SOPREMA EFYOS BLUE A where roof insulation thickness is limited

Before the insulation thickness is taken as a starting value for further works, the parapet section with the levels of all layers must be established. A view of the flat roof field alone does not show all the heights. When purchasing EFYOS BLUE A, this detail should be agreed first.

In EFYOS BLUE A the core is made of PIR, with aluminium facings 50 μm thick on both sides. The declared λD is 0.022 W/(m·K). For 100 mm, RD 4.50 m²K/W is given, while for 120 mm it is 5.45 m²K/W. The product reaches class CS(10/Y)120 and fire reaction E. The data sheet permits straight or milled edges, so the external format does not always correspond to the coverage area. SOPREMA PIR boards should here be assessed for the application range of flat roof insulation under waterproofing. When checking an order, the term “polyurethane boards” does not replace the full name EFYOS BLUE A. In EFYOS BLUE A, polyurethane foam of the PIR type forms the core, and the properties of the complete board also include its facings.

For an initial comparison of EFYOS BLUE A, let us assume a nominal resistance of the layer alone, R=4.00 m²K/W. With a lambda of 0.022 W/(m·K), the simple product R × λ gives a thickness of about 88.0 mm. For a comparative assumed lambda of 0.036, this would be 144.0 mm. The second lambda is an assumption of the example, not a description of the entire group of competing materials. The result shows a possible difference in space for the same resistance. The commercial variant must be selected from the EFYOS BLUE A documentation. The difference in millimetres alone does not remove the limitation, which is the height limit at the detailing.

In the example concerning EFYOS BLUE A, the figures describe only the specified part of the task. Their use makes sense together with a measurement that includes the height of the parapet above the intended roof covering surface. The property relevant to the comparison is the lambda of 0.022 W/(m·K). In this arrangement, the level of the covering must also be compared with the flashing drawing. Only then does the parapet section with the levels of all layers allow the result to be related to the actual section. The energy calculation should retain the same scope also when comparing with a different thickness of EFYOS BLUE A.

The first direction is to increase the board thickness. The second is to refine the joint at the roof perimeter. The scope of both measures depends on how important the termination of the insulation at the parapet is. In the EFYOS BLUE A variant, the cost of the entire surface should not be increased before the local constraint has been investigated. A pitfall would be to devote the entire available height to the insulation alone, even if the result for the main field looks favourable. The comparison is only complete when the schedule of thicknesses, edges and coverage areas also includes the differences caused by changing the variant.

The design should clearly specify a straight or tongued-and-grooved joint depending on the variant. In the description of EFYOS BLUE A, it is worth separating its geometry from the tightness of the other layers. The product surface is formed by a blue aluminium facing, but its presence does not automatically solve the entire detail. A record of the thickness and edge variant from the label is needed for verification. The next stage will be the waterproofing covering above the board, so the error should not be passed on to the installer of the next layer. It is worth noting at handover how the termination of the insulation at the parapet was executed and why this particular method was chosen.

The quotation for EFYOS BLUE A should relate to the completed task, not to a single favourable parameter. The calculation should include the schedule of thicknesses, edges and coverage areas. A separate cost may arise because support for the boards with a load-distribution layer is needed. It is also worth pricing the work at the detail described as the termination of the insulation at the parapet. The differences should be explained by the designer of the roof section, so that the saving does not result from removing a necessary layer. Polyurethane insulation compared in this way corresponds to the real effect that the insulation of a flat roof beneath the waterproofing is intended to achieve.

The selection can be regarded as orderly when it has been possible to accommodate the thermal layer and preserve a correct waterproofing termination. For EFYOS BLUE A, this means combining the material data with the solution for the perimeter and the other layers. The document to keep is the parapet section with the levels of all layers. It should be accompanied by a record of the thickness and edge variant from the label, so that a later renovation does not begin with guessing the product. There is no need to add a promise of a quick payback without a building balance. If the height limit at the flashing changes, it is necessary to return to the comparison instead of copying the earlier thickness. Polyurethane insulation has a specific purpose here: to accommodate the thermal layer and preserve a correct waterproofing termination.