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What is weatherboard cladding?

The Wood Guide · Choosing and comparing

Buying guide

Weatherboarding

Overlapping boards that together form a watertight skin. A technique from shipbuilding that still produces the most beautiful façades.

  • Swedish · shiplap · double
  • Always horizontal, overlap facing down
  • Larch and Douglas fir are the standard
weatherboards
Weathered weatherboards overlapping horizontally
Weathered weatherboards overlapping horizontally
New wooden weatherboard façade next to corrugated sheeting and a window
New wooden weatherboard façade next to corrugated sheeting and a window
Summary

Weatherboard at a glance

Also called cladding boards or feather-edge boards: wooden boards with a tapered edge, designed to overlap one another and together form a water-shedding layer.

The principle comes from early shipbuilding and traditional Scandinavian architecture: lay boards so that each board overlaps the previous one, and water runs from one to the next without ever reaching a joint. No sealant, no membrane — just gravity and shape.

That makes weatherboarding one of the few cladding systems that protect themselves. It also means that one fitting mistake — the overlap the wrong way round — makes the whole system worthless.

The rule that decides everything

The thick edge goes at the bottom, the thin one at the top, and each board overlaps the board below it on the outside. That way water runs outwards. Fitted the other way round, it runs behind the cladding and the façade rots from within — a mistake you only see after years.

What it is
overlapping profiled cladding boards
Origin
shipbuilding and Scandinavian architecture
Types
Swedish (feather-edge), shiplap, double
Common species
larch, Douglas fir, western red cedar, thermally modified wood
Fitting
horizontal, overlap outwards and downwards
Essential
a ventilated cavity behind the boards

To be fair: weatherboarding needs a ventilated cavity. If you screw the boards directly onto a closed surface, you trap moisture between wood and wall, and then even durable wood rots within a few years. The battens behind the cladding are not an extra but half the system.

In pictures · where does the water go?

The overlap

Behind the boards

The profile

How it lasts for decades

  • Vertical battens on the wall: a cavity of at least 20 mm.
  • Leave the bottom and top open; an insect mesh keeps pests out.
  • Work from the bottom up, with the spirit level on it every few rows.
  • One fixing per board per batten, always stainless steel — two screws stop the board from moving.
  • Every sawn end gets a coat before fitting.

Which wood

Larchclass 3resinous, honey brown, greys beautifully
Douglas firclass 3reddish brown, calm appearance
Western red cedarclass 2very light, the most durable of the softwoods
Thermally modified woodclass 2–3deep brown right through, without chemicals
Pressure-treated spruceuse class 3the most affordable option
Irokoclass 1–2exceptionally stable, tropical
Larch: the standard for weatherboard →
Who's who

Three profiles, three faces

Swedish weatherboard (feather-edge boards)

Thicker bottom, thinner top. Gives a robust, strongly overlapping look with plenty of shadow. The classic for fences and rustic façades.

Shiplap weatherboard

Straight top with a sloping groove on the underside. Cleaner and flatter in appearance — the choice for contemporary architecture.

Double weatherboard

Profiled on both sides, so the boards interlock more deeply. More material, but also a stronger water barrier.

The look you get

Swedish weatherboard gives deep shadow lines and a lively façade; shiplap a calm, almost flat surface. That difference is greater than the profile suggests.

Choice of material

Which wood species for weatherboard

Species Class Character Price
Larch 3 Resinous, warm honey brown, greys beautifully Mid-range
Douglas fir 3 Reddish brown, calm appearance Mid-range
Western red cedar 2 Very light, the most durable of the softwoods High
Thermally modified wood 2–3 Deep brown right through, without chemicals Mid to high
Pressure-treated spruce use class 3 The most affordable option Entry level
Iroko 1–2 Exceptionally stable, tropical High
Why larch and Douglas fir dominate

Both reach durability class 3 without impregnation, they are available in long lengths, and water runs off them naturally. For a façade class 3 is more than enough — after all, it doesn't stand in the ground.

In practice

How it lasts for decades

  1. Battens firstVertical battens on the wall, so that a ventilated cavity of at least 20 millimetres forms behind the cladding.
  2. Leave the bottom and top openAir must be able to get in at the bottom and out at the top. An insect mesh keeps pests out without blocking ventilation.
  3. Work from the bottom upThick edge at the bottom, each board overlaps the previous one on the outside. Check with a spirit level every few rows.
  4. One fixing per board per battenTwo screws through the same board stop it from moving, and then it splits. Stainless steel, always.
  5. Treat the end grainEvery sawn end gets a coat before fitting. That is where moisture gets in fastest.
Maintenance, or rather not

Untreated weatherboard in larch or Douglas fir turns silver grey within two years and then lasts for decades without a single coat. If you want to keep the warm colour, that is a choice for yearly maintenance — not a necessity.

Quick answer

Frequently asked questions about weatherboard

What is the difference between Swedish and shiplap weatherboard?

Swedish weatherboard (feather-edge) has a thicker bottom and a thinner top, which gives strong shadow lines. Shiplap has a straight top with a groove on the underside and looks clean and flat.

Which way should the overlap face?

The thick edge at the bottom, and each board overlaps the board below it on the outside. That way water runs outwards. Fitted the other way round it runs behind the cladding — the most common and most expensive mistake.

Does weatherboard need a cavity behind it?

Yes, always. At least twenty millimetres, open at the bottom and top. Without ventilation, moisture stays between wood and wall and even durable wood rots away.

Which wood is best for weatherboard?

Larch and Douglas fir are the standard: class 3, long lengths and they grey beautifully. Western red cedar is the more expensive top choice.

More in The Wood Guide

Weatherboard in perspective

A façade that protects itself — as long as the overlap faces the right way.

To The Wood Guide Larch Thermally modified wood

Have a question about your project? Just ask — we're happy to help.

Photos via Wikimedia Commons: Weathered weatherboards overlapping horizontally — Daniel Case, CC BY-SA 3.0 · New wooden weatherboard façade next to corrugated sheeting and a window — Jiri Lev, CC BY-SA 4.0

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