Osmaniye Düziçi Hacılar Central Mosque — Dome, Minaret and Formwork

This mosque in Düziçi shows well what it buys you to have the formwork shop and the site in the same hands. The main dome is cast on a timber centring, the half domes and squinches come off the same system, and the minaret rises stage by stage as in-situ concrete.

The clearest gain is at the şerefe. The muqarnas ring was not added in plaster on site; it came out of the concrete itself, from a mould whose negative was worked into a fibreglass shell. When the formwork was struck, the surface that appeared was finished as it stood.

Casting a dome on timber formwork

Dome formwork is a temporary structure carrying the weight of the fresh concrete and the operatives on top of it. Radial beams tie into a central tower, a curved decking is laid over them, and the scaffold is braced tier by tier. The critical point is that striking must not begin before the concrete has reached adequate strength — a dome struck early makes its crack pattern permanent.

The şerefe: a problem solved in the mould

The muqarnas ring, the balustrade openings and the upper chamfer were gathered into a single set of formwork. Solving those three separately produces joints and dimensional drift at the interfaces. Cast as one piece, the surface stayed continuous and the same geometry could be repeated on both minarets.

• The muqarnas negatives were worked into a fibreglass shell; the gel-coated face gave a smooth concrete finish.
• The balustrade openings were left as negatives in the mould — nothing was drilled or cut afterwards.
• A steel frame held the mould to shape against the pressure of the fresh concrete.

Formwork made in the same hands as the site

The formwork for this project was produced in our own workshop: shaft modules, the transition block and the muqarnas negatives. Buying formwork in turns every dimensional problem on site into a negotiation between two parties. In the same hands, a revision is one phone call away.