Shuttering Plywood 12 mm

What it is

Kitovu sells 12 mm shuttering plywood from its stock in Zanzibar at TZS 45,000 a sheet. It is the thinner of the two formwork sheets Kitovu keeps, made for the faces of forms where the panel is backed closely by timber: the sides of beams and walls, column boxes, footing edges, stair risers.

Kitovu has not yet confirmed the sheet size, whether the faces carry a film, or what wood the core is made of. The plywood sold on the island is mostly cut to 1220 × 2440 mm, as the price list of Zanzibaba Timber shows; ask on WhatsApp whether the sheets in stock are the same.

Lighter to handle

A thinner sheet is lighter to lift and carry around the site. Metsä Wood’s FormPLUS data sheet gives 8.2 kg/m² for its 12 mm birch panel, built from 9 veneers, against 12.2 kg/m² and 13 veneers at 18 mm. For a 1220 × 2440 mm sheet that is about 24 kg against 36 kg (our calculation). The sheets in Kitovu’s stock may be of another wood and weigh less or more; the figures show the gap between the two thicknesses, not the weight of this item.

How it is used

The trade-off for the lower weight is stiffness. A 12 mm panel bends more than an 18 mm one under the same wet concrete, so the timbers behind it have to sit closer together. That makes it a sheet for vertical faces and small forms, backed by studs at short centres, while slab decks with wider joist spacing are usually built with the 18 mm sheet. The spacing for a given pour comes from the formwork design, which works from the concrete pressure and the stiffness of the panel.

Behind the panels, Sawn Timber 50 × 50 mm (2 × 2) serves as light battens and edge strips, and 50 × 100 mm timber as studs and walings; both are in stock in Zanzibar.

Sheets for a wall or a column

A column 300 × 300 mm and 3 m high has four faces of 0.9 m² each, 3.6 m² in all, so two 1220 × 2440 mm sheets cover the faces of one column with offcuts to spare (our calculation). A wall form needs both faces: a wall 6 m long and 1.2 m high takes 14.4 m² of panel, about five sheets before cutting waste (our calculation).

Care between pours

Clean each sheet as soon as it is stripped and coat it with release agent before the next use. Keep sheets stacked flat, off the ground and covered, so they do not warp in the sun or soak up rain at the edges.

More on formwork materials and the order of stripping is on the formwork and shuttering page.