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Close and lock the door, then use a thin strip of tissue paper to map air movement around the top, sides, threshold, keyhole and frame-to-wall joint. Fix loose hinges or a sticking door before adding seals. Measure the gap at several points and choose a seal whose working range fits the smallest and largest measurements without making the latch difficult to engage. Use a compatible compression seal at the jamb, and a brush, sweep, shoe or automatic drop seal at the bottom. Keep drainage, required ventilation, fire and smoke seals, accessible thresholds and door clearances intact. Test from both sides in wind and rain; draught-proofing controls unwanted air, but it must not trap moisture or replace intentional ventilation.
This guide is written for South Africa, Australia, New Zealand. Always check local codes, product specifications, licences, and site conditions.
Match the draught location to the right seal
A door normally has several different joints. Identify which joint leaks before buying a one-size-fits-all strip.
Top or latch-side gap
Tissue moves along the door stop, daylight is visible, or the seal no longer touches when the door is latched.
Next checkCheck alignment, then measure the closed gap and fit the specified compression, bulb, foam or V-profile seal.
Hinge-side gap
Air enters beside the hinges, or a new seal is crushed at one hinge and loose between them.
Next checkFix loose or proud hinges first. Use a thin, highly compressible profile that does not push the door out of alignment.
Gap below the door
Light, dust or a cold band appears over the threshold; the gap may vary across an uneven floor.
Next checkMeasure at several points and choose a sweep, brush, door shoe or automatic drop seal suited to the door swing and threshold.
Frame-to-wall crack
Tissue moves beside the architrave rather than between the door and stop; paint may crack along the frame edge.
Next checkInvestigate movement or water entry, then use a compatible flexible sealant at the correct joint—not weatherstrip on the door leaf.
Keyhole, letter slot or pet door
The perimeter seals well, but air, noise or light enters through a fitting in the door.
Next checkUse a purpose-made covered escutcheon, sealed letter plate or well-fitting pet flap without interfering with locks or safe escape.
Wind-driven rain at threshold
Water appears during exposed storms even after the air draught feels reduced.
Next checkTreat this as a weathertightness problem. Check sill falls, drainage, flashings and the complete door system rather than relying on an indoor brush strip.
Measure before buying weatherstrip
The best seal is soft enough to compress through the full gap range while leaving the door easy to close and lock.
- Confirm the door closes, latches and locks correctly. Repair binding, sagging or a damaged frame before adding pressure with a new seal.
- On a breezy day, use tissue paper around the closed door. Avoid candles or open flames near curtains, timber finishes, children or combustible materials.
- Measure the gap at the top, middle and bottom of both sides, across the head and under the door. Record the smallest and largest values.
- Identify the door material, opening direction, threshold type, exposure and whether existing seals are kerf-fitted, adhesive, pinned, screwed or integral to the frame.
- Check the product's working gap range, compression force, outdoor rating, UV resistance, paint compatibility and fixing instructions.
- Do not alter labelled fire, smoke, acoustic or security doors, shared-building doors or accessible entrances without the responsible specialist's approval.
Choose a seal that fits the joint
Use the table as a shortlist, then confirm the product instructions and actual measured gap.
| Leak location | Usually suitable | Main check |
|---|---|---|
| Top and vertical stops | Soft compression bulb, rubber or correctly sized foam | Seal contacts continuously without needing the door to be slammed |
| Variable side gap | Flexible V-profile or tolerant bulb profile | Working range covers both narrow and wide points |
| Smooth, even threshold | Flexible sweep or door shoe | Fin just contacts the sill through the full swing |
| Uneven floor or threshold | Brush or automatic drop seal | No snagging, trip hazard or blocked drainage |
| Frame-to-wall joint | Backing material and compatible flexible sealant | Movement, moisture and joint depth are understood first |
| Temporary internal zoning | Removable door snake | It is not relied on for exterior rain, smoke or security performance |
Step by step
Map every air path
Close, latch and lock the door as it is normally used. Move a light strip of single-ply tissue around the perimeter and note where it deflects. Check in more than one wind direction if possible. Look for moving curtains, rattles, dust trails and daylight, but remember that light can pass through a joint that does not leak strongly and air can travel behind architraves without visible light. Mark each leak with removable tape and distinguish the door-to-stop joint, bottom threshold, frame-to-wall joint and penetrations such as a keyhole or pet flap.
Correct operation before sealing
Open and close the door slowly and compare the reveal on every side. Tighten only sound hinge fixings, clean the threshold, remove folded old seals and confirm the latch draws the door consistently against the stop. If it rubs, will not latch, changes with wet weather or has diagonal gaps, use the related sticking-door guide first. Weatherstrip cannot straighten a warped leaf or frame; an oversized strip often hides the problem briefly while increasing closing force and wearing out quickly.
Remove failed seals carefully
Photograph the existing arrangement, especially corners and threshold transitions. Pull out kerf seals only as the manufacturer directs; soften adhesive residue with a surface-safe method and remove pins or screws without enlarging holes. Clean dirt, wax, oil and loose paint, then let the substrate dry. Preserve any separate rain-screen, drainage channel, smoke seal or intumescent component. If the old profile is proprietary, take an intact sample and door details to the supplier rather than substituting a visually similar strip.
Measure the working gaps
Measure with the door closed and latched at several points, because a nominal 4 mm gap may vary from 2 mm near a hinge to 6 mm at mid-height. A product labelled for the wrong range may either fail to touch or compress so hard that the latch, hinges and user carry unnecessary load. Also measure the door width and the bottom clearance across the full sweep. Check carpet, mats and changes in floor level on both sides before choosing a bottom seal.
Fit the head and side seals
Dry-fit each length and plan continuous corner contact. Follow the product orientation: many bulb and V seals work only when the moving leaf compresses them in the intended direction. Start on a clean, dry surface at the hinge side or as instructed, press adhesive strips without stretching them, and pin or screw mechanical carriers into suitable material. Butt or mitre corners as specified so small openings are not left at the top. Keep seals clear of hinges, latches, multipoint keeps and drainage routes.
Fit the bottom seal
Select a brush for tolerant contact over a slightly irregular surface, a flexible sweep for a smooth sill, a door shoe where both faces can be covered, or an automatic drop seal when clearance must remain during the swing. Cut the carrier square, finish sharp edges and position it so the fin or bristles just make continuous contact when closed. Predrill where the door material requires it. Never create a trip edge, obstruct a wheelchair route, seal over threshold drainage or puncture a door where its construction or warranty prohibits fixing.
Seal stationary frame joints separately
If air is coming between the frame and wall, weatherstrip on the leaf is the wrong material. Check for loose architraves, growing cracks, dampness and exterior seal failure. Small stable internal joints may accept a flexible paintable sealant; deeper joints need the correct backing and joint geometry. Exterior openings must manage water as a complete system, so recurring rain entry, rot, corrosion or movement needs a door installer or building professional before cosmetic caulk is added.
Test closure, ventilation and weather
Operate the door at least ten times from both sides. It should latch and lock without shoulder pressure, the lever should return, and the seal should contact without tearing or rolling. Repeat the tissue test and inspect corners. During the next exposed rain, check the sill and adjacent finishes without blocking weep paths. Maintain intentional ventilation: kitchens, bathrooms, combustion appliances and whole-home systems still need designed air supply and extraction. Recheck high-use adhesive seals periodically and replace them when crushed, brittle or detached.
Expert tips
- Buy by measured working range, not by the thickest-looking profile. Excess compression is a common reason a newly sealed door will not latch.
- Use tissue rather than a naked flame to find draughts; it is safer and can reveal small air movement clearly.
- Air sealing and rain sealing are related but different jobs. An interior brush may stop a cold draught yet do nothing for wind-driven water.
- Do not seal purpose-made vents, exhaust outlets, fireplace air supplies, door undercuts required by a ventilation design, or drainage openings.
- A door snake is useful for temporary internal zoning but moves when the door opens and is not a durable exterior threshold solution.
- Keep the product label and a short offcut so the profile and size can be matched accurately when replacement is needed.
Common questions
How do I find where a door draught is coming from?+
Close and latch the door, then move a thin strip of tissue around the head, sides, bottom, frame-to-wall joint, keyhole and other fittings. Mark movement with removable tape. Repeat in different wind conditions and distinguish air through the opening joint from air leaking behind the frame.
Why will my door not close after adding weatherstrip?+
The profile is probably too thick, installed on the wrong contact face, stretched, folded at a corner, or compensating for a misaligned door. Remove the added pressure, correct hinges and latch alignment, measure the closed gap at several points and choose a softer seal with the correct working range.
What is best for a draught under an external door?+
It depends on the threshold. A flexible sweep suits a smooth even sill, a brush tolerates small variations, a door shoe wraps the bottom edge, and an automatic drop seal retracts while the door moves. The chosen seal must not block drainage, catch the floor, create a trip hazard or prevent locking.
Can I use silicone around the moving edge of a door?+
No. The opening joint needs a purpose-made compressible weather seal. Flexible sealant is for suitable stationary joints such as a stable gap between frame and wall. Applying sealant across moving parts can glue the door, damage finishes and obstruct drainage or hardware.
Will draught-proofing cause condensation or mould?+
Draught-proofing removes uncontrolled leakage; it does not remove the need for deliberate ventilation. Continue using extract fans and designed vents, manage indoor moisture and open windows when appropriate. If condensation increases, review moisture generation, heating and the whole ventilation strategy rather than removing one useful door seal at random.
When should a professional seal the door?+
Use a specialist when the door is fire-, smoke-, acoustic-, security- or weather-rated; part of an accessible route or shared building; badly warped; leaking rain; or fitted with a multipoint lock or proprietary seal. A professional should also assess growing frame cracks, rot, corrosion and suspected structural movement.
Sources & further reading
We link to official building-code, government and public-health material where a technical or safety claim needs authoritative context. Local rules and adopted code editions can change.
- Australian Government Department of Climate Change, Energy, the Environment and WaterInsulation and draught proofingOfficial Australian guidance on detecting unintended air leakage, fitting door seals and retaining appropriate ventilation.↗
- YourHomeVentilation and airtightnessAustralian technical guidance distinguishing controlled ventilation from unwanted infiltration and matching seal types to openings.↗
- New Zealand Building PerformanceStopping draughtsOfficial New Zealand advice on finding draughts, repairing hardware first, measuring gaps and choosing foam, rubber, V or brush seals.↗
- BRANZDraught control systems for New Zealand housesBuilding-research findings on compression force, variable gaps, threshold durability and the separate functions of air and rain seals.↗
- Builders South AfricaHow to draft seal your doorSouth African DIY demonstration used to cross-check local terminology, product availability and homeowner installation intent.↗
- HomeTipsDoor weather stripping: how to seal out draftsEstablished how-to reference used for content-gap analysis and practical cross-checking of jamb seals, sweeps, shoes and thresholds.↗
Stop if the work involves structural uncertainty, hazardous materials, heights, live services, gas, serious water damage, or regulated work. Local rules differ—use an appropriately licensed professional where required.