic insulation specification and 600mm foundation was actually less than that of the glass mineral fibre specification with a 900mm foundation. In addition to these cost benefits, the reduced construction thickness of the phenolic insulation specification may also help to increase natural light levels within the space. Research has shown that by installing phenolic insulation over glass mineral fibre alternatives, external wall and window reveal depths can be reduced. This can help to improve daylight levels within a room. The research looked at a range of facade arrangements and found that the percentage improvement in the average daylight factor when using the phenolic construction over glass mineral fibre ranged between 10.6% and 63.2%. This can provide a healthier space for occupants and may make them more attractive and saleable to potential buyers.

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