Door Draught Proofing Guide: Seals, Gaps and Thresholds UK

A cold draught around a front, back or internal door can make a room uncomfortable, but the answer is not always to buy the thickest weather strip. Different gaps need different solutions, and the wrong seal can make a door difficult to close, reduce security or interfere with fire and ventilation requirements. This UK buying guide explains the common causes of door draughts, how to identify the leak, what seal profiles and thresholds do, and when a replacement component is worth the cost. It also covers door alignment, external weatherproofing, smoke seals and maintenance so you can avoid quick fixes that create new problems. Start with our door accessories selection and compare individual product details before making changes.

Start by finding where the draught enters

A draught around a door is not always caused by the door leaf itself. Air can pass between the frame and masonry, through worn weather seals, beneath a threshold, around letterplates or through a poorly adjusted latch. Fixing the wrong component may leave the problem unchanged. Start by observing where the movement of air is strongest on a windy day and checking for visible daylight around the closing edges.

A piece of tissue held near the perimeter can help locate movement, but avoid treating this as a laboratory test. Check several points around the frame and note whether the door still closes evenly. If the sash or leaf has dropped on its hinges, an adjustment or repair may be more effective than adding an oversized seal. Serious moisture penetration or structural distortion needs professional assessment, not just self-adhesive tape.

Different door seals explained

Compression seals work by closing against the frame, while brush-style seals can accommodate some movement and are used in certain draught-excluding applications. Rubber and other elastomer seals may be designed to fit grooves rather than attach to flat surfaces. Each profile has a different compression range, so choosing by appearance alone can create a seal that is too loose or prevents the door from latching.

Before buying, inspect the existing seal's cross-section and fitting channel. Photograph the profile against a ruler and compare the manufacturer's dimensions. A slightly thicker seal is not always better; excessive compression can strain hinges and locking points. Browse relevant door accessories and make sure the seal material is appropriate for an exterior or interior location as required.

Bottom-of-door gaps and thresholds

The gap beneath a door can account for a noticeable draught, especially where the interior floor level has changed after replacing carpet with hard flooring. Options include suitable brush strips, drop seals and purpose-designed thresholds, but the correct solution depends on the door type and accessibility requirement. External thresholds must also manage rainwater, so draught control must not interfere with drainage.

Measure the gap with the door closed and check how it changes across the width. An uneven floor or poorly aligned leaf can make a single fixed-depth strip ineffective. In kitchens, bathrooms or other spaces requiring ventilation transfer, closing every air path may be inappropriate. Fire doors can also have specified undercuts and seals. Follow the relevant manufacturer and building guidance before fitting a bottom seal.

Exterior doors: weatherproofing and security together

For an outside entrance, weather resistance and secure locking need to work together. If the lock pulls the door too loosely against the frame, the seal may fail to compress. If it pulls too tightly, the handle can become difficult to operate. Hinges, keeps and multipoint locking points should be checked against the door maker's adjustment guidance.

A damaged cill or missing perimeter weather strip can allow wind-driven rain as well as air to enter. Inspect the frame corners and sill joints, particularly on exposed elevations. If there are repeated leaks, seek an installer who can assess the whole external doorset. Explore external door options if an older assembly has deteriorated beyond economical repair rather than repeatedly replacing small components.

What about interior doors?

Internal doors rarely need the same heavy weather seals as front or back doors, but limiting unwanted air movement can improve comfort between heated and less-heated zones. It may also reduce some sound leakage, particularly around the perimeter. However, an ordinary seal does not create a certified acoustic or fire-rated assembly.

Think about door function before closing gaps. Bathrooms and kitchens may rely on planned airflow, and certain ventilation systems need transfer paths between rooms. A door that rubs heavily after seals are added may suffer faster wear and become difficult to close. Choose a low-profile, suitable product only once you've checked the door movement and room ventilation requirements.

Door hinges and alignment checks

A door with worn or loose hinges can drop far enough for the closing edge to move away from the frame seal. Before adding new strips, inspect screw fixings, hinge condition and whether the leaf is twisted. A bowed door may need specialist attention, while a loose hinge might be rectified by suitable repair work to the lining.

Heavier doors need appropriately rated hinges and secure fixing into sound material. Repeated tightening of screws into stripped holes is not a durable repair. Check door hinges for compatible replacements and refer to the door manufacturer's installation instructions. If the issue affects a fire door, ask a competent specialist to assess any proposed alteration before work proceeds.

Intumescent strips are not standard draught seals

Fire protection strips and ordinary draught-excluding products serve different purposes. Intumescent material expands at elevated temperatures to help seal a fire-door perimeter as part of a tested assembly. Smoke seals may limit the passage of cold smoke in normal conditions. A standard adhesive foam draught strip does not substitute for a specified fire-door seal.

Likewise, adding an intumescent strip to a non-fire-rated leaf does not make the door certified. Where the opening must provide a stated fire or smoke rating, use only products and details supported by the leaf and frame documentation. Our intumescent and door seals collection is a starting point for viewing items, but final selection must follow the tested door assembly and competent advice.

Preventing condensation around doors

Cold spots and draughts may contribute to uncomfortable conditions around doors, but condensation can also be caused by excess indoor humidity, insufficient ventilation or a cold surrounding wall. Sealing an air leak may improve comfort; it does not solve every source of damp. Inspect for mould or staining near the threshold, especially where rainwater may be getting past exterior seals.

Ventilation and thermal performance need to be considered together. Avoid blocking trickle ventilators or purpose-designed background ventilation. If the door is next to a poorly insulated wall, you may need to improve the broader construction rather than relying on a thicker weather strip. Persistent damp should be investigated and remedied appropriately before applying decorative trim that could hide moisture damage.

Letterplates, keyholes and glazed panels

Sometimes the largest draught occurs through hardware openings rather than the main door perimeter. Letterplates and keyholes can admit air if their seals or covers are worn. Glazed panels may also develop leakage around defective beads or seals, particularly in older exterior doors. Identify the exact source before buying accessories.

When replacing hardware, maintain security and accessibility as well as draught resistance. A new letterplate may need to match existing hole dimensions; modifying the door can affect a warranty or tested security performance. Glazed units should be inspected by an appropriate specialist if seals have failed or the glass unit is misted. Never assume every decorative accessory fits every door construction.

Do self-adhesive foam seals work?

Foam strips are inexpensive and can help with minor, uniform gaps on suitable non-certified doors. Their main limitations are compression life, weather exposure and the risk of using an incorrect thickness. They may peel away if the frame is dirty, damp or poorly painted. Overly thick foam can prevent the latch from engaging properly.

For a busy exterior door, a proper replacement of the manufacturer's original seal profile is often preferable to layering adhesive tape. Test whether the door closes and locks without excessive force after fitting. Keep children and pets clear during adjustment work and stop if locking becomes unreliable. On a fire-rated or security-tested door, only use the system's approved components.

An ordering checklist for door seals

Write down the door material, whether it opens inwards or outwards, the frame profile, the seal gap, and whether an existing groove or carrier is present. Include the dimensions of the threshold and any fitted weather bar. For exterior doors, note exposure to wind and rain and check the replacement part's compatibility with the doorset.

If purchasing a larger quantity for a refurbishment, start with one opening and verify the seal works before fitting every door. Take a photo before removing the original, especially around corners. Buy a suitable length with allowance for cutting and joint details where permitted. Avoid guessing based solely on nominal frame dimensions, since the perimeter of the actual opening is what matters.

When replacement is better than a repair

A new seal cannot compensate for a rotten timber frame, severely warped door, failed sealed-glass unit or locking mechanism that no longer aligns. Replacing an entire doorset may be more sensible if repairs would leave several underlying problems. The decision should weigh cost, safety, security, energy performance and the expected life of the repaired assembly.

Compare the repair cost with the full cost of a suitable new exterior door and installation rather than the product price alone. If you replace the door, verify dimensions, glazing, thermal details, handing and hardware. Consider the external doors buying guide before selecting a new entrance. Keep evidence of the chosen product specification and any installation certificates where relevant.

Fitting and long-term maintenance

Clean and dry the frame before fitting non-certified adhesive products, then follow the supplier's instructions about temperature, surfaces and curing. For groove-fit seals, avoid stretching the material because it can shrink back from corners. Check every edge of the door after installation for a smooth latch action and consistent closing pressure.

Inspect seals seasonally, particularly after winter storms and heavy summer use. Look for flattening, torn corners, detached sections and debris in the threshold. Clean drainage openings where the manufacturer permits, but never seal them shut. Keeping hinges and locks correctly adjusted can extend seal life. If a door is difficult to close or no longer locks securely, seek advice promptly instead of continuing to force it.

Door draught proofing FAQs

What is the best draught excluder for a front door?

It depends on the door and frame system. A compatible replacement perimeter seal and appropriate threshold detail usually work better than choosing an arbitrary thick foam strip.

Can I seal the bottom of any internal door?

Not always. Some doors need undercuts for ventilation and some have certified fire or acoustic requirements. Check the room and door specification first.

Why does my door still draught after changing the seal?

Air may be entering through the frame-to-wall joint, threshold, letterplate or a misaligned locking edge. Identify the actual leak before adding more material.

Are fire-door smoke seals the same as draught strips?

No. Fire- and smoke-rated components must be chosen as part of the certified system. Ordinary adhesive draught strips cannot be treated as substitutes.

Can a door draught cause condensation?

Cold air and low surface temperatures can contribute, but condensation also depends on indoor humidity and ventilation. Investigate all likely causes.

Do draught strips improve sound insulation?

They can reduce leakage through perimeter gaps, but that does not make an ordinary door an acoustic-rated assembly.

Should I replace the hinges before fitting a seal?

If the leaf has dropped or no longer meets the frame evenly, alignment or hinge repairs may be needed first. Check the manufacturer's advice.

Is it safe to add an extra seal to a multipoint-locking door?

Only if it remains compatible and does not stop full lock engagement. Use the door manufacturer's recommended components where possible.

Further buying advice

For wider product choices read our external door buying guide, fire door guidance and door furniture buying guide.

Use compatible parts and follow manufacturer instructions. Do not alter certified fire or security doors without appropriate professional guidance.