Polyisocyanurate or Mineral Wool Insulation? Ensuring a safe and efficient means of access should be a prioroty for architects. With such a wide variety of roof hatch types it may seem daunting at first to know what you need. Whether it is for just for maintenance or to install equipment into or out of the building. Other common applications for roof hatches include factories, office buildings, shopping centres, and non-residential buildings. All of which may require access to the roof area.
All roof hatches should be specified as thermally broken and insulated. Surespan roof hatches are manufactutred with a 50mm thermal break as standard. This ensures optimum performance and allows a high level of insulation.
A vast majority of access hatch manufacturers all state different figures when insulation and U-values are concerned. Regardless of this, the majority use a form of insulation called Polyisocyanurate, often referred to as PIR, polyiso, or ISO. PIR is a rigid thermoset plastic which offers great versatility and performance enabling it to be used for a wide variety of products.
What is wrong with PIR?
PIR insulation can have one major drawback, if the product ignites or catches fire, it can release the highly toxic gas, hydrogen cyanide. A number of victims during the recent Grenfell Tower were reported to have been subjected to toxic inhalation of these gases which can be attributed to some of the insulation used within the cladding. A chemistry and fire science professor from University of Central Lancashire said “…every flat would have its own source of PIR foam, which would have produced enough hydrogen cyanide to kill all the people in that flat”
PIR is often stated as Fire retardant or containing fire retardants however more often than not these refer to “Small scale tests” and may not reflect all hazards.
A study carried out by University of Central Lancashire found that PIR was the most toxic form of insulation. Other forms tested included the following materials: polystyrene, phenolic, polyurethane to Polyisocyanurate foam (most toxic). Whereas two of the materials tested, stone wool and glass wool failed to ignite and gave consistently low yields of all of the toxic products.
What is Non-combustible Mineral Wool Insulation?
Mineral wool insulation is NO COST alternative to our standard Polyisocyanurate and is becoming increasingly popular in specifications. Manufactured from 100% Natural and recyclable materials it not only is fire retardant but good for the environment too. In order to achieve European Reaction to Fire Classification of A1 – non-combustible. Stone wool is made from volcanic rock and achieves a European Reaction to Fire Classification of A1 – non-combustible.
The Prime Minister recently received a letter by the Mineral Wool Manufacturers Association urging the Government to consider taking important regulatory steps to improve fire safety in High-rise and high risk buildings such as schools, hospitals and care homes. One of these important steps was to specify Non-combustible cladding and insulation.
A recent report issued by Dame Judith Hackitt report highlighted the key issues with current Building Regulations and what should be advised in future. One of the key points the report highlighted was the use of combustible materials within the building process.