The trafficable roof, used where the roof is a terrace. It matches the non-trafficable roof thermally at U 0.21 W/m²K and carries the additional mass of the walking surface at 130 kg/m², still 73% below the traditional equivalent.
D.09
Trafficable roof / terrace
Cubierta transitable / terraza
570 mm
Total thickness · Revision 01 · 2026-08
D.09
Trafficable roof / terrace
SCALE 1:10
Dashed layers sit inside the joist depth, not in addition to it. Keyboard navigable with the arrow keys; the same data is published as a table in the layer schedule below.
Photographs
1 / 10
Layer schedule
| Layer | Material | Thickness | λ | Function |
|---|---|---|---|---|
| 1 Paving | Paving | 10 mm | — | Walking surface The section sheet names this layer "Pavimento" at 10 mm and does not say what it is made of. D.07's equivalent is a ceramic tile, from the engineering annex; this one is not in that annex, so no material is stated here. |
| 2 Adhesive | Adhesive | 5 mm | — | Bonds the paving Named "Pegamento" at 5 mm on the section sheet, with no material stated. |
| 3 Geotextile | Geotextile | 2 mm | — | Between the paving bed and the waterproofing The Spanish label is the section sheet's own spelling, "Geotextile". It is not translated here — see docs/OPEN-ITEMS.md item 3. |
| 4 Self-protected bituminous membrane | Bituminous waterproofing membrane | 5 mm | — | Waterproofing |
| 5 Lightweight concrete to falls | Lightweight concrete | 120 mm | — | Forms the falls Laid to falls: 120 mm at the high point, 50 mm at the low point. The 570 mm total is taken at the high point. The section sheet gives the density as 500 kg/m³. |
| 6 OSB board | Oriented strand board | 15 mm | — | Substrate for the screed |
| 7 XPS | Extruded polystyrene | 50 mm | — | Thermal insulation |
| 8 OSB board | Oriented strand board | 15 mm | — | Structural decking |
| 9 Void within the joist depth within joist depth | Air | 200 mm | — | Services zone Approximately 200 mm: the 300 mm joist depth less the 100 mm of glass wool. |
| 10 Glass wool within joist depth | Glass mineral wool | 100 mm | — | Thermal and acoustic insulation |
| 11 Steel lattice joist | Prefabricated cold-formed steel lattice joist | 300 mm | — | Structure — the joist depth contains layers 9 and 10 The section sheet states 300 mm and gives no range of depths, where D.08's sheet gives four. The 570 mm total is the drawn one. |
| 12 Ceiling void | Air | 20 mm | — | Ceiling void Drawn as 20 to 30 mm. The 570 mm total is taken at 20 mm. |
| 13 Knauf ceiling channel | Steel ceiling suspension channel | 15 mm | — | Carries the ceiling |
| 14 Pladur plasterboard ceiling | Gypsum board | 13 mm | — | Ceiling finish |
| Total | 570 mm |
An em dash means the source document does not state that value; it is not a zero. Layers within the joist depth are indented — they sit inside the joist, so the column does not sum to the total.
Calculated performance
| Property | Value | Basis |
|---|---|---|
| U-value, bridging corrected | 0.21 W/m²K | EN ISO 6946, one-dimensional steady state, with a +15% bridging correction for horizontal elements, applied as an engineering estimate. |
| Self-weight | 130 kg/m² | Mass estimate from the layers and dimensions in the source document. |
| Traditional equivalent | 481 kg/m² | Derived from the published self-weight and reduction percentage. |
| Weight reduction | −73% | Self-weight against the traditional equivalent build-up. |
| Fire resistance (EI) | Test programme in progress — contact technical department | Awaiting laboratory test report |
| Airborne sound reduction (R_A) | Test programme in progress — contact technical department | Awaiting laboratory test report |
| Structural span | Test programme in progress — contact technical departmentSpan selection tables in preparation | Awaiting laboratory test report |
| Watertightness | Test programme in progress — contact technical department | Awaiting laboratory test report |
U-values are one-dimensional steady-state calculations to EN ISO 6946. Bridging correction is applied as an engineering estimate: +20% for walls, +15% for horizontal elements. 2D numerical analysis to EN ISO 10211 is in progress; values will be updated on completion.
Not yet stated
- EIFire resistance · in test
- R_AAirborne sound reduction · in test
- spanStructural span · in test
- watertightnessWatertightness · in test
Test programme in progress — contact technical department
Weight against traditional
| Element | Solid System | Traditional | Reduction |
|---|---|---|---|
| D.09 Trafficable roof / terrace | 130 kg/m² | 481 kg/m² | −73% |
Where to use it
- Accessible roof terraces
- Communal amenity decks over occupied space
Design notes
- For terraces above approximately 25 m², convert to pedestal-supported paving.
- The external INSULTERM 600 of the façade must be continuous across the roof junction.
- Span selection tables are in preparation.