Polyurethane Facade Installation Guide
The correct installation sequence on a facade, critical points and common mistakes — in eight steps.
With polyurethane facade elements the sequence is mandatory: if chemical (adhesive) and mechanical (screw) fixing are not used together, joints open over time with thermal movement. This guide gives the eight steps from surface preparation to the topcoat, each with its critical point. Silicone-based adhesive is never used.
Required Materials and Tools
• Fine-tooth hand saw or mitre saw
• PU-based mounting adhesive (NOT silicone)
• Screws of suitable length and a cordless driver
• Acrylic / exterior filler
• 180-220 grit abrasive
• System primer of the topcoat brand
• Elastic, UV-resistant facade paint
• Damp cloth (for squeeze-out)
• Scaffolding / safe working platform
Step-by-Step Application
- Surface preparation — The substrate is cleaned of dust, grease, dirt and moisture; loose plaster and paint are scraped off before installation. The surface must be dry and sound.
- Measuring and cutting plan — Measurements are taken from the wall surface where the element will sit, not from the window frame. The material is too dense for a utility knife: use a fine-tooth hand saw or a mitre saw, with 45° mitres at corners. Filling a bad cut with filler leads to cracking and paint loss.
- Dry fit — Parts are held in place before screwing; axis alignment, mitre angles and how the joints meet are checked.
- Bonding (chemical) — Silicone-based adhesive is forbidden. A PU-based mounting adhesive is applied in an uninterrupted bead — not only on the face against the wall but on ALL joints between adjacent and stacked parts. Squeeze-out is wiped with a damp cloth before it cures. Curing takes about one hour in normal conditions and longer in cold weather.
- Screwing (mechanical) — Adhesive alone is never relied upon. Outdoors the parts are CROSS-screwed at the joints so that thermal movement and wind do not open them. Screw heads are sunk into the material. A 240 cm column shaft is screwed from both sides at top, middle and bottom; capital and base take two screws on each side.
- Filling and sanding — Screw heads, joints and level differences are filled flush with acrylic/exterior filler. Once dry, the marks are removed with 180-220 grit.
- Priming — Before painting, the WHOLE surface is lightly matted with 180-220 grit and cleaned (release-agent residue pushes paint off). Primer is applied homogeneously to the whole surface, not spot-applied, otherwise absorption differences over filled areas leave tonal marks. The primer must be the system primer of the topcoat brand.
- Topcoat — A highly elastic, UV-resistant facade paint is applied outdoors. The number of coats and waiting times follow the technical data sheet of the chosen paint system. An unpainted surface yellows under UV.
What to watch when working at height
Polyurethane elements are light enough to need no crane and can be handled on scaffolding by a single craftsman. Mechanical fixing is even more critical at height: because of wind load no screw may be skipped and joints must be cross-screwed. When long profiles are butted together, adhesive is always applied to the joint.
What changes with thermal movement and steel frames
In steel substructures, thermal expansion joints must be absorbed with elastic mastic, since metal flexes both vertically and horizontally. The mastic decouples the joint from the building so movement is not transferred to the polyurethane facade as hairline cracks. Concrete is never poured inside a column; where a load exists a steel frame carries it.
Common mistakes and their consequences
Skipping adhesive on the joint or omitting screws comes back as a crack at the joint. Using silicone-based adhesive leads to flexing and opening over time. Skipping or spot-applying primer causes peeling or tonal differences. An unpainted surface yellows. Water or moisture ingress from behind pushes the paint off; paint must not be renewed before the source is fixed.
Frequently Asked Questions
Can a polyurethane facade element be installed with adhesive only?
It should not. Outdoors, adhesive and screws are used together; cross-screwing at the joints prevents them opening with thermal movement and wind.
Which adhesive is used?
A PU-based mounting adhesive. Silicone-based adhesive is forbidden. Curing takes about one hour in normal conditions and longer in cold weather.
Which tool is needed for cutting?
The material is too dense for a utility knife. Use a fine-tooth hand saw or a mitre saw, with 45° mitres at corners.
How are screw heads covered?
Screw heads are sunk into the material, filled flush with acrylic/exterior filler and sanded with 180-220 grit once dry.
Is primer mandatory?
Yes. It secures adhesion against release-agent residue, and for warranty purposes it must be the system primer of the topcoat brand.
When is paint applied after installation?
After filling and sanding are complete and the surface is clean, a homogeneous primer is applied, then the topcoat following the waiting times in the paint system’s data sheet.
Do you send an installation team to the site?
Supply and installation are separate: the quoted figure covers the products only, and fitting is carried out by the contractor or applicator on site. Delivery is ex works, so transport is arranged by the buyer, and consignments should be inspected on the day of collection and picked up within ten days of the readiness notice. Site survey, measurement, analysis and 3D scanning can be arranged as chargeable services and are priced in the quotation.
Can you choose facade profiles from photos of my house?
Photographs help the sales team narrow down suitable models and proportions, but they are not a measurement basis. Elevation heights, window and door opening dimensions, corner returns and the substrate type are needed before profile sections are fixed, because a cornice that reads well in a photo can crowd a short pier once real dimensions are applied. Where the facade is irregular or already built, on-site measurement or 3D scanning is offered as a paid service.
Can facade profiles be fixed over exterior insulation?
Only if the mechanical fasteners reach a solid substrate behind the insulation board or an embedded batten anchored to it. Adhesive applied to an insulation face transfers the load to the weakest layer, so the fixing pattern has to be planned before the boards are closed and rendered. Mark anchor positions during the insulation stage, then combine PU-based mounting adhesive with those mechanical fixings; silicone is never used as the bonding material.