HB Formwork · Formwork Block · Load-bearing

REI 120 Load-bearing CE · ETA 08/0023

Isotex HB 25/16 Wood-Cement Formwork Block

Code: HB-30/19

0.68U-value W/m²K

REI 120Fire rating

300 mmWall depth

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CE · ETA 08/0023 REI 120 EPD S-P-01472 EC8 seismic Bureau Veritas

Thermal performance

0.68 W/m²K

UNI EN ISO 6946 + UNI EN 10355. Independently tested by ITC-CNR.

EN ISO 6946NZEB ✓

Thermal inertia

—

Wood-cement and concrete mass absorbs heat by day and releases it at night.

EN ISO 13786

Acoustic performance

55 dB Rw

Base tested wall. Enhanced assembly with IsolGypsum Fibra build-up can reach Rw 61 dB.

EN ISO 717-1

Fire resistance

REI 120

Load-bearing capacity, integrity and insulation maintained. Reaction to fire B-s1,d0. LEPIR II façade test passed.

NF EN 13501-2

U-value position in HDIII range — 3D method (lower = better performance)

↙ Better performance Higher U-value ↗

HB-30/19
0.68

44/20
0.15

38/14
0.21

30/7
0.34

01Overview

Compliance summary

✓ CE marked ETA 08/0023

✓ REI 120

✓ EPD S-P-01472

✓ EC8 seismic Zone 4

Primary use

Load-bearing

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.

02 Block anatomy

300 mm total

300 mm. 3 layers.

Four integrated layers. No assembly on site — the block arrives as a complete wall system ready to dry-lay.

Outer wood-cement face

Mineralised spruce + Portland cement. Protects EPS. Breathable — µ=5.9 vapour permeability. Fire Class B-s1,d0. Acts as permanent external formwork.

45mm

Reinforced concrete structural core

Poured in situ every 5–6 courses. Provides structural continuity, acoustic mass (55 dB Rw), thermal inertia and seismic resistance.

210 mm

Inner wood-cement face

Symmetrical inner shell. Fire protection from interior side. Accepts plaster and finishes direct. Vapour-open — no condensation risk.

45mm

Total block depth 300 mm

02Technical specifications

Thermal

U-value (display · 3D)	0.68 W/m²K
U-value 3D	0.68 W/m²K
Calculation standard	UNI EN ISO 6946 · UNI EN 10355
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	300 mm
Concrete cast core	210 mm
Block length	500 mm
Block height	250 mm
Coverage	8 blocks/m²

Acoustic & structural

Acoustic	55 dB Rw
Enhanced assembly	Rw 61 dB (with IsolGypsum Fibra)
Test standard	UNI EN ISO 10140 · UNI EN ISO 717
Fire resistance	REI 120
Reaction to fire	B-s1,d0
Max indicative load	26 t/m ^*
Concrete fill	160 L/m²
Block weight	95 kg/m²
Single block	11.9 kg
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.

Reinforced concrete core

Poured in situ, S4 consistency. Cast every 5–6 courses.

210 mm

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.

05Installation

We are sending you pictures of the residence built in Norcia in HDIII blocks with graphite and reinforced concrete. We are very pleased with the product, especially for its earthquake resistance. We can confirm that the house did not suffer any damage as a result of the magnitude 6.5 earthquake that occurred a few days ago.

Engineer Boccanera — Boccanera Ivo e Fratelli Snc Norcia (PG), August 2016 — Central Italy earthquake

01
Foundation & DPC
Prepare foundation to tolerance. Install DPC. Place vertical rebar at 250 mm pitch protruding ~500 mm before first course.
02
Dry-stack block laying
Lay dry — no mortar. Stagger each course by half a block (250 mm). 500 mm block length, 250 mm height, 8 blocks/m².
03
Reinforcement placement
Vertical rebar at 250 mm pitch through cavities. Horizontal rebar in rebate grooves every course.
04
Concrete pour — every 5–6 courses
Filling volume 160 L/m². Keep concrete mid-way through final course. Vibrate with small needle vibrator.
05
Curing & finishing
Blocks 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 HB 25/16 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

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Specify Isotex HB 25/16 Wood-Cement Formwork Block

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CE ETA 08/0023 REI 120 EPD S-P-01472

0.68U-value W/m²K

REI 120Fire rating