LIFE IN AN OLD JAPANESE HOUSE VOL.3: Old Japanese Homes and their Roofs

Whenever I look at the condition of an old home, the first thing I check is the roof’s condition. The roof is of key importance when examining the degree of upkeep done on a house. The shape of the roof and selection of roof tiles further tells me the history of the home as well as revealing the area’s climate and culture. A good demonstration of this is the contrast of roofs one can see when traveling from the warm temperate climate of the Setouchi inland sea, and traveling north through the Chugoku mountains up to the cold Japan sea. On one hand, the materials and tiles used in the Setouchi area vary greatly with unglazed roof tiles being a common sight. Once you cross over to homes located in the snowy mountains, you’ll soon see waterproofed tiles and roofs built to prevent snow from falling. Finally upon reaching the Japan Sea, you’ll see the locally produced reddish-brown ‘Sekishu’ tiles which are coated to be resistant to salt-air damage and snow. It’s fascinating to discern the place where snowfall increases or where the trade routes change. If you venture to some small farming villages, you’ll find that thatched roofs still remain. Unfortunately, the skill of repairing and maintaining these roofs is dying out so most thatched roofs end up being covered with galvanized metal.

A view of the diverse roofs by the Setouchi seaside

A common sight by the Japan sea, here are the red ‘Sekishu’ tiles which are fully glazed to resist salt air and water damage.

An example of a thatched roof now covered with galvanized metal.

Thatched roof of the Kawahara-tei that located in Okayama ; here is a structure with its thatched roof intact. Upkeep on a thatched roof proves to be a great challenge in modern times.

If you are considering moving into an old home somewhere in Japan, checking the roof condition is of key importance. Minor roof leaks in small places aside, tackling roof repair with your own two hands is a tall order for most home repair enthusiasts. By and large roof repair is left up to a professional which ends up being an exorbitant cost.

If the roof of the home you are considering residing in does need repair, it’s best to act as soon as possible. For Japanese homes constructed from wood in places with high humidity, poor air circulation, and heavy degrees of rainfall, they will quickly deteriorate resulting in holes opening in the roof or the house starting to crumble. In the period of a few years such a home will be irreparable.

A house left with roof leaks with lead to holes opening up and eventually the roof falling in.

It’s important to weigh several key factors when determining the amount of repair necessary for a roof. One must think of the materials and method of construction, as well as the weight of the roof against the durability of the building.

If the structure has few structural pillars and bearing walls, or limited bracing, as well as poor earthquake resistance then homes with heavy roofs such as thatching or ceramic tiles are at risk of collapse in the event of an earthquake. Further, roofs and homes made with light materials are at risk of blowing off in the event of typhoons or heavy gusting winds. Ideally, a house would have study construction with firm pillars, bearing walls and bracing plus a good foundation and walls with heavy ceiling tiles laid on the roof to ensure safety during a typhoon. That said, if you don’t wish to add on more walls and pillars to the structure to support a heavy roof, then a method of securing the house and roof built with lighter materials is needed.

Also, roofs built in the past with ceiling tiles used roofing boards made from cedar and then attached cedar bark on the boards then further laid clay on top of the bark and finally affixed the tiles to the clay. During an earthquake this traditional construction method can result in tiles sliding off the roof which means that even if there is no roof leak, it may be a good idea to redo the roof with modern construction materials. In place of bark, waterproof sheets should be laid and then in place of clay, adhesive urethane foam used, and finally the ceiling tiles could be screwed in place which would reduce the risk of them failing as well as decreasing the risk of roof leaks.

Repairing a roof cheaply to stop roof leaks usually means corrugated metal is installed over roofing tiles. The lifespan of corrugated metal is anywhere from 10 to 20 years, when rust forms on the metal, it can be removed and repainted if the rust isn’t too severe. Once holes are forming in the metal then it must be replaced. Galvalume steel sheets are more durable as they typically last from 20 to 30 years. In recent years some Japanese homes will use galvalume steel shaped like traditional ceiling tiles to retain the traditional look.

One other ceiling tile is the type made from cement which was popular because of their affordability during and after WWII. Although it is said that these tiles can last 30 to 40 years, if they are not repainted every 10 years they lose their resistance to water and will begin to crumble. It is sadly common for cement tiles to not be properly maintained.

The most durable tiles are ceramic tiles made from clay which can last anywhere from 50 to 100 years. 

Here we see paint peeling off cement tiles.