The benefits of coated VIP insulation
Vacuum Insulated Panels, or VIP’s, have been used in warm and inverted roof construction for a while now, they even have their own Wikipedia page. Despite being sold to the roofing market for nearly 10 years they remain a product not all contractors will have worked with, primarily because they are much more expensive than conventional roof insulation.
The high cost is primarily due to the slow production speed; each panel is formed individually from dried silica sand compressed into a square or rectangle before being wrapped in an aluminium foil. The air is then sucked out of the foil wrapped block and the foil sealed to create a vacuum. The vacuum is what creates the very high efficiency, enabling the insulation thickness to be significantly reduced.
There are a couple of challenges with a VIP insulation, firstly you cannot cut the panel like a traditional PIR or XPS. PIR or XPS is used as an infill at perimeters, penetrations etc so installing VIP with PIR or XPS infill is like a jigsaw puzzle. The other challenge is that you cannot puncture the VIP for the same reason you cannot cut it – you eliminate the vacuum that creates the super efficiency in the first place.
There are currently a number of methods used to reduce the potential to puncture the aluminium foil:
• Laminated rubber crumb – this only protects the top and bottom of the VIP, leaving the sides unprotected from potential damage.
• Encapsulating in PIR – a higher than normal density PIR encapsulates the VIP. This provides protection on all sides of the VIP but increases the thickness of the VIP significantly. This method is only suitable for warm roof applications and none of the products are currently BBA Certified.
• Elastomeric Coating – the VIP is coated in a waterproof elastomeric coating. This method protects all sides of the VIP and is much thinner than PIR encapsulation. These VIP’s are widely used in inverted roof applications and are BBA Certified. In fact, they remain the only BBA certified VIP products sold in the UK.
When using any form of VIP insulation, the roofing contractor is facing a large purchase bill from the supplier. The roofing contractor can make a good margin on the VIP insulation but the contractor needs to ensure that they allow more time for installation and that the installers know the VIP has to be handled with care. Damaging a few VIP panels during installation could hurt the bottom line of the project profits rather than adding to it; but the high cost is also a good way to get the main contractor to protect the roof from other trades!
Next month: ADL 2021, what’s changed?