Choosing IKO enertherm MG thickness beneath a synthetic roof membrane

A roof section together with a confirmed membrane fixing method is essential — a view of the flat field alone does not show all heights. Before purchasing IKO enertherm MG, this part must be agreed before the thickness is adopted as an assumption for further works.

The core of IKO enertherm MG is PIR foam, while the facing on both sides is a perforated, coated glass fleece. The λD value is 0,026 W/(m·K) for thicknesses below 120 mm and 0,025 W/(m·K) from 120 mm. The RD of a 100 mm board is 3,80 m²K/W, whereas for 120 mm it is 4,80 m²K/W. The declared compressive strength is at least 150 kPa, and the reaction to fire is E. The manufacturer specifies use under synthetic membranes. IKO PIR boards should here be assessed for the application range that is a flat roof under a synthetic membrane. When checking an order, the term “polyurethane boards” does not replace the full name IKO enertherm MG. The properties of the complete board also include its facings, not only the PIR foam core.

When choosing IKO enertherm MG beneath a membrane, start with the requirements for the coated fleece and the waterproofing. To compare the depth needed by compatible materials, assume a resistance for the insulation layer alone of R = 4.00 m²K/W. Multiplying by λ = 0.026 W/(m·K) gives about 104.0 mm. The same R would require 144.0 mm at a hypothetical λ of 0.036. That is not a declared value for another product. Check the selected thickness against the MG documentation and confirm that the board is compatible with the waterproofing layer.

In the example concerning IKO enertherm MG, the figures describe only the indicated part of the task. Their use makes sense together with a measurement that covers the insulation thickness and the condition of the surface before the covering is installed. The property relevant to the comparison is the lambda of 0.026 below 120 mm and 0.025 from 120 mm. In this arrangement, the compatibility of the covering layer with the coated fleece must also be confirmed. Only then does the roof section with a confirmed method of fixing the membrane allow the result to be related to the actual section. The energy calculation should retain the same scope also when comparing with another thickness of IKO enertherm MG.

The first direction is selecting the MG thickness for the required resistance and the chosen covering. The second is a reassessment of the whole system after a different facing is proposed. The scope of both actions depends on how important the connection of the membrane to the surface of the boards in the fleece is. In the variant with IKO enertherm MG, the cost of the entire surface should not be increased before the local constraint has been identified. A trap would be to attribute to the MG board the lambda of 0.022 proper to another variant, even if the result for the main field looks favourable. The comparison is closed only when the MG description covering thickness, format and method of membrane work also includes the differences caused by a change of variant.

The design should clearly specify a simple butt joint of the boards under a continuous covering layer. In the description of IKO enertherm MG, it is worth separating its geometry from the tightness of the other layers. The product surface is formed by a perforated, coated glass fleece, but its presence does not automatically resolve the entire detail. What is needed for checking is a record of the MG designation and the condition of the fleece before covering. The next stage will be the synthetic membrane covering in the agreed installation, so the error should not be shifted onto the installer of the next layer. It is worth noting at acceptance how the connection of the membrane to the surface of the boards in the fleece was made and why this method was chosen.

The quotation for IKO enertherm MG should relate to the completed task, not to a single favourable parameter. The calculation should include the MG description covering thickness, format and method of membrane work. A separate cost may arise from the need for support with protection against point loading. It is also worth pricing the work at the detail described as the connection of the membrane to the surface of the boards in the fleece. The differences should be explained by the roof designer together with the specific synthetic membrane, 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 flat roof under a synthetic membrane is to achieve.

The selection can be regarded as orderly when both the thickness and a compatible method of connection to the membrane have been chosen. For IKO enertherm MG this means combining the material data with the solution for the perimeter and the other layers. The document to be kept is the roof section with a confirmed method of fixing the membrane. It should be accompanied by a record of the MG designation and the condition of the fleece before covering, 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 set of requirements for the coated fleece and the waterproofing changes, it is necessary to return to the comparison instead of copying the earlier thickness. Polyurethane insulation has a specific purpose here: to select the thickness and a compatible method of connection to the membrane.