New build family home for Mr. Y in Yokosuka

–  Building a post and beam house using traditional Japanese construction methods –

Part 3: Foundation work

So, with the purification rituals out of the way and the Gods given their dues, it is now time to get on with the business of laying the foundations.

Even though the house will be built with traditional Japanese carpentry techniques, the foundation itself is generally made from re-enforced concrete. Traditionally, Japanese building foundations were large natural stones on which the structural pillars stood. This technique is called Ishibadate （石場建て）and sometimes we still use it today, but that is a blog entry for another time.

As I’m sure you know, the foundation is basically the concrete base on which the wooden structure sits. We build the foundation and drop the house on top, so to speak.

But first things first. We need to determine a level and this process is called the Mizumori-yarikata （水盛りやり方）.

We do this by placing upright wooden stakes called Mizukui （水杭）around the perimeter of the building site and then we attach a wooden board called a Mizunuki  （水貫）on one of the stakes. Using a laser-level we mark out the level on the Mizukui and Mizunuki. The level written on the Mizunuki is very important as this will be the reference point for all future surveying activities.

With the levels marked out, the concreters now have line to work from and can commence the site excavation in preparation for laying the concrete foundation.

Meanwhile, the carpenters go back to the workshop and get on with marking out the timber and cutting the joints…

横須賀市Y様邸新築工事

〜伝統構法で造る木組みの家〜

Part 3: 基礎工事

さあ！地の神様に工事の安全と家族の繁栄をお願いする儀式［地鎮祭］を終えるといよいよ基礎工事が始まります。基礎とは家を支えるコンクリートのかたまりのことです。地盤の上にまずコンクリートのかたまり（基礎）をおき、その上に建物がドーン！って乗っかるのです。

まずはじめに［水盛やり方］をします。家の外周に水杭（みずくい）を打ち込み、それに 水貫（みずぬき）という木の板を水平に取り付けていきます。そしてその板に建物の基準となる線や情報を書き込んでいくのです。これらの作業を［水盛やり方］といいます。

この［水盛やり方］を頼りに鳶さんが地面を掘ってコンクリートの基礎をつくっていきます。一方で大工部隊は作業場で［墨つけ・刻み］を行なっています。