The cabin, layer by layer
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How a typical cabin is built
Every cabin is different, but the build-up below usually follows the same principle. Curious about yours? We are happy to do an informal site visit.
The roof · Roofing, ventilation, insulation and ceiling
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Roofing
Timber, turf or slate. The outermost layer against the weather.
It pays to check the junctions around the chimney, roof windows and valleys. That is where water most often finds its way in.
Did you know? A timber roof can last for decades, as long as it can breathe and dry out.
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Battens and ventilation
Ventilates moisture away from under the roofing.
Worth checking: that the roof is well ventilated. Lots of icicles at the eaves can mean the ventilation needs improving.
Did you know? Icicles at the eaves are often a sign that heat is escaping and melting the snow.
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Roof underlay
The second barrier against water.
On older roofs it is wise to check the condition of the underlay. It ages, and some cabins do not have one at all.
Did you know? The underlay catches the water that drifting snow and driving rain push in under the roofing.
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Rafters and insulation
Carry the roof and keep the heat in.
Common in older cabins: 50–100 mm of insulation. Adding insulation to the roof is often very effective.
Did you know? Warm air rises. That is why most heat escapes through the roof.
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Vapour barrier
Stops moist indoor air.
It pays to check that the vapour barrier is intact and airtight, especially around penetrations.
Did you know? Cooking, showering and breathing produce several litres of water vapour a day. It must not get into the roof.
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Ceiling
The inside of the roof.
Worth keeping an eye on: discolouration in the ceiling can be an early sign that something higher up should be checked.
Did you know? Brown rings in the ceiling almost always mean water from above.
Exterior wall · Cladding, wind barrier, insulation and panelling
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Exterior cladding
The first line of defence against wind and weather.
It pays to check the lowest part of the cladding, especially where it is close to the ground.
Did you know? Vertical cladding sheds water faster than horizontal cladding.
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Battens and air gap
Lets the cladding dry out from behind.
Common in cabins from the 70s and 80s: cladding without an air gap. It is easy to check when the cladding is being replaced anyway.
Did you know? The air gap is no thicker than a batten, but it is essential.
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Wind barrier
Stops draughts getting into the insulation.
If you notice draughts or cold walls, the wind barrier is a natural place to start.
Did you know? The wind barrier works like a good outdoor jacket: windproof, but breathable.
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Timber frame and insulation
Carries the wall and keeps the heat in.
Common in older cabins: 50–100 mm of insulation. The wall can often be insulated further along with new cladding.
Did you know? Insulation works because it holds still air.
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Vapour barrier
Stops moist indoor air.
It pays to check that the vapour barrier is airtight around windows and power sockets.
Did you know? The vapour barrier is the opposite of the wind barrier: it stops vapour from the inside.
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Interior panelling
What you see and touch.
The panelling tells you little about what is behind it. If we see signs of damp, we take a look behind.
Did you know? A small hole behind a power socket can let out a surprising amount of moist air.
Windows · Glazing, condensation, wall position and linings
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Sealing and flashing
Packing, tape and flashing around the window.
Worth checking: the junction between window and wall. It often matters more for draughts than the window itself.
Did you know? The flashing above the window leads water out. Without it, water runs into the wall.
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Frame and sash
The frame is fixed to the wall, the sash holds the glass.
On original windows from the 70s and 80s it is wise to check the bottom of the sash and frame.
Did you know? A window does not just sit in a hole. Its position in the wall decides how airtight it will be.
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Double or triple glazing
Sealed units with two or three panes and gas in between.
Common in older cabins: double glazing. Modern triple glazing keeps the heat in several times better.
Did you know? Triple glazing gives a warmer inner pane, so you avoid cold draughts when sitting by the window.
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Condensation
Mist and ice on the glass.
Condensation on the inside means a cold glass surface or a lot of moisture indoors. Condensation between the panes means the sealed unit has failed.
Did you know? Mist on the outside of new triple-glazed windows in the morning is a good sign. The glass insulates so well that the outer pane gets cold.
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The window in the wall
When the wall is insulated, it gets thicker.
If you add insulation without replacing the windows, they end up deep inside the wall. That gives deep reveals, a cold bridge around the frame and difficult sealing.
Did you know? The window should sit in the same layer as the insulation and wind barrier, otherwise it gets cold around the frame.
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Linings and trim
Interior boarding around the window, with trim.
If you replace the windows a few years after the renovation, linings, trim and often panelling must be removed and redone. That is twice the work.
Did you know? Doing the windows together with the renovation means you pay for removal, linings and trim once. It can also be planned in stages.
Floor and crawl space · Flooring, joists, crawl space and foundation
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Floor covering
Parquet, solid wood or tiles.
Creaking is rarely serious, but a floor that gives underfoot is worth a closer look.
Did you know? A creaking floor is rarely serious, but it tells you something about what is underneath.
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Subfloor
Provides a flat and stable base.
Worth looking for: uneven or swollen boards can point to past moisture.
Did you know? Chipboard that has been wet swells and never becomes completely flat again.
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Floor joists and insulation
Carry the floor and keep the heat in.
Cold floors are common in older cabins, and often easy to improve from the crawl space.
Did you know? The joists stand on edge because they carry much more that way.
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Wind barrier
Stops draughts from below.
Common in older cabins: no wind barrier under the floor. It is often a simple improvement.
Did you know? Much of the draught in older cabins actually comes from below, through the floor.
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Crawl space
Ventilated space under the floor.
It pays to check that the crawl space is dry and well ventilated. This is where we most often recommend measures.
Did you know? In summer, warm and humid outdoor air can cause condensation in a cold crawl space.
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Foundation
Carries the whole cabin.
Worth looking for: cracks and settlement in the foundation walls, and whether the foundation is frost-protected.
Did you know? Frost in the ground can lift a foundation that is not frost-protected.