4 minute read
Insulation conversation by Theresa Braunsch, SPECTrum Building Energy
Insulation Conversation
More than 120 Members registered for a webinar on insulation products in April, presented by Theresa Braunsch from SPECTrum Building Energy.
Here, Theresa Braunsch answers six questions on the topic, posed by DMN Members.
Q. Insulation in flood-prone buildings: PUR or PIR?
A. Rigid, closed-cell insulation should be used in flood prone areas. XPS is certainly the most suitable closed-cell insulation for flood-zoned areas and will not absorb moisture, contrary to
EPS. Most insulation materials will become ineffective and damaged when submerged in water for a long period of time. PIR can handle small amounts of water but can dissolve when sunk in water. It is flame- and smoke-resistant, it slows the spread of flames and reduces smoke emitted in case of fire. PUR insulation does not have the same fire-resistant properties.
We should emphasise how important it is to take a holistic approach to architecture in flood prone areas, educate and seek expert advice.
Floor levels should be elevated above the flood level and wall cavities accessible if possible, where insulation can be easily replaced or excessed and dried after flooding. Waterproofing membranes should be installed and act as water barriers.
Manufacturer’s specifications, product performance, what environment is it suitable for, warranties and test reports should confirm the suitability of specific products.
Q. Wood below floor screeds? Could you tell us more about managing termite risk?
A. Referring to Wood Fibre below screed.
Wood Fibre under screed insulation, which is a higher density insulation, must be managed in similar ways to any other under-screed insulation, with a termite membrane. The advantage of this insulation being natural, without VOC, means it has not been chemically treated, therefore could be susceptible to termites as many construction products are. HomeGuard has a range of environmentally-friendly termite protection products, which can be handled without harm to humans and are highly effective. Soil testing will determine whether an area is prone to termites and if it is the case, regular testings, post construction, should be conducted to eliminate the risk.
Q. How does wood fibre (Gutex) compare, performance-wise, with straw panels (Durra panels – Australian made)?
A. Both insulation manufacturers offer a wide range of products suitable for different applications, which makes it difficult to compare. The Gutex
Range has around 20 products which have been tested to European standards and Australian building surveyors have the choice of accepting or rejecting its application. Most Gutex products have a thermal conductivity of 0.04 W/mK.
Compressive strength can range from 50 kPa to 200kPa. Wood fibre is a very versatile product.
Durra panels can be applied in walls and roofs.
The panels have great fire resistance and acoustic properties. The conductivity of the natural product is 0.081W/mK, which is higher than Woodfibre and will require a thicker panel to achieve the same insulation R- value.
Durra products have thermal mass properties.
As Durra panels are manufactured locally, transport is not contributing to embodied energy. Both products are biodegradable and
The insulation integrity will be maintained when a suitable product is selected and installed according to manufacturer’s specifications, according to Theresa.
recyclable, making it a sustainable solution. The choice between Gutex and Durra Panels should be determined according to project-specific design intent and construction systems.
Q. How do we know that the insulation’s integrity is maintained when installed? Should a professional install insulation?
A. The insulation integrity will be maintained when a suitable product is selected and installed according to manufacturer’s specifications. The products will perform well when sufficient ventilation and humidity control will reduce the risk of condensation and avoid damage due to moisture. Insulation should be installed avoiding gaps (due to services and other penetrations). Air tightness will maintain the performance by minimising heat convection (air circulation). The products should be able to dry when exposed to moisture and be dimensionally stable (not slump). An external vapour-permeable but water-resistant membrane will protect the insulation from water damage.
Q. KoolTherm advertises itself as a Phenolic insulation and with better R-Values than PIR. How is this different from PIR?
A. Kooltherm insulation by Kingspan is made by mixing phenolic resin with a blowing agent. It is a close-cell rigid insulation like PIR and PUR. The R-Value is slightly better than PIR insulation due to the lower conductivity of the material, which is 0.018 – 0.023
W/mK. Kingspan is referring to its blowing agent as non-toxic and assuring no CFC or HCFC is being used in its manufacturing process, which are contributors to ozone depletion. Kooltherm brochures point out that the product has zero Ozone Depletion Potential as well as low Global Warming Potential. No information is published about the type of fire retarder used for Kooltherm insulation. PIR board is made from MDI (Methylene Diphenyl Diisocyanate), polyol and Pentane as the blowing agent (no ODP). Most PIR boards use TCPP (Tris Chloroisopropyl Phosphate) fire retardant which is toxic and can be harmful to humans.
Q. What insulation product would you recommend for the small ceiling space under a Bondek deck slab when there is a bathroom underneath.
This would be in a cold climate zone.
A. Bathroom areas produce a lot of vapour, the insulation should be vapour permeable and able to absorb moisture and dry without damage (Rockwool or Wood Fibre). If possible, have a thin insulation layer under the Bondek metal as well to prevent condensation on the metal surface which would then drop onto the insulation layer. It’s best if the cavity between ceiling and roof can be ventilated as well. Air tightness layer between the insulation and plaster board will discourage the vapour to transfer easily into the roof cavity. Extraction fans connected to the exterior will dehumidify the space reducing relative humidity. Windows should be opened when showering.
