HDIII Wall System · Formwork Block · Infill
Isotex HDIII 38/17 Graphite Wood-Cement Formwork Block
Code: HDIII-38/170.15U-value W/m²K (2D)
12h 36'Phase shift
REI 120Fire rating
38 cmWall depth
CE · ETA 08/0023 REI 120 EPD S-P-01472 EC8 seismic Bureau Veritas
Thermal performance
0.15 W/m²K (2D)
UNI EN ISO 6946 + UNI EN 10355. Independently tested by ITC-CNR. 3D value not published for this product.
Thermal inertia
12h 36' phase shift
Wood-cement and concrete mass absorbs heat by day and releases it at night.
Acoustic performance
Rw 53 dB
Wood-cement absorbs noise at low and high frequencies simultaneously.
Fire resistance
REI 120
Load-bearing capacity, integrity and insulation maintained. Reaction to fire B-s1,d0. LEPIR II façade test passed.
01Overview
Compliance summary
✓ CE marked ETA 08/0023
✓ REI 120
✓ EPD S-P-01472
✓ EC8 seismic Zone 4
Primary use
Infill
Suited for the wall type stated. Concrete core thickness determines structural capacity — see Technical Specs for exact figures.
Also suitable
Party walls · stair cores · basements
Higher REI, acoustic separation and structural continuity all met without changing specification.
02Technical specifications
Thermal
| U-value (display · 2D) | 0.15 W/m²K |
|---|---|
| U-value 2D | 0.15 W/m²K |
| Calculation standard | UNI EN ISO 6946 · UNI EN 10355 |
| Phase shift | 12h 36' |
| Periodic transmittance Yie | 0.010 W/m²K |
| λ EPS (Neopor® BMBcert) | 0.031–0.034 W/mK |
| λ wood-cement shell | 0.10 W/mK |
| Block density | 534 ±10% kg/m³ |
Physical dimensions
| Overall wall depth | 38 cm |
|---|---|
| EPS insulation | 17 cm |
| Concrete cast core | 12 cm |
| Shell thickness | 4.5 cm |
| Block length | 500 mm |
| Block height | 250 mm |
| Coverage | 8 blocks/m² |
Acoustic & structural
| Acoustic | Rw 53 dB |
|---|---|
| Test standard | UNI EN ISO 10140 · UNI EN ISO 717 |
| Fire resistance | REI 120 |
| Reaction to fire | B-s1,d0 |
| Max indicative load | 28 t/m * |
| Concrete fill | 104 L/m² |
| Block weight | 88 kg/m² |
| Seismic | EC8 · NTC 2018 |
* Indicative at RcK ≥ 30 N/mm², inter-floor h 3.00 m. A qualified structural engineer must verify capacity for your project and national code.
03Wall construction
External render
Silicone or mineral render direct to wood-cement face. No mesh or primer required.
15–25 mm
Wood-cement outer shell
Factory-cast. Vapour-permeable. Density 534 kg/m³. 4.5 cm thick.
Integrated EPS — Neopor® BMBcert
Factory-integrated. No site cutting, no thermal bridges.
17 cm
Reinforced concrete core
Poured in situ, S4 consistency. Cast every 5–6 courses.
12 cm
Wood-cement inner shell
Direct plaster or plasterboard without battening. Vapour-open.
Internal plaster / finish
Lime or gypsum plaster applied directly. No stud frame required.
12–15 mm
Isotex system advantage
Factory-integrated layers. No separate insulation trade, no wall ties, no thermal bridging through fixings. Block length 500 mm × height 250 mm = 8 blocks per m². Render externally, plaster internally direct to wood-cement face.
04Installation
- 01Foundation & DPCPrepare foundation to tolerance. Install DPC. Place vertical rebar at 25 cm pitch protruding ~50 cm before first course.
- 02Dry-stack block layingLay dry — no mortar. Stagger each course by half a block (250 mm). 500 mm block length, 250 mm height, 8 blocks/m².
- 03Reinforcement placementVertical rebar at 25 cm pitch through cavities. Horizontal rebar in rebate grooves every course.
- 04Concrete pour — every 5–6 coursesFilling volume 104 L/m². Keep concrete mid-way through final course. Vibrate with small needle vibrator.
- 05Curing & finishingBlocks remain permanently in place. Render externally and plaster internally after standard curing.
No mortar joints
Dry-stack — no mixing, no waiting. 3–4× faster than traditional masonry.
8 blocks per m²
500 mm length × 250 mm height. Factory-integrated insulation — weathertight as soon as blocks are placed.
Direct finish surfaces
Render externally and plaster internally direct onto wood-cement. No substrate or battening required.
05Certifications
CE · ETA 08/0023
European Technical Assessment
ITC-CNR factory production control. CE marking per EN 15498. EU Construction Products Regulation (CPR). Isotex: European leader with 82% market share in wood-cement sector.
REI 120
Fire resistance
Load-bearing capacity, integrity and insulation maintained 120 minutes. Reaction to fire B-s1,d0. LEPIR II façade test passed.
EPD S-P-01472
Environmental Product Declaration
Bureau Veritas · Accredia. ISO 14025:2006 and EN 15804:2012+A2:2019/AC:2021. Valid until 2029-03-20. Cradle to grave + Module D. 100-year reference service life. 48% recycled/re-used content per m².
EC8 · NTC 2018
Seismic compliance
Eurocode 8 and Italian NTC 2018. Zone 4 verified. 400,000+ eco-sustainable buildings since 1985.
ReMade in Italy
Recycled content
Bureau Veritas certified. 48% per m² recycled/re-used/by-product content. 100% recycled wood from end-of-life pallets. Neopor® BMBcert EPS — Isotex Green (15% recycled) or Isotex Total Green (100% recycled, Class A+).
VOC — Indoor Air Comfort Gold
Indoor air quality
Per UNI EN 16516 · UNI EN ISO 16000-9. Indoor Air Comfort Gold certification. No VOCs released during normal use.
06Isotex HDIII 38/17 Graphite Wood-Cement Formwork Block vs traditional cavity wall
| Specification | Isotex system | Traditional cavity wall |
|---|---|---|
| Thermal bridges | ✓ None — integrated EPS | Wall ties, lintels, reveals |
| Trades on site | ✓ 1 (block layer) | 3–4 minimum |
| Internal finish | ✓ Direct plaster | Batten + board |
| Fire rating | ✓ REI 120 (intrinsic) | Separate fire spec |
| Site waste | ✓ Minimal — dry-stack | Mortar, packaging, off-cuts |
| Seismic | ✓ EC8 Zone 4 verified | Additional engineering req. |
07Downloads
Specify Isotex HDIII 38/17 Graphite Wood-Cement Formwork Block
Request your technical pack, CAD drawings or BIM objects. Our technical team responds within 72 hours and supports specification, structural queries and PassivHaus sign-off.
CE ETA 08/0023 REI 120 EPD S-P-01472
0.15U-value W/m²K (2D)
REI 120Fire rating