Planning a large industrial flat roof with IDELCO α-therm ROOF

Mark the edges of the structural deck, openings and drain levels. Overlay the board layout and identify items that penetrate the insulation. Both faces of the ROOF board have a gas-tight kraft paper and aluminium laminate. The connection between this surface and the adjoining layers depends on the specified roof system.

For λ = 0.022 W/(m·K), the manufacturer lists a declared thermal resistance of 4.50 m²K/W at 100 mm and 6.35 m²K/W at 140 mm. The gain of 1.85 m²K/W applies to the insulation layer. The roof U-value calculation also accounts for the other layers and the effect of fixings as applicable.

An extra 40 mm raises the top of the insulation by the same amount if the deck level stays fixed. Check waterproofing upstand heights at rooflight kerbs and the clearance below thresholds in section. Where an upstand has to be raised, include that work in the quantities.

Try both available sizes, 1200 × 600 mm and 1200 × 2400 mm, against a row of rooflights on the drawing. Compare the number of full boards and the width of the last strip at each opening. A larger board gives fewer field joints, but cutting yield depends on the actual rooflight spacing.

Boards come with square or rebated edges. Cutting a rebated board leaves a square edge along the cut. Mark which edges of an offcut still have the factory profile. The installer can then check whether it can be reused in the next row with the specified joint detail.

With mechanical fixing, loads from the covering pass through the fasteners into the deck. The fixing plan specifies fastener type and layout in the field, at edges and at corners. Using total roof area alone overlooks the differences in wind load between these zones.

For a bonded build-up, check the approved substrate, facing and adhesive for each bond in the system documentation. For a ballasted roof, the design should show ballast distribution and weight so the structural engineer can allow for the permanent load. Changing methods on site requires these assumptions to be checked again.

Declared compressive stress is at least 150 kPa at 10% deformation. This test value does not specify a permissible long-term bearing pressure beneath a plant foot. For an air-handling unit, the designer needs support reactions, foot areas and a detail showing how loads reach the structural members.

The manufacturer lists reaction-to-fire class F for the product itself. A separate B-s2,d0 result applies to the stated end-use on a steel deck. Compare the proposed build-up with the classification conditions before citing this result. The fire resistance of the roof assembly is a separate assessment.

One 1200 × 2400 mm board has a nominal area of 2.88 m². In the packing table for 140 mm boards, four boards give 11.52 m² per pack and four packs give 46.08 m² per pallet. These figures provide a check on the quotation before adding cutting waste.

Specify α-therm ROOF, dimensions, thickness and edge profile on the order. If the bill of quantities uses the older name I-ROOF, compare the project requirements with the current product sheet for the delivery. State pack quantities for each phase and choose storage locations within the permitted loading limits.

On a sample hall plan, mark an unobstructed rectangle and a strip around the air-handling unit. The first can be measured in rows of full boards. For the second, list the cut sizes and measure the plant base flashings separately. This lets the contractor price two different levels of labour for the same PIR thickness.