Ichinose Kawara Kogyo Ltd is a roofing professional. Contact us for inquiries regarding kawara and roofing works including renovation and repair.
瓦の豆知識 瓦屋根に関するQ&A

A house cannot be built without a roof but how much do you know about it? Here are questions and answers for kawara and roofs! Please refer these if you are looking to build a new house or renovate the roof, and don’t hesitate to contact us for any inquiries and quotations.

Q1:What is kawara?

Kawara is an incombustible roofing material made of natural clay by press molding, drying and firing it in a kiln with the inside temperature kept over 1,100 degrees.

Q2:What is Sansyugawara?

A generic term for high-quality clay roof tiles made in Mikawa, Aichi (Sansyu) area in Japan.

Q3:What is Sangawara we often hear?

Sangawara is a Japanese style roof which stems from how those aligned curves (sanyama) of a roof looked familiar with a frame of Japanese shoji. These days, in general, it is a term referring to kawara placed in the flat part of a roof, the most kawara used to cover the entire roof.

Q4:Is snow guard kawara needed?

It depends on the region. Snow guard kawara, as you can imagine from its name, is a kawara to keep snow on the roof. Here in Yamanashi we expect some heavy snow falls from time to time and it is used on many roofs to avoid damaging rainwater pipes and snow dropping in neighbor’s yard.

Q5:Can kawara be used on any roofs?

Recently there are kawara which can be placed on a 2.5+ sun pitch roof but in general, kawara can be placed on a roof that is steeper than 4 sun pitch but not on a roof less steeper than that. “Sun” can be expressed, in easy way, by the vertical measure when the horizontal length is 10cm. For example 4 sun pitch is equivalent to the angle of a resulting triangle when the vertical length is 4cm and the horizontal length is 10cm.

Q6:How long does a kawara last?

A clay kawara lasts almost permanently, longer than 50 years.

Q7:Is kawara healthy?

Kawara is made of natural clay which is recyclable and eco-friendly.

Q8:Is kawara eco-friendly?

Yes it is and it can be reused as various products. When turned into a road paver its moisturizing effect moderates the so-called heat island phenomenon, also no light reflection nor slip. Recycling kawara could result in reducing CO2. When turned into a wall material it helps to control humidity condition, and by spreading the broken ones on the floor, which looks nice by the way, it helps to drain better. But a broken kawara can be very dangerous. Please take extra care when you attempt to break kawara at home without having professionals around.

Q9:Is kawara roof cost efficient?

Some people say that kawara tiles are too expensive but that is not entirely true. Any roof materials require a maintenance about 20 years after an initial installation. Kawara is fired in a kiln and it won’t lose its color even when it gets old, but other materials require a re-painting with scaffoldings which can be costly. The initial cost for kawara is higher for sure than other materials but when you consider a total cost including the future maintenance kawara could be cost efficient.

Q10:Kawara tiles on my roof are unevenly colored.

Kawara tiles are made in the same way as fire ware by firing natural clay in high temperature. Subtle texture and glazing difference make the color of each kawara look different which makes the roof unique. If an entire kawara is glazed it gets almost all evenly colored. Color unevenness has become popular that it is nowadays made so on purpose.

Q11:No need for insulation material with a kawara roof?

Not true and insulation material should be used. Kawara itself has an insulating effect, the interspace between a sheathing roof board and kawara makes a layer of air which gets warmed up. The combination of an insulation material and kawara created even more insulating effect.

Q12:Should I be concerned for sick-house syndrome or asbestos?

Kawara is made of fired clay and there are no concerns for harmful substances. Glazed kawara is the same and there shouldn’t be any concerns for having harmful substances melted.

Q13:Is kawara resistant to acid rain?

Houses on the Sea of Japan side are known to have more damages from acid rain. It is also said that it is possible that houses are affected by the harmful substances flown from industrial districts in China. Kawara is resistant to acid rain as the glass layer created by glazing kawara exerts a strong acid resistivity.

Q14:Is a lighter roof better?

This is a common question we receive from our clients planning on renovating their houses. As we all know many houses were affected by the Great East Japan Earthquake but the seriousness of the damage differed depending on the age of each house. This is because Japan is an earthquake-prone country and the development of an architectural technology for earthquake protection has been expanding day by day. A lighter roof improves the earthquake resistance but not all the houses with it survived the earthquake. There were so many houses with kawara roofs survived as well. At any hand if you are looking for the best roof material it is as important to look for the house structure that fits. No matter how light the roof is, a house cannot be built by chopsticks.

Q15:How can I explain the image of a roof I want properly?

It is sometimes difficult to convey what you have imagined. Even a professional has a difficult time imagining how a roof would look by looking at a single kawara. There can be a trouble by starting a construction without knowing both a client and roofer did not understand each other. The best solution here is to identify what material you would like to use. If the magazine you found the kawara you liked listed the name of the manufacturer or material that would be perfect and if not find a house that is the closest to your imagination and have your roofer look at it. The worst thing which may result in inviting an unnecessary trouble would be to explain the image unclearly. It is important for a client and roofer to understand each other and have discussions until both are fully satisfied.

Q16:Can a sheet-metal or kesho-slate roof be changed to kawara roof?

The most important thing to consider here is the structure of the house. Sheet-metal or slate materials are lighter than kawara and it is possible that the house structure is not strong enough for a kawara roof. It is recommended to consult with the architect (for a new house), construction firm who built the house, or other professionals who can diagnose the house structure. The other important thing here is the inclination of the roof. The inclination needs to be steeper for a kawara roof than that for a sheet-metal or kesho-slate roof. You should have a roofer look at the inclination of the roof to determine if it’s suitable for laying kawara.

Q17:Is a leak only from a roof?

A leak does not necessary occur on a roof. Other possibilities are;
- Dead leaves stuck in a rainwater pipe
- Incomplete rainwater process in a balcony
- Other various causes such as a crack on an outer wall and the space between an old sash and wall

Q18:Can I fix the roof by myself?

Not recommended. First of all, a roofing work requires a dangerous high-place work and there is always a risk of a fall. It’s not just the roofing work but also any works should be done by professionals who have long experiences, knowledges and techniques. Not only you hurt yourself but also the roof gets damaged and it could be too late when you realized it was out of hand and decided to go to professionals. And it could be costly. Please call professionals for cost reductions, safety purposes and most of all, for your house.

Q19:Is a periodic diagnosis required?

Yes it is. Especially it is a must for a relatively old house. A roof is like a tooth. You know there’s something wrong but don’t want to do anything just yet. Eventually it could get out of hand which could turn into a huge problem that required a serious construction. Just like teeth roofs needs to be diagnosed periodically to have them last longer. Roofs protect the houses underneath and as long as there’s no leak the houses can last for a very long time. A house is a valuable property. We provide a free inspection service. Using the roofer like us will make your roof and house have a long happy life.

Q20:How do I find a good construction firm?

The way each firm does their job differs but in general, a good firm has a good relationship with local people and companies. A trust is the most important thing to earn for a firm. To value customers means to provide the jobs that we feel satisfied to. A very detailed information, communication with a client, enthusiasm for work and perfect job. A firm who can provide all of those is supposed to have a good reputation in the community. A long-established business in the community could be one of them as it wouldn’t be there for a long time if they had too many bad reputations. A recommendation from your neighbors who have had their houses constructed would be a good way to find one too. At any hand it is out of the question to select a firm that you don’t know when they started the business, where they are located and the reputation of. It is important to take time to research as many firms as possible regardless of the cost they offer and their recognition.