How Is GRC Board Installed?

Installing GRC Board involves far more than screwing the board to a metal profile. A successful mechanical clinker façade requires the existing substrate, anchor design, insulation and moisture layers, profile grid, board joints, clinker bonding and grouting to be treated as one system.

The sequence below describes a general installation approach. Bracket section, anchor type, profile spacing, screw layout and movement-joint locations must be determined by specialists according to the project’s structural and architectural conditions.

1. Survey and collection of project data

The first step is to measure the façade and identify the load-bearing substrate. Reinforced concrete, brick, pumice block and aerated concrete do not use the same anchoring solution. Façade height, building location, openings, corners and existing wall deviations are recorded.

• The net façade area and door/window openings are measured.
• The wall’s plumb and plane are checked.
• Wind load and anchoring capacity are assessed.
• Sill, parapet, drip and drainage details are drawn.

2. Brackets and subframe

Project-suitable L-brackets are fixed to the primary structure, and vertical support profiles are connected to them. Bracket length is selected by considering insulation thickness, the required air cavity and façade adjustment allowance together.

Correct use of fixed and sliding connections reduces stresses caused by thermal movement. Because a small deviation in the profile grid becomes amplified and visible across the clinker courses, plane checks are repeated throughout installation.

3. Insulation and moisture management

Where thermal insulation is specified, mineral-wool boards are fixed to the substrate with an appropriate anchor pattern. Moisture membrane joints are lapped and continuity is secured with tapes. Bracket penetrations, window surrounds and horizontal terminations are detailed to prevent uncontrolled water entry behind the system.

4. Fixing the GRC Board sheets

The 605 × 1250 mm brick-grooved GRC Board sheets are positioned so that joints remain over supporting profiles. Gaps between boards follow the manufacturer’s requirements, and screw heads are tightened without crushing the board. Edge distances and screw spacing are maintained.

1. The bottom starting line is levelled.
2. The first board is positioned to suit the profile grid.
3. Joint gaps and vertical alignment are checked.
4. Cut edges are cleaned, and no unsupported joint is left.
5. Movement joints are continued in accordance with the architectural details.

5. Clinker brick installation

Dust and loose material are removed from the board surface. A system-compatible C2TE-class flexible adhesive is prepared and used within its working time; where required, it is combed onto both the substrate and the back of the brick. Bricks are positioned using the board grooves as a guide.

For products with natural colour variation, blending bricks from different boxes reduces unwanted colour blocks on the façade. Horizontal and vertical joints are checked at regular intervals.

6. Grouting, cleaning and final inspection

Once the adhesive has set sufficiently, joints are filled continuously. Grout consistency, depth and finish affect water management as well as the façade’s appearance. Material on the brick face is cleaned by an appropriate method before it sets.

The final inspection covers loose elements, unfilled joints, cracks, staining, drainage details, corners and returns at openings. Horizontal and vertical lines across the façade are reviewed again before project handover.

The most common on-site mistakes

• Starting installation without checking the load-bearing substrate and anchoring capacity.
• Failing to plan the profile grid around the board dimensions.
• Leaving a board joint unsupported or overtightening screw heads.
• Using an unsuitable adhesive or exceeding its open time.
• Neglecting movement joints, sills and drainage details.
• Proceeding with the whole façade without a mock-up area.