Utherm Roof BM on flat roofs: matching the facing to the waterproofing

List both facings in their specified order from the deck to the roof surface. Against each face, enter the material it will touch. At delivery, check the board designation against the section specified for that roof area.

In Unilin’s data sheet, the declared thermal conductivity of Roof BM varies with thickness. It is 0.027 W/(m·K) below 80 mm, 0.026 from 80 mm to under 120 mm, and 0.024 from 120 mm upwards. Use the applicable band for each thickness being assessed.

The 100 mm board has a declared resistance of 3.80 m²K/W and the 120 mm board 5.00 m²K/W. The extra 20 mm therefore adds 1.20 m²K/W of board resistance. Check on the section that the extra height fits beneath the parapet flashing and at plant kerbs.

The 1,200 × 600 mm board has four square edges. Set out the pipe penetration in relation to the joints in adjacent rows. Check the actual sleeve position before cutting so pieces can be laid with continuous support around the opening.

Mark the cut pieces on either side of the sleeve on the layout. If the second piece needs a mirror-image shape, cut it with the required facing orientation in mind. Turning over a finished offcut would swap faces B and M.

Find the permitted substrate, attachment method and application conditions for the first layer in the waterproofing documentation. For bonding, check the named adhesive, moisture and temperature limits and surface preparation. A heat-applied method needs to be expressly specified for the chosen system.

Before covering, check the facing for moisture, dirt and damage along handling routes. Identify the boundaries of the corner and perimeter wind zones on the fixing plan. The crew starting the next membrane roll should know where the fixing specification changes.

For Roof BM, the manufacturer declares at least 150 kPa in compression at 10% deformation. To check plant supports, give the designer the load, foot dimensions and load-distributing layers. How long the insulation will carry that load also matters.

Reaction to fire class F applies to the Roof BM product. Keep the required classification for the complete roof on file, with the deck, layers and attachment covered by the document. Check its scope again if the waterproofing is changed.

Split the take-off into the main roof area, parapet perimeter and service penetrations. Add the materials and labour for the first waterproofing layer to the board quantities. Two quotations can then be compared for the same area and number of details.

Record the selected BM thickness and the waterproofing reference on the order. If an alternative board is offered, compare the facings, the figures for that thickness and the jointing instructions. Issue any agreed change to both crews before unloading.

If a shift stops halfway along a row, mark the last inspected board on a sketch and note whether the first waterproofing layer is in place. At restart, compare the exposed face of the next board with the reference photograph and check the temporary protection at the open edge.