A wall panel made in the factory: two reinforced-concrete wythes enclosing an insulating core, tied by connectors, lifted and erected on site in a few hours. It is the wall of prefabricated construction — sheds, schools, commercial buildings — fast, precise and with the insulation already built in; the delicate points are the connectors (thermal bridges) and the sealing of the joints between panels.
Technical section of the system, from inside (left) to outside (right).
A wall panel made in the factory: two reinforced-concrete wythes enclosing an insulating core, tied by connectors, lifted and erected on site in a few hours. It is the wall of prefabricated construction — sheds, schools, commercial buildings — fast, precise and with the insulation already built in; the delicate points are the connectors (thermal bridges) and the sealing of the joints between panels.
A precast reinforced-concrete wall is a sandwich panel made on site or in the factory: an outer and an inner R.C. wythe with the insulation between them, cast together and tied by connectors. It arrives finished and is erected dry, by crane, very quickly.
The panel does everything at once: the inner wythe carries the loads (or transfers them to the frame), the core insulates, the outer wythe protects and gives the finish — smooth, exposed-aggregate, patterned. The insulation is built in and continuous, and the faces come ready: less site work, more factory-controlled quality.
The two wythes are tied by connectors crossing the insulation: if they are steel, they conduct heat and make point thermal bridges (and condensation risks); so today low-conductivity connectors are used (thin stainless steel, glass fibre). The connector must also carry the weight of the outer wythe and the thermal movements without cracking the face.
All the tightness is in the joints between the panels: they must be sealed with care — gaskets, sealants, decompression chambers — so water does not get in. Lifting and fixing to the structure need cast-in inserts and precise tolerances. Done well, it is a fast, durable system with good fire behaviour.
A precast sandwich panel does in one piece what a wall normally needs many trades for: an inner concrete wythe that bears (or braces), a continuous insulating core, and an outer wythe that protects and gives the finish — all cast in the factory and lifted into place in hours. Thermally it is excellent, because the insulation is continuous and uninterrupted across the whole panel. The one weak point is mechanical and thermal at once: the two wythes have to be tied together across the insulation by connectors, and if those are steel they conduct heat and create point thermal bridges (and condensation risks) right where they cross. The answer is low-conductivity connectors — thin stainless steel or glass-fibre — that carry the weight of the outer leaf and its thermal movements while letting through as little heat as possible. The rest of the performance is decided on site, in the careful sealing of the joints between panels.
All the watertightness of a prefab façade lives in the joints. The line works in two stages: an outer sealant takes the brunt of the rain, but the real seal is the inner gasket, kept dry; between them an open decompression chamber equalises the wind pressure so water is not driven through, and a small drain weeps out what little gets in.
A truss connector ties the outer wythe to the inner one across the insulation, carrying its weight and thermal movement; made of low-conductivity steel or glass fibre, it limits the thermal bridge. Cast-in inserts in the inner wythe take the lifting hooks and the fixings to the structure.
Informational links to the regulatory framework. Always verify the current text on the official source.
A ready-to-edit DOCX from this system’s data — build-up, performance, and cited regulations with their current in-force status. Courtesy draft, free.