In a small cabin, every draught feels personal. A gap under the door that would be a minor nuisance in a large house can cool a compact space within minutes, pushing your little stove or heater to work harder than it should. The good news is that cabins respond beautifully to careful draught-proofing. Because the spaces are small, the gains are quick to notice and the materials are inexpensive. The trick is to seal the gaps without sealing the air.

Why Small Cabins Are Different

A garden cabin has a much smaller internal volume than a house, so the same volume of cold air entering has a far greater effect on temperature. A single unsealed doorway can exchange the entire air content of a snug cabin several times an hour in windy weather. That constant turnover strips warmth from surfaces as well as air, making the space feel clammy and unwelcoming even when the heater is running.

Cabins also move. Timber frames expand and contract with the seasons, and a structure that sits on a slightly flexible base will shift through the year. Doors that fitted perfectly in July can develop a finger-width gap by January. Any draught-proofing you fit needs to accommodate that movement rather than fight it, which is why adjustable hardware tends to outlast rigid seals.

Start With a Survey, Not a Shopping List

Before buying anything, spend twenty minutes finding out where the cold is actually coming from. On a breezy day, run the back of your hand slowly around the frame of each door and window. You will often feel the draught before you see the gap. A lit incense stick or a thin strip of tissue held near a joint will also flutter and show you the path of the air.

• Check the bottom edge of doors first, as this is where most heat escapes.
• Look at the hinge side and the lock side, especially on outward-opening doors.
• Test window casements along all four edges, not just the opening side.
• Inspect any letterbox, keyhole, or cable entry, which are common hidden leak points.
• Note whether the frame itself is sound. Rot or a swollen sill needs fixing before any seal will work.

Brush Seals for Doors and Sliding Windows

Brush seals are the workhorse of cabin draught-proofing. A strip of dense bristles sits in a carrier that you screw or slide into a groove, and the bristles sweep against the moving surface. Because they flex, they cope well with the seasonal movement of timber and with doors that are not perfectly square.

For a standard cabin door, fit a brush seal to the bottom edge and, where there is a rebate, to the meeting stile. Choose a brush with a pile height that compresses slightly when the door closes. If the bristles barely touch, the seal will do nothing; if they are crushed flat, the door will drag. Sliding windows and patio-style doors benefit hugely from brush seals because the bristles glide rather than scrape.

Take care at the threshold. A brush seal alone will not stop a determined gale under a door that sits two centimetres above the floor. In that case, use a brush carrier combined with a small ramp or threshold strip so the bristles meet a solid surface.

Compression Strips for a Positive Seal

Where a window or door closes against a fixed frame, a compression strip gives a more airtight seal than a brush. These are usually hollow rubber or foam profiles that squash flat when the sash or door is closed, and they work best where the gap is consistent and the closing pressure is even.

Self-adhesive foam strips are the simplest option and are fine for lightweight cabin windows, but they can perish within a season or two in a sun-exposed position. A better long-term choice is a silicone or EPDM compression seal in a carrier that is pinned or stapled into a groove. These tolerate damp, UV and repeated compression far better.

• Clean and dry the surface before applying any adhesive strip, or it will peel within weeks.
• Mitre the corners or butt the strips neatly so you do not leave a gap at each join.
• Check that the strip does not prevent the window catch from latching properly.
• Test by closing a piece of paper in the gap. If it pulls out easily, the seal is too thin.

Adjustable Hinges and Hardware

Before adding seals, look at the hardware. Many cabin doors sag slightly or sit proud at one corner, and no amount of draught-proofing will help if the door itself is not closing squarely. Adjustable hinges allow you to move the door laterally and in and out, which lets you close up an uneven gap without planing or packing.

On uPVC or aluminium doors, the hinges and the lock keeps are usually adjustable with a hex key. On timber doors, a pair of adjustable butt hinges or flag hinges does the same job. Take the time to bring the door into even contact all round before fitting any seal. A well-hung door needs only a modest seal to become genuinely airtight.

Also check the keeps and strikers. Moving a striker plate a few millimetres can increase the closing pressure, which in turn makes a compression strip work properly. Small adjustments here often save you from buying a thicker seal.

Never Seal the Ventilation

This is the part that catches people out. A cabin needs a controlled supply of fresh air, particularly if it contains a wood burner, a gas heater, or anyone sleeping in it. Sealing every gap can make the space stuffy, cause condensation on cold surfaces, and in the worst case starve a combustion appliance of oxygen.

Keep any purpose-built vents clear, including trickle vents in window frames and air bricks in the wall. If your cabin has no ventilation at all, fit a small adjustable vent high on one wall and another low on the opposite wall so air can move through gently. Aim to seal the uncontrolled gaps while leaving a deliberate, controllable path for fresh air. The goal is a cabin that feels warm and still breathes.

Done carefully, draught-proofing is one of the most rewarding jobs on a small cabin. A few hours with brush seals, compression strips and a spanner will transform how the space holds its heat, and you will feel the difference on the very first cold evening.