ISO-POD-04 — Reflective package beneath the attic floor
1. Subject and scope of application
This specification sets out the technical requirements for quality, execution and acceptance for the build-up “Reflective package beneath the attic floor”, in accordance with Isoflect construction detail ISO-POD-04. Plasterboard, Multistrat, double CD substructure and Gold beneath the joists, with no insulation between the joists.
The specification covers the supply and installation of the Isoflect products in the build-up: Reflectiva Gold, Reflectiva Multistrat and Isoflect Power Tape. 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: room → unheated attic.
| No. | Layer |
|---|---|
| 1 | Roof boarding 24 mm |
| 2 | Timber joists 50 × 150 mm, without insulation |
| 3 | Reflectiva Gold |
| 4 | Double framework of CD 60/27 profiles + air |
| 5 | Reflectiva Multistrat — aluminium facing outwards |
| 6 | Plasterboard 12,5 mm — room ceiling |
3. Materials and required characteristics
Reflectiva Gold
| Characteristic | Value | Standard |
|---|---|---|
| Build-up | Two pure aluminium faces; core of air-bubble film and expanded polyethylene | |
| Total thickness | 10 mm (±1) | EN 823 |
| Mass per unit area | 460 g/m² | EN 1850-2 |
| Roll dimensions | 1,20 m × 10 m — 12 m² | EN 1848-2 |
| Roll weight | 5,52 kg | |
| Reflectivity of thermal radiation | 95–97 % | |
| Emissivity | 0,05 | prEN 15976 |
| Water vapour diffusion resistance, Sd | 190 m | EN 13859-1 |
| Tensile strength (longitudinal / transverse) | 261 / 205 N/50 mm | EN 12311-1 |
| Elongation at break (longitudinal / transverse) | 21,6 % / 17,1 % | EN 12311-1 |
| Tear resistance (longitudinal / transverse) | 154 / 199 N | EN 12310-1 |
| Resistance to water penetration | Class W1 | EN 1928 / EN 13859-1 |
| Reaction to fire | Class F | SR EN 13501-1+A1:2010 |
| Volatile organic compounds (VOC) | None |
Reflectiva Multistrat
| Characteristic | Value | Standard |
|---|---|---|
| Build-up | Bubble film of 110 µm; on the bubble cap side, 24 µm pure aluminium film (7 µm aluminium + 17 µm lamination layer); on the opposite side, expanded polyethylene film | |
| Total thickness | 5 mm (±1) | EN 823 |
| Mass per unit area | 175 g/m² | EN 1850-2 |
| Roll dimensions | 1200 mm × 25 m (±3 %) — 30 m² | EN 1848-2 |
| Roll weight | 5,25 kg | |
| Reflectivity of thermal radiation | 95–97 % | |
| Emissivity | 0,05 | prEN 15976 |
| Water vapour diffusion resistance, Sd | 190 m | EN 13859-1 |
| Resistance to water penetration | Class W1 | EN 13859-1 |
| Reaction to fire | Class F | SR EN 13501-1+A1:2010 |
| Service temperature range | −40 … +80 °C | |
| Shelf life | 24 months from delivery |
Isoflect Power Tape
| Characteristic | Value | Standard |
|---|---|---|
| Width | 10 cm | |
| Roll length | 50 m | |
| Service temperature range | −60 … +140 °C | |
| Required for Floor Pro | One roll for each roll of Floor Pro (40 m²) |
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 Gold and Reflectiva Multistrat rolls are stored horizontally, on a clean and level surface, protected from direct solar radiation and from moisture.
The shelf life of Reflectiva Multistrat is 24 months from delivery.
Isoflect Power Tape is kept in its original packaging, in covered areas, protected from moisture and from direct solar radiation.
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-POD-04; 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 Gold is installed in the position indicated in the detail — in standard build-ups beneath the rafters, from the inside, over the bulk insulation. Joints and overlaps are hermetically sealed with Isoflect Power Tape, to ensure the continuity of the radiant barrier and of the vapour barrier.
Reflectiva Multistrat is installed in the position and with the orientation indicated in the detail. Where OSB is installed over the insulation between the rafters, the orientation is reversed: aluminium facing inwards. All joints are hermetically sealed with Isoflect Power Tape.
CD 60/27 profiles are installed with the 60 mm back facing the plasterboard. The air layer between the reflective membranes remains closed and continuous over the entire surface, at the thickness shown in the detail; the membrane joints on both faces of the air layer are sealed before closing.
Isoflect Power Tape is applied on a clean, dry and dust-free surface, pressing firmly along the entire length of the joint. Membrane overlaps are covered completely, so that the vapour barrier is continuous; perimeter junctions, penetrations and openings are sealed with the same tape.
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;
- the continuity and closure of the air layer, at the thickness shown in the detail.
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 Gold and Reflectiva Multistrat) 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.
Isoflect Power Tape is included in the unit price of the sealed membrane or is measured separately, in rolls of 50 m, as established in the bills of quantities.
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-POD-04 — PDF, DXF and IFC, from the library for designers.
- Technical data sheet Reflectiva Gold, revision 5, 11.10.2026.
- Technical data sheet Reflectiva Multistrat, revision 4, 13.09.2026.
- Declaration of performance Reflectiva Multistrat.
- Technical data sheet Isoflect Power Tape, revision 4, 13.09.2026.
- Test standards cited in the technical data sheets: EN 12310-1, EN 12311-1, EN 13859-1, EN 1848-2, EN 1850-2, EN 1928, EN 823, SR EN 13501-1+A1:2010, prEN 15976.