Fibre Reinforced Facade Encyclopedia: Finishes
Texture and relief are three-dimensional patterns formed in the face of a panel by the mould, from a shallow grain a fraction of a millimetre deep to a modelled relief of 50 mm or more. The distinction from the other surface finishes is the mechanism. Polished, acid etched, sandblasted and exposed aggregate finishes are made by removing material after casting; texture is made by the mould face during casting, so it costs mould money rather than labour money.
A CNC-milled mould for a modelled relief may cost several times a flat mould, but that cost is divided by the number of panels cast from it. Across 40 panels it is a minor line item. Across 2 panels it dominates the price.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Mechanism | Formed by the mould face | Cast in, not applied or removed afterwards |
| Shallow texture | 0.5 to 3 mm relief | Timber grain, linen, fine ribbing, formliners |
| Medium relief | 3 to 20 mm | Flutes, reveals, board-marked and profiled patterns |
| Deep relief | 20 to 60 mm or more | Modelled and sculptural forms |
| Draft angle | Typically 3 to 7 degrees on vertical faces | Zero draft needs a split or flexible mould |
| GRC skin thickness | 10 to 20 mm over the relief | Relief adds section depth, not skin thickness |
| Mould material | CNC-milled MDF, tooling board, timber, GRP, rubber | Reuse count drives the selection |
| Typical mould reuse | 5 to 20 casts for MDF, 50 or more for GRP | Rubber formliners typically 20 to 100 casts |
| Weight effect on GRC | Typically adds 0 to 10 kg/m2 | Depends on the extra material the relief holds |
How texture is produced
Everything visible on a cast panel face is a negative of the mould face, so texture is a mould-making problem. On current work the relief is modelled in the facade geometry, toolpaths are generated from that model, and a CNC machine mills the mould directly, which is the process described on the CNC formwork page.
Three mould routes are common. A milled mould, cut in high density MDF, polyurethane tooling board or timber, gives sharp control of a bespoke pattern and suits sculptural relief. A cast mould, where a master is milled once and rubber or glass reinforced polyester working moulds are taken off it, suits a pattern repeated many times because only the working moulds wear. A proprietary formliner, an off-the-shelf elastomeric sheet in a catalogue pattern, is cheapest where a standard board-marked, ribbed or stone pattern is acceptable. A fourth route, a sacrificial mould destroyed to release a panel with undercuts, removes the draft constraint and costs a mould per panel, so it is reserved for one-off sculptural pieces.
Draft, undercut and demoulding
The constraint that governs texture design is draft: the taper on every face that runs in the demoulding direction. Without it the panel and mould lock together and releasing them either cracks the panel or destroys the mould. As a rule of thumb, vertical faces want 3 to 7 degrees, more on a deep relief, more again on a rough mould face where friction is higher, and less is possible on a smooth polished mould with a good release agent.
Undercuts, where the relief is wider at the face than at its root, change the tooling: a split mould that opens in pieces, a flexible rubber insert that stretches over the undercut, or a sacrificial insert. All three add cost, and split moulds add a witness line on the panel face that has to be located deliberately, in a shadow or at a pattern boundary.
What the materials will and will not do
Sprayed glass fibre reinforced concrete is the most capable of the facade materials for relief, because the material is placed by gun against the mould face rather than poured, so it follows deep and complex geometry without needing to flow. The limits are that the spray head needs access into the relief, setting a minimum width to depth ratio, and that skin thickness has to be maintained around the relief rather than thinning over an edge. Fibre reinforced polymer goes further: a laminate is thinner and picks up a mould face with almost no loss of definition, so very fine texture reproduces better in FRP than in a cementitious panel. Glass fibre reinforced gypsum reproduces fine detail extremely well and is the interior material of choice for modelled relief.
Cost, repetition and programme
The economics of texture are mould economics. Almost all the cost sits in tooling, and tooling is a fixed cost divided by the number of panels taken off it. A facade that repeats one modelled relief across forty panels often carries a lower mould cost per square metre than a facade of forty individually shaped flat panels. The decision that saves money is not making the relief shallower; it is reducing the number of distinct moulds by rationalising the pattern into a smaller family of tiles that can be rotated, mirrored or offset to read as variety.
How it is specified and sampled
- Provide the relief as three-dimensional geometry, not as an elevation with hatching; the mould is cut from a model
- State the nominal relief depth and the tolerance on it
- State the minimum draft angle accepted, or require draft to be shown on shop drawings
- Nominate where split lines or mould witness marks may fall
- Nominate the surface finish applied over the relief, and require the sample to show it in the relief rather than on a flat coupon
- Require a full-size or full-repeat first-off panel viewed vertically outdoors in raking light
Raking light is the point most often missed. Relief is read by shadow, so a textured panel that looks correct under flat factory lighting can look flat or noisy on the building. View the first-off panel outdoors, vertically, at the orientation it will occupy, at more than one time of day.
Standards and references
- GRCA Specification for the Manufacture, Curing and Testing of GRC Products (moulds, finishes and tolerances)
- AS 3610.1 Formwork for concrete, surface finish classes and formed surface tolerances
- PCI MNL-117 Manual for Quality Control for Plant Produced Architectural Precast Concrete (form liners and textures)
- PCI Architectural Precast Concrete, texture and form liner selection guide
- AS 3600 Concrete structures, for the supporting structure and fixings behind a moulded panel
- AS/NZS 1170.2 Wind actions, which governs the panel behind the texture (check the edition of the NCC adopted in your jurisdiction)
Where this matters on a ShapeShift project
Spanda: A large sculptural form where the geometry is the product, made from digitally cut moulds. The same tooling logic applies to a repeating facade relief.
Related terms
Questions specifiers ask
How deep can a textured panel relief be?
Shallow texture is 0.5 to 3 mm, medium relief 3 to 20 mm, and deep modelled relief 20 to 60 mm or more. The limits are not really depth but draft, demoulding and the access the spray head or laminator needs into the relief.
Why does draft angle matter?
Without taper on the faces running in the demoulding direction, the panel and mould lock together and one of them is damaged on release. Typical vertical faces want 3 to 7 degrees, more for deep or rough-faced relief. Zero draft or an undercut needs a split, flexible or sacrificial mould.
Is texture applied after casting?
No. Texture and relief are formed by the mould face during casting. The finishes worked after casting, such as acid etching, sandblasting, exposed aggregate and polishing, are applied over the cast texture and are a separate decision.
Does a deep relief cost more per square metre?
Almost all the cost is tooling, and tooling is divided by the number of panels cast from the mould. A modelled relief repeated across forty panels can cost less per square metre than forty individually shaped flat panels.
How should a textured panel be sampled?
With a full-size or full-repeat first-off panel carrying the specified finish over the relief, viewed vertically outdoors in raking light at the orientation it will occupy. Relief is read by shadow, so a flat-lit factory sample tells you very little.
Have a relief modelled but not resolved for manufacture? We take facade geometry through mould design, draft and tooling as one step. Send us the geometry
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.