Key Takeaways
Why Draught-Proofing Matters
Unwanted gaps in a home's envelope — the boundary between conditioned indoor air and the outdoors — allow cold air to seep in during winter and warm air to escape. The result is a room that never quite reaches a comfortable temperature, a heating system that works harder than it needs to, and energy bills that reflect both. Draught-proofing addresses this by physically blocking the pathways air travels through.
Unlike insulation upgrades or new windows, draught-proofing is a category of improvement accessible to almost anyone. Most materials cost just a few dollars per meter, and the techniques involved are genuinely beginner-friendly. It is often cited by energy efficiency bodies as one of the highest-impact, lowest-cost interventions available to households. For renters as well as owners, the majority of draught-proofing work is reversible, making it practical even in a leased property — though checking with your landlord first is always wise.
This guide walks through every stage of the process: finding gaps, selecting materials, applying them correctly, and making sure the result doesn't inadvertently compromise indoor air quality.
Finding Where Cold Air Gets In
A systematic inspection is the most important step. On a cold, windy day, move slowly around the home and hold your hand near suspect areas — you can often feel moving air without any equipment at all. A lit incense stick (or a thin strip of tissue paper) held near a gap will visually confirm airflow: the smoke or paper will deflect toward or away from the gap.
The most productive places to check include:
- Exterior door frames — the gap between the door edge and the frame is a common culprit, especially in older homes where wood has warped over time.
- Letter boxes and keyholes — these are often overlooked but can allow a surprising amount of air movement.
- Window frames and sashes — particularly single-pane or older double-hung windows.
- Floorboard gaps — especially on ground floors where air can enter from a sub-floor void.
- Skirting boards — where boards meet the wall, gaps often develop as a house settles.
- Loft hatch edges — frequently ignored but potentially significant given that warm air rises.
- Service entry points — where pipes, cables, or ducts pass through external walls.
Make a simple sketch or list as you go. It helps prioritize which gaps to address first and prevents you from buying far more material than you need.
Test door weatherstripping by closing the door on a thin piece of paper — you should feel resistance when pulling the paper out. If it slides freely, the strip isn't making firm contact and won't seal effectively.
Even well-installed foam strips can miss the mark if the gap profile isn't matched correctly to the product. This simple paper test is used by building performance assessors to verify seal quality without specialized equipment.
Inspect and replace foam weatherstripping every two to three years — compressible foam loses its memory over time and stops forming an effective seal even when it looks intact.
Foam degrades with repeated compression cycles and UV exposure. Aged strips that appear visually fine often no longer spring back enough to make contact across the full door frame, making periodic replacement a key part of maintaining draught-proofing.
Choosing the Right Sealing Material
Different gaps call for different products. The three main categories cover most situations a first-timer will encounter:
- Self-adhesive foam strips (weatherstripping)
- Best for door and window frames where two surfaces compress against each other when closed. They come in various profiles (P-shaped, D-shaped, E-shaped) to suit different gap sizes. Check the gap width before purchasing — compressible foam that is too thick won't allow the door to close properly.
- Silicone or acrylic sealant (caulk)
- Ideal for static gaps that don't open and close — such as where a window frame meets the wall, or around pipe penetrations. Silicone remains flexible over time and handles some movement; acrylic can be painted over. Apply with an inexpensive caulk gun.
- Door brush strips and threshold seals
- Fitted to the bottom of exterior doors to seal the gap between the door base and the threshold. Brush strips allow the door to sweep freely; compressible threshold seals form a tighter seal but require the door to be adjusted carefully to avoid binding.
For floorboard gaps, a flexible filler or specialist floor gap filler is appropriate — standard caulk may crack with seasonal movement of the timber. See our guide to repairing surfaces without a contractor for related material selection advice.
How to Seal Doors and Windows
Before applying any sealing material, clean the surface thoroughly. Adhesive foam strips will peel away within weeks if applied to dusty or oily frames. Wipe the rebate (the groove or lip the door or window closes against) with a damp cloth and allow it to dry completely.
Applying weatherstripping to doors
- Measure the full perimeter of the door rebate you intend to seal — top, two sides, and optionally the bottom if no threshold seal is fitted.
- Cut foam strips to length with scissors, leaving a clean butt joint at corners rather than overlapping.
- Peel the backing and press the strip firmly along the rebate so that the door compresses it when closed. Close the door to check resistance — you should feel light, even pressure, not a stiff push or a gap.
- For the door bottom, measure the door width, cut a brush or threshold strip to length, and screw it to the door face following the manufacturer's guidance.
Sealing window frames with caulk
- Cut the caulk tube nozzle at a 45-degree angle to a size matching the gap width.
- Load the tube into a caulk gun and apply a smooth, continuous bead into the gap between the window frame and surrounding wall.
- Smooth immediately with a wet finger or a caulk tool for a neat finish.
- Allow to cure per the product instructions before painting over acrylic types.
For a broader look at window and door maintenance, our weathertight homes guide covers additional techniques.
Do Not Seal Ventilation Designed to Protect Appliances
Gas appliances, open fireplaces, and solid-fuel stoves require an adequate supply of combustion air. Blocking air bricks or vents near these appliances can be dangerous. If in doubt, consult a licensed heating or gas professional before sealing anything in proximity to a fuel-burning appliance.
Floors, Loft Hatches, and Overlooked Gaps
Ground-floor floorboards in older homes frequently have gaps between boards that allow cold air from the sub-floor to enter the room. A flexible sealant or purpose-made floor filler pressed into the gaps handles this well. For very wide gaps or a large floor area, thin rope-style filler (sometimes called draught-excluding rope) can be pressed into the gaps with a blunt tool and painted over. Don't use rigid fillers — timber expands and contracts with humidity, and a rigid material will simply crack out.
Skirting boards can be caulked along the bottom edge where they meet the floor, and along the top edge where they meet the wall, to block the path air takes from the sub-floor void into the room.
Loft hatches deserve specific attention. Warm air rises, and a poorly sealed hatch allows it to escape directly into the roof space. Self-adhesive foam strip around the hatch frame, combined with a layer of rigid insulation board fixed to the top of the hatch panel itself, addresses both draught and heat loss at the same time.
Service penetrations — where plumbing pipes or electrical conduits pass through external walls or floors — should be sealed with a fire-rated flexible sealant where they pass through anything acting as a fire barrier. In all other locations, standard silicone is appropriate. For further guidance on structural maintenance priorities, see our seasonal home maintenance checklist.
Balancing Draught-Proofing with Ventilation
A common concern — and a legitimate one — is that sealing gaps too aggressively will trap moisture and pollutants indoors. In well-ventilated modern homes this is rarely an issue; in older homes that rely on uncontrolled air infiltration as their primary source of fresh air, the concern warrants attention.
The principle to follow is straightforward: seal uncontrolled gaps (those that occur by accident, such as around frames and floorboards), but preserve or improve controlled ventilation (purpose-built vents, trickle vents in window frames, and extractor fans in kitchens and bathrooms). Never block:
- Air bricks or sub-floor ventilation vents — these protect timber floor joists from moisture damage
- Trickle vents on window frames — small openings deliberately built into the frame
- Chimney flues serving active gas appliances — always consult a qualified professional before interfering with any flue
If you're concerned about indoor air quality after draught-proofing, ensuring bathroom and kitchen extractors are working well, and running them during and after cooking or bathing, is an effective and proportionate response. Our ventilation and airflow guide explains controlled ventilation in more detail.
Draught-proofing done thoughtfully is a straightforward, rewarding project. Combined with the small upgrades that change how a room feels, it forms the practical foundation of a more comfortable, efficient home — one improvement at a time.