Quick answer
What homeowners need to know
Draught-proofing targets unintended leakage around doors, windows, floors and penetrations while preserving required ventilation and combustion safety.
Use inspection or testing to find leakage paths before replacing unrelated components.
Key takeaways
- Find the leaks before buying seals.
- Old fireplaces and unused vents are common culprits.
- Draught-proofing and ventilation must be planned together.
- Insulation, glazing, airtightness, ventilation, moisture and heating work as a connected system.
Comfort, moisture & efficiency
Where to focus a draught-proofing renovation
Find the leaks before buying seals. On a cool, windy day, move slowly around doors, windows, skirting boards, power points and floor penetrations, feeling for moving air. Some assessors use blower-door testing to pressurise the house and locate leaks more precisely. Mark each leak on a floor plan so the scope addresses it, rather than replacing parts that were already performing well.
Old fireplaces and unused vents are common culprits. An open chimney without a damper can draw warm air out of a room constantly. Discuss options such as a chimney balloon, a sealed flue or removing the chimney with your builder, but first confirm the fireplace will never be used, because blocking an active flue is a serious safety risk. Unused wall vents should be assessed, not simply covered.
Draught-proofing and ventilation must be planned together. Reducing uncontrolled leakage makes a home warmer and easier to heat, but moisture from cooking, showers and breathing still needs a way out. Before sealing a house more tightly, check that bathrooms and kitchens have working extraction that vents outdoors. Rooms with open-flued gas or solid fuel appliances need specialist advice before air paths are reduced.
Scope before solutions
Decisions to make before committing
Settle these points before an idea becomes an order, contract or construction instruction.
Use inspection or testing to find leakage paths before replacing unrelated components.
existing envelope and moisture condition
access to walls, ceilings and subfloor areas
interaction between insulation, glazing, ventilation and heating
Practical sequence
A step-by-step planning process
- 01
Define the exact outcome you need and how success will be checked.
- 02
Assess moisture sources, insulation continuity, draughts, glazing, ventilation and heating together.
- 03
Prioritise repairs and passive improvements before sizing new mechanical systems.
- 04
Model or compare options using whole-of-life comfort, energy and maintenance outcomes.
- 05
Commission controls and give occupants clear operating and maintenance information.
Cost and time
How to build a more reliable budget and programme
A fixed price or completion date needs a measured scope and a site visit. Use suitably qualified professionals for energy modelling, electrical work, moisture diagnosis and any alteration that requires consent or specialist design.
Use the calculator, then request a site-specific assessment.
Risk control
Common mistakes to avoid
- Sealing indiscriminately without ventilation planning can worsen moisture or indoor-air problems.
- adding insulation without managing moisture and ventilation
- selecting products independently of the whole-house performance strategy
Accuracy and compliance
Use current official information
Primary sources used for this guide
- Insulate your home to improve energy efficiencyEECA
- Design or renovate a home for energy efficiencyEECA
- Check if you need consentsBuilding Performance (MBIE)
Common questions
Frequently asked questions
How do I find draughts in an older house?
Start with a slow walk around the house on a windy day, feeling for air movement at doors, windows, skirting boards, floorboards and service penetrations. A lit incense stick, used carefully, can reveal subtle airflow. For a more thorough picture, some energy assessors offer blower-door testing that pressurises the house and shows leakage points.
Can draught-proofing make a house damp?
It can if ventilation is not planned at the same time. Sealing gaps reduces the accidental airflow that was carrying some moisture away. Without effective kitchen and bathroom extraction and a controlled way for fresh air to enter, humidity can rise and condensation may increase. Check extraction first, then seal the leaks you have identified.
Is it worth draught-proofing the floorboards in a villa?
Gaps between old floorboards can let cold subfloor air into living spaces, so addressing them often improves comfort. Options include filling gaps, adding underfloor insulation with an air barrier, or laying new flooring over the top. Check the subfloor for moisture first, and keep subfloor vents clear so the space under the house can still dry out.