Roof and snow / Hokuriku kominka

A lighter roof works against snow and earthquakes at once.

In Hokuriku an earthquake can strike with snow on the roof. Snow measures and seismic measures are therefore one question. Here is why we start from the roof.

Re-roofing with a lighter material handles snow and earthquakes at the same time.
In Hokuriku, an earthquake can strike while snow is lying on the roof.
Re-roofing costs about ¥2–4.5 million, and seismic reinforcement about ¥2.5–7 million.
Roof work needs scaffolding, so combining it with seismic reinforcement and other work saves money.
If you keep the tiles, we decide the amount of seismic reinforcement on the basis that the roof is heavy.

When repairing a Hokuriku kominka, the roof cannot be avoided. It carries the snow, it is where leaks begin, and it decides the forces on the building in an earthquake. Leave it for later and the interior you made good will deteriorate within a few years.

The tiled roof of a Hokuriku townhouse (Kanazawa) — Photo: LordAmeth "Roofing at Shima"(CC BY-SA 3.0), cropped

Three problems the roof carries

Weight. Tiles laid on earth add up to several tonnes on their own
Snow. Add snow, and the load on the building rises further
Earthquakes. The heavier the roof, the greater the force on posts and beams when it shakes
Leaks. They start at the valleys and ridge, and by the time you notice, the roof framing is damaged (how water reaches the frame, and selling without repairing)
Snow clearing. For elderly family it is a heavy burden in cost and danger
Falling snow. Snow sliding onto the neighbours or the road causes disputes

Lighten it, and two problems go at once

Re-roof from tiles to a lighter material, and the weight on the building goes down. This is both a snow measure and a seismic measure at once. In Hokuriku, an earthquake can strike while snow is still sitting on the roof, so snow measures and seismic measures can be thought through together in one job.

If you are considering re-roofing, combining it with seismic reinforcement improves the value. Both need scaffolding, so doing them together is cheaper.

Righting a house whose posts have leaned and beams sagged under snow is explained in How to fix a leaning house.

Not clearing the snow

Rearranging the snow guards, changing the roof's shape and pitch, installing snow-melting equipment. There are several options. But which one suits the house depends on how it's built and its relationship to the neighbouring land, so we decide after seeing the site. Snow-melting equipment in particular carries an electricity bill every year you live there — not a decision to make on initial cost alone. Leave a roof that sheds snow toward the neighbouring land as it is, and it becomes the owner's liability (Who is liable if a vacant house harms the house next door).

Snow clearing and pipe draining for a house left empty over winter: see the year-round calendar for looking after a vacant house from afar. What to do when the roof has already collapsed is covered separately.

Cost guide

Re-roofing (tiles, snow measures)¥2–4.5 million
Seismic reinforcement (walls, hardware, foundation)¥2.5–7 million

* Construction cost. Varies with area, roof shape and scaffolding conditions. Land and building purchase not included.

Roof first

If you can't put together a budget for a full renovation right away, one approach is to do just the roof and seismic reinforcement first and leave the interior for a few years later. Do it the other way round — finish the interior, then the roof — and a leak can stain the ceiling you just had done. Getting the order right is what keeps the cost down in the end.

FAQ

I want to keep the tiles.＋−

You can. Keeping the tiles to match the local townscape is a valid choice. We then size the seismic reinforcement for a heavy roof. Lighten the roof or add reinforcement — we tell you which suits the house after seeing it.

Can you tell from outside whether it leaks?＋−

Often from stains on the ceiling or discoloured posts in the roof space. But water travels unexpected routes, so the cause is not always directly above the stain. At the survey we look at the roof from above and the roof space from inside.

Can I ask for roof work only?＋−

Yes. But since it needs scaffolding, doing the exterior walls, gutters or some insulation at the same time gives better value. If you plan to do them anyway, combining them ends up cheaper.

Start from the roof

We come and look at the roof.

The site survey is free. We check the roof space too and tell you what work is needed.

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