ISO-ACO-02 — Roof — beneath the roof covering
1. Subject and scope of application
This specification sets out the technical requirements for quality, execution and acceptance for the build-up “Roof — beneath the roof covering”, in accordance with Isoflect construction detail ISO-ACO-02. Reflectiva Bronze/Silver between the counter-batten and the batten — installed from the bottom upwards, with a minimum of 50 cm left clear at the eaves and at the ridge.
The specification covers the supply and installation of the Isoflect products in the build-up: Reflectiva Silver, Reflectiva Bronze, Reflectiva Roof Pro and Reflectiva Roof Optim. It applies to new constructions and renovations where the design provides for this build-up, and is to be read together with the CAD detail and the technical data sheets of the products.
2. Build-up
Sequence of layers, as per the CAD detail: unheated attic → exterior.
| No. | Layer |
|---|---|
| 1 | Planed roof boarding 24 mm |
| 2 | Reflectiva Roof Pro or Roof Optim — anti-condensation membrane |
| 3 | Vertical batten 50 × 50 mm |
| 4 | Reflectiva Bronze — beneath the roof covering |
| 5 | Horizontal batten 30 × 50 mm, spacing 155 mm |
| 6 | Ceramic roof tile — beaver-tail (scale) tile 180 × 380 mm |
3. Materials and required characteristics
Reflectiva Silver
| Characteristic | Value | Standard |
|---|---|---|
| Build-up | Polyethylene air-bubble film of 110 g/m², with 24 µm pure aluminium film on both faces (7 µm aluminium + 17 µm lamination layer) | |
| Total thickness | 4 mm (±1) | EN 823 |
| Mass per unit area | 220 g/m² | EN 1849-2 |
| Roll dimensions | 1,20 m × 33,33 m — 40 m² | EN 1848-2 |
| Reflectivity of thermal radiation | 95–97 % | |
| Emissivity | 0,05 | prEN 15976 |
| Water vapour diffusion resistance, Sd | 190 m | EN ISO 12572 |
| Resistance to water penetration | Class W1 | EN 1928 |
| Tensile strength (longitudinal / transverse) | 63 / 48 N/50 mm | EN 12311-1 |
| Elongation (longitudinal / transverse) | 55 % / 43 % | EN 12311-1 |
| Flexibility at low temperatures | −40 °C, no cracks on either face | EN 1109 |
| Dimensional stability (longitudinal / transverse) | −1,8 % / −0,4 % | EN 1107-2 |
Reflectiva Bronze
| Characteristic | Value | Standard |
|---|---|---|
| Build-up | One face of pure aluminium, the other a polyethylene air-bubble film | |
| Total thickness | 3 mm | EN 823 |
| Mass per unit area | 125 g/m² | EN 1849-2 |
| Roll dimensions | 1,20 m × 33,33 m — 40 m² | EN 1848-2 |
| Emissivity | 0,05 | prEN 15976 |
| Water vapour diffusion resistance, Sd | 140 m | EN ISO 12572 |
| Water resistance | Class W | EN 1928 |
| Reaction to fire | Class F | SR EN 13501-1+A1:2010 |
Mechanical values (tensile strength, elongation, tear resistance) are not declared for this product.
Reflectiva Roof Pro
| Characteristic | Value | Standard |
|---|---|---|
| Build-up | Micro-perforated pure aluminium + microporous polypropylene film, heat-bonded, mesh-reinforced structure | |
| Roll dimensions | 1,50 m × 50 m — 75 m²; 17,5 kg | EN 1848-2 |
| Mass per unit area | 230 g/m² | EN 1849-2 |
| Reflectivity of thermal radiation | 95–97 % | |
| Emissivity (before / after ageing) | 0,05 / 0,05 | prEN 15976 |
| Water vapour diffusion resistance, Sd | 0,045 m (±0,015) | EN 12572 |
| Resistance to water penetration | Class W1, including after artificial ageing | EN 1928 / EN 13859-1, Annex C |
| Tensile strength (MD / CMD) | 350 / 225 N/50 mm | EN 12311-1 |
| Tensile strength after ageing (MD / CMD) | 330 / 175 N/50 mm | EN 13859-1, Annex C |
| Elongation (MD / CMD) | 30 % / 70 % | EN 12311-1 |
| Tear resistance | 200 / 200 N | EN 12310-1 |
| Dimensional stability | < 2 % | EN 1107-2 |
| Flexibility at low temperatures | −30 °C | EN 1109 |
| Service temperature range | −40 … +80 °C | |
| Reaction to fire | Class E | SR EN 13501-1 |
| Visible defects | No visible defects | EN 1850-2 |
| Estimated service life | 50 years |
Reflectiva Roof Optim
| Characteristic | Value | Standard |
|---|---|---|
| Build-up | 4 layers: outer micro-perforated aluminised foil + three layers of microporous polypropylene film; two integrated self-adhesive strips along the full length | |
| Roll dimensions | 1,50 m × 50 m — 75 m²; 12 kg | EN 1848-2 |
| Mass per unit area | 155 g/m² | EN 1849-2 |
| Emissivity (before / after ageing) | 0,18 / 0,18 | prEN 15976 |
| Water vapour diffusion resistance, Sd | 0,07 m (±0,02) | EN 12572 |
| Resistance to water penetration | Class W1, including after artificial ageing | EN 1928 / EN 13859-1, Annex C |
| Tensile strength (MD / CMD) | 330 / 230 N/50 mm; after ageing 280 / 195 | EN 12311-1 |
| Elongation (MD / CMD) | 40 % / 20 %; after ageing 30 % / 10 % | EN 12311-1 |
| Tear resistance | 130 / 140 N | EN 12310-1 |
| Dimensional stability | < 2 % | EN 1107-2 |
| Flexibility at low temperatures | −20 °C | EN 1109 |
| Service temperature range | −40 … +80 °C | |
| Reaction to fire | Class E | SR EN 13501-1 / EN ISO 11925-2 |
| Estimated service life | 30 years |
The declared values refer to the product, not to the build-up in which it is installed; the performance of the system is determined by a hygrothermal calculation for each case. The current revision of the technical data sheet shall always apply.
Materials in the build-up that are not Isoflect products (timber, boards, metal profiles, roof coverings, waterproofing, screeds, finishes) shall be specified by the designer, in accordance with the applicable product standards and the manufacturers' documentation.
4. Delivery, storage, handling
The products are delivered in their original, labelled packaging, accompanied by the quality documents and, where issued, the declaration of performance. On receipt, the product designation, the roll dimensions or the contents of the package, and the integrity of the packaging are checked.
The Reflectiva Silver and Reflectiva Bronze rolls are stored horizontally, on a clean and level surface, protected from direct solar radiation and from moisture.
The Reflectiva Roof Pro and Reflectiva Roof Optim rolls are stored horizontally, on a clean and level surface, protected from the sun.
The membranes are handled so that the aluminium faces are not perforated or damaged; damaged areas are repaired before the layer is closed.
5. Execution conditions and sequence
Execution begins only after the load-bearing structure has been completed and checked, and the installation surfaces are clean and dry. The layers are executed in the build-up order shown in detail ISO-ACO-02; each layer that is to be covered is checked before being covered. Isoflect products are installed in accordance with the technical data sheets in force.
Orientation of the aluminium faces: the aluminium is always oriented towards the adjacent air gap, as indicated in the build-up. A membrane bonded directly to a wall or ceiling is installed with the aluminium facing inwards, that is, likewise towards the air gap.
Reflectiva Roof Pro and Reflectiva Roof Optim: fixing is carried out with corrosion-resistant nails or flat-head staples. The strips overlap by approximately 10 cm, so that the integrated self-adhesive strips overlap one another rather than lying side by side. Direct exposure until covering is a maximum of 90 days. The membrane is not installed on surfaces with a temperature above 80 °C. On the roof, the membrane is installed horizontally, across the slope, starting from the eaves; the adhesive strip on the inner face is oriented downwards, towards the eaves, and the one on the aluminised face upwards, towards the ridge. Ventilation is provided above the membrane, through the counter-battens and battens — the ventilation layer is mandatory; no ventilation space is provided beneath the membrane.
Reflectiva Bronze or Silver is installed between the counter-batten and the batten, in strips parallel to the eaves, from the bottom upwards, progressing towards the ridge, with a ventilated space at the eaves and at the ridge. Reflectiva Bronze must be installed with the pure aluminium face upwards, towards the roof covering. Detail ISO-ACO-02 provides for a minimum of 50 cm clear at the eaves and at the ridge. Reflectiva Bronze is intended for unheated attics.
6. Checks during execution and at acceptance
On receipt of the materials, the following are checked: the designation and type of the products, in accordance with the design; the current revision of the technical data sheets; the roll dimensions and the contents of the packages; the integrity of the packaging and of the aluminium faces; the declarations of performance, for products that have them.
During execution, the following are checked:
- the orientation of the aluminium faces, in accordance with the detail, and the continuity of the reflective layer; the sealing of all joints, overlaps and junctions with Isoflect Power Tape, without creases, detachments or gaps;
- for roof membranes: overlaps of approximately 10 cm, with the self-adhesive strips overlapping and bonded; the fixing; the duration of direct exposure, a maximum of 90 days;
- the presence of the ventilation layer above the roof membrane;
- for Reflectiva Bronze / Silver: the orientation of Bronze with the aluminium facing upwards, and the clear ventilation spaces at the eaves and at the ridge.
Before each layer is covered (plasterboard, OSB, roof boarding, screed, roof covering), a record of concealed works shall be drawn up in accordance with the regulations in force. Acceptance upon completion of the works shall be based on the records of concealed works, the quality documents of the products and the visual inspection of the accessible layers.
7. Measurement and settlement
The Isoflect membranes (Reflectiva Silver, Reflectiva Bronze, Reflectiva Roof Pro and Reflectiva Roof Optim) shall be measured in m² of covered area, as developed, without separate inclusion of the overlaps; overlaps, fixings and technological losses are included in the unit price.
The other layers (structure, profiles, boards, roof coverings, waterproofing, screeds, finishes) shall be measured and settled in accordance with the relevant work chapters.
8. Reference documents
- Isoflect construction detail ISO-ACO-02 — PDF, DXF and IFC, from the library for designers.
- Technical data sheet Reflectiva Silver, revision 4, 13.09.2026.
- Declaration of performance Reflectiva Silver.
- Technical data sheet Reflectiva Bronze, revision 4, 13.09.2026.
- Declaration of performance Reflectiva Bronze.
- Technical data sheet Reflectiva Roof Pro, revision 4, 13.09.2026.
- Declaration of performance Reflectiva Roof Pro.
- Technical data sheet Reflectiva Roof Optim, revision 4, 13.09.2026.
- Declaration of performance Reflectiva Roof Optim.
- Test standards cited in the technical data sheets: EN 1107-2, EN 1109, EN 12310-1, EN 12311-1, EN 12572, EN 13859-1, EN 1848-2, EN 1849-2, EN 1850-2, EN 1928, EN 823, EN ISO 11925-2, EN ISO 12572, SR EN 13501-1, SR EN 13501-1+A1:2010, prEN 15976.