Systems featuring GUARDEX®: the glass-mat board that encloses the framework and supports the external wall insulation

Solutions & Applications · Facades & Dry Construction

The lightweight framework is completed in a few days; the external wall insulation requires good weather and a contractor crew. In the interim, the building envelope remains exposed. GUARDEX® is the glass-mat board that encloses the framework from the outside, protects the building until the external wall insulation is installed and acts as its substrate — non-combustible, moisture-resistant and free from paper that could go mouldy.

What is GUARDEX®?

Plasterboard with a core of special plaster and glass fibre mesh instead of paper on both sides. It contains no organic paper, so it does not harbour mould and does not delaminate when wet — the key difference from a moisture-resistant plasterboard for internal use.

Feature	GUARDEX® 12.5 mm
Type in accordance with EN 15283-1+A1	GM-FH1R
Reaction to fire (EN 13501-1)	A1 — non-combustible
Water absorption	H1 (≤ 2,5%)
Dimensions	1,200 × 2,400 mm and 1,200 × 2,000 mm
Surface mass	~12 kg/m² (34.5 kg per 2,400 mm slab)
End type	AK
A never-ending exhibition	Up to 12 months, with sealed joints

The code GM-FH1R is read letter by letter: GM glass fibre, F improved core cohesion at high temperature, H1 reduced water absorption, R increased strength. This is the identification required by an external cladding specification — not the colour of the panel.

Three applications to the building envelope

Application	The structure	What are the benefits?
External walls of lightweight construction buildings	Steel or timber frame · GUARDEX® on the exterior · external wall insulation	A multi-storey building envelope that can be completed quickly and is suitable for ETICS without an intermediate layer
Filling walls between concrete slabs	Framework between slabs; mineral wool in the framework; GUARDEX®; ETICS applied in front of the slabs	Lighter and quicker to install than masonry, continuous thermal insulation in front of the facades
Ventilated façade substrate	Framework · GUARDEX® as a wind barrier · sub-frame · panels, stone or timber	Non-combustible, moisture-resistant sheet behind the ventilated cavity

The greatest benefit lies in load-bearing walls. The external wall insulation runs continuously in front of the slab faces, where a thermal bridge would normally occur in conventional masonry. The mineral wool within the frame enhances thermal and acoustic performance without increasing the external thickness of the wall.

Glass-mat board or cement board?

Three types of external-use slabs perform similar functions but are based on different principles:

Slab	Nature	Massa	When is it preferable?
GUARDEX®	GM-FH1R glass-mat board · A1	~12 kg/m²	ETICS and ventilated façade substrates, lightweight cladding, extensive on-site display
GLASROC-X	Cellulose-free glass-mat board	~11.2 kg/m²	External cladding and temporary protection of the structural frame
AQUAPANEL® Outdoor	Cement board · A1 · 100% water-resistant	16 kg/m²	Render applied directly onto the slab, areas subject to continuous wetting, curved facades (radius up to 1 m)

GUARDEX® is a substrate — its performance is judged by the insulation

The slab encloses and protects the framework; the thermal and fire performance of the façade is determined by the system installed on top of it. The choice of insulation is made on a zone-by-zone basis for the façade:

Insulation	λD	Reaction to fire	Where it fits
FIBRANgeo BP-ETICS	0.035 W/(m·K)	A1	Multi-storey buildings where a non-combustible system and sound insulation are required; CS(10) ≥ 30 kPa
GRAFIT EPS-80	0.030 W/(m·K)	E	Maximum thermal performance with the thinnest possible thickness
FIBRANxps ETICS GF	0.033–0.036 W/(m·K)	E	Base course and plinth, where the façade is exposed to water from the ground; WL(T) 0.7–1.5 per cent

A common configuration: XPS in the base zone, stone wool or graphite-coated EPS on the rest of the façade, over the same GUARDEX®. For an exposed concrete finish, the Ceretherm Visage Concrete system provides the texture without the weight of concrete.

Three points that are often overlooked

1. Screws for external use: with enhanced corrosion protection, suitable for concrete slabs — not standard internal plasterboard screws. A rusty screw behind the external wall insulation will show up as a blemish on the finished surface.
2. The 12-month exposure period requires sealed joints: using the jointing materials specified by the manufacturer. Open joints mean water ingress into the structure, however good the slab may be.
3. The cladding system comprises the following: GUARDEX® is the substrate. The thermal insulation, reinforcement and render — or the framework of the ventilated façade — form a certified assembly and are specified together.

Design series

1. Shell type: lightweight load-bearing frame, infill wall between slabs or ventilated façade substrate.
2. Framework: CW/UW metal or timber, with stud spacing as per the system sheet.
3. Frame filling: mineral wool for the thermal and acoustic performance of the wall.
4. Outer sheet: GUARDEX®, or AQUAPANEL® Outdoor, where the render is applied directly to the board.
5. Exposure time: the number of months the building envelope will remain unfinished — this determines the sealing of the joints.
6. Insulation by zone: non-combustible requirement, base zone, U-value target.
7. Finish: thin-coat ETICS render, exposed concrete finish or ventilated cladding.

Exterior Cladding Panels

Framework & Infill

Thermal insulation on GUARDEX®

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