The Secret Behind Tobikan’s Tiles
Tobikan has a distinctive appearance, a brick-red building set amid the greenery of Ueno Park.
Its exterior might look like brickwork, but it’s actually made of tiles.
These are thick, unglazed stoneware tiles with an elaborate shape that incorporates the brick joint into its design (fig. 1)– a little different from normal tiles, which tend to be flat and thin.
Generally, walls are tiled by spreading mortar onto the finished concrete wall as an adhesive, then laying thin tiles onto the mortar. But Mayekawa Kunio came up with the idea to let the tiles set at the same time as the concrete, in order to attach the thick stoneware tiles securely onto the walls.
The result was his unique cast-in tiling method (fig. 2).
① Wooden “laths” are fixed inside the wooden formwork into which the concrete will be poured in. Tiles are then arranged along the laths.
② Nails are hammered into the small holes in the tiles (found along the “groove” part), securing the tiles onto the laths and the formwork.This is why the tiles come with these smaller holes.
③ Separators are stuck into the larger holes (found at the center of the smaller tiles) and all the way through to the other side of the structure, so that the formwork won’t stretch out from the weight of the poured concrete.This is why the tiles come with these larger holes.
④ Wet concrete is poured into the wooden formwork, just like how concrete is usually cast.
⑤ After the concrete has solidified, the wooden formwork and the nails from ② are removed, revealing the finished wall with cast-in tiles.
These holed tiles are a distinctive feature of Mayekawa’s cast-in tiling method. Did you spot the little holes for the nails?
This tiling method is considered safe, as the tiles end up integrated with the concrete wall, and so are unlikely to fall off and cause injuries. Mayekawa always sought permanence in his architecture, and these cast-in tiles – a perfect match of material and method – can be said to be one of his great achievements. As part of Tobikan’s recent renovation (2010–11), the Special Exhibitions Wing and a section of the Central Wing were redone, using 85,000 new tiles.