Insulation / kominka renovation in Toyama

Is an old house still cold after renovation?

No. But work that skimps on insulation is back where it started within a few years. Here is a project we did in Toyama, and where to start.

An old house is not cold if its insulation is done properly, and the cold returns within a few years if the work is cut back.
For the money, windows give the biggest effect, then the underfloor, then the ceiling.
Insulation costs from around ¥1 million for partial work such as inner windows, and ¥2–5 million for the whole house.
Our project used spray insulation and underfloor heating, took 2 months and cost ¥9 million in construction.
If the budget is limited, we insulate only the ground floor where you live, and do it properly.

The real project (2 months, ¥9 million)

Before

After

Spray-foam insulation, underfloor heating and two air conditioners went into the ground-floor living space and the upstairs tatami room. The owners' brief: "running costs matter more to us than the upfront cost". The result is a house whose temperature and humidity stay stable without running the air conditioning all year.

Construction period2 months

Construction cost¥9 million

Main worksSpray-foam insulation, underfloor heating, two air conditioners. Ground-floor living space and upstairs tatami room

What happens if you renovate fully and leave insulation for later

It looks just like new. It photographs well, too. But once you move in, it's stifling in summer, and in winter the room won't warm up even with the heating left running. It's miserable to live in. And by then the walls and floor are already finished, so redoing the insulation means tearing out the interior you just had done up.

We build full renovations and spec homes alike to the national long-life quality housing standard. Fittings and finishes can be changed later; insulation and structure can only be done at the start. Keeping that order also keeps the cost down.

A house is not finished when it is completed; handover is where it really starts. Not cold however many years you live there — that is what the work is for.

Why houses in Toyama are cold

High ceilings and big rooms: a lot of air to heat

Rooms open into each other with few partitions, so warm air doesn't stay put

Earth floors or strip foundations underneath, so the cold of the ground comes straight up

Big single-glazed sliding doors — windows lose the most heat

Bathroom and kitchen on the north side, frozen through

Gaps around the fittings. In a house of earthen walls and wooden doors, insulation alone won't stop the draughts

Where to start

By value for money: windows, then underfloor, then ceiling. Inner windows alone change how it feels, but if the underfloor is open the cold at your feet stays. On a tight budget, limit your living space to the ground floor and insulate that properly — it gets better results.

Insulation (inner windows, underfloor, ceiling / whole house)¥2–5 million

Partial insulation such as inner windowsfrom ¥1 million

About heat shock

In a Hokuriku winter, the gap between a warm living room and a cold hallway or changing room gets wide. If you'll be living with an older family member, narrowing that gap is the most important thing the work has to achieve. In fact, this is exactly why so many people decide on a full renovation when they start living with their parents.

FAQ

Do inner windows alone help?＋−

You will feel the difference. Windows lose the most heat, so inner windows first is the right order. But if the underfloor is open, the cold at your feet remains — if the budget allows, treat windows and underfloor as one package.

Do I need underfloor heating?＋−

Not if the insulation is done. Underfloor heating without insulation just keeps pushing up the energy bill. In our project we insulated first and then added underfloor heating.

Does it help in summer too?＋−

Yes. Insulation stops heat moving in either direction, so it works on winter chill and summer humidity alike. That is why renovations that skimp on it get called "muggy in summer".