Window — insPIRe® U sandwich panel (vertical layout, concealed fixing)

Junction function

Window in a wall made of insPIRe® U sandwich panels in vertical layout — an analogous detail to the S variant, but with a key difference resulting from the U joint geometry: the fastener is driven into the joint of the panel, invisible from outside. Therefore, the reveal flashings (OB-01, OB-02, OB-37) are fixed with external washer-head fasteners (item 13) at 250–300 mm spacing — these are the only visible fasteners around the opening.

Visual effect: clean, linear façade composition without the perforated line of screws characteristic of the S variant. A standard for premium buildings — office areas within industrial halls, car showrooms, representative facilities.

Critical installation aspects — differences vs S

• Window frame (item 03) — identical galvanised steel, fixed to the load-bearing structure behind the panel. The U panel does not change the geometry of the window frame.
• OB-01 and OB-02 — fixed with washer-head fasteners (item 13) VISIBLE from outside — these are the only visible perforations around the opening (in the S variant fasteners are also present in the panel joint = perforation in two places).
• PES sealing tape (item 08) between flashing and panel — more critical than in S, because the flat surface of the U panel has no protruding joint to create a “step” — the geometry requires good adhesion of the flashing.
• PU installation foam (item 09) — unchanged, low-expansion (expansion ≤ 30%).
• Neutral silicone (item 10) — unchanged.
• Sill OB-37 (item 07) — identical to S, but fixed to the flat surface of the U panel (easier installation, fewer gaps requiring sealing).
• Opening edge zone — fasteners within a 30 cm strip from the opening at double density, fixed to the structure through the U panel joint (invisible).

U vs S — window geometry

Aspect	U (concealed)	S (visible)
Visible fasteners around opening	only OB-01/OB-02 (3 sides)	additionally visible panel fasteners
Flashing installation time	longer (precision at PES sealing tape)	shorter
Façade aesthetics	smooth, premium	industrial
Cost per opening (panel + flashings)	+20–25% vs S	baseline
Typical use	offices, showrooms, representative	halls, warehouses

Used in the insPIRe® U concealed-fixing hall wall system.

Documentation

Gór-Stal Technical Catalogue 2025, p. 60 — window in vertical layout, Variant I, vertical section, U panel (concealed fixing).

Components in this junction