Draught-stopping and airtightness

Even well insulated homes can be hard to heat if draughts constantly replace hot air with cold air. Good building airtightness and controllable ventilation provisions let you manage air replacement for a warmer, healthier, more comfortable home.

Block up the draughts in your existing house

Blocking up draughts is usually cheap and relatively simple to do. There's a simple trick for finding draughts - on a cold, windy day look for curtain movement and use your damp hand or an incense stick to trace the source of your draughts.

Common sources of draughts and simple solutions

Windows/doors don't fit snugly in frame (they rattle or you can see daylight around the frame). Get tips on window and door repairs from the ConsumerBuild website.

Loose hinges/catches/latch sets on windows/doors. Tighten them so doors and windows are pulled in tight to the frame.

Window/door trims not sealed properly. Seal around trims with clear or paintable sealants. If the windows or trim are being replaced, seal the gap around the window or door frame with an air seal strip and polyurethane foam.

Rubber seals around aluminium joinery damaged. Get your seals replaced as required.

Gaps under exterior doors. Fit draught excluders to the bottom of exterior doors and internal doors to cold areas (garage, laundry etc). For standard exterior doors, the most effective option is usually a spring-loaded, automatic door seals that lifts and lowers automatically when the door is opened and closed. Alternatively, brush strip seals can be used.

Gaps around openable wooden windows and exterior doors. Seal around them with weather stripping - find out more about weather stripping.

Gap around chimney where it goes through the ceiling. Close the gap using a non-combustible sealant.

Unused fireplaces. Block the chimney - a rubbish bag filled with shredded newspapers works well. Make sure it's very obvious so no one tries to light the fire with a blocked chimney.

Ceiling hatch. Make sure it's correctly fitted and use weather stripping to seal it.

Gaps between floorboards. Use a flexible, clear silicon-based or latex sealant to fill the gaps. For holes, cover from underneath with a small square of timber and glue a bung of matching wood into the hole. Cut out the bung with a hole saw making it slightly bigger than the hole for a good friction fit. Fill the central pilot hole with wood filler and sand smooth.

Unsealed skirting boards and cornices. Use flexible silicon-based or latex sealants to seal the top and bottom of skirting boards and cornices, or remove them and foam the gap where the floor and wall or the ceiling and wall meet.

Gaps around electrical wiring and plumbing passages. Seal using silicone sealants (for smaller gaps) or polyurethane foam (for bigger gaps). These passages are often hidden so don't forget to look behind kitchen and bathroom cabinetry and inside wardrobes and hot water cupboards.

Extractor fans and rangehoods. Models with backdraught shutters help prevent draughts - if you have them, check that the backdraught shutter is working properly.

Air leakage through some recessed downlights. Air leakage and heat loss can be a real problem with recessed downlights. Sealing or covering recessed downlights can create a fire hazard, so the best solution is to replace them. Surface mounted or suspended light fittings allow you to plug the holes in the ceiling and can be insulated right over.

Choosing and fitting weather stripping

You can seal up gaps around openable wooden windows and doors with weather stripping - it's cheap to buy and easy to install.

Common DIY weather stripping products available from selected hardware and online stores include:

• Self-adhesive foam draught seals. These are quick and easy to install, but become less effective over time due to permanent set (memory). They are available in varying thicknesses to suit different gap sizes.
• Self-adhesive V-seal. This is made from a plastic strip that is folded into a V-shape and molds itself to the gap. It is very versatile as it fits a wide range of gap thicknesses, is effective for uneven gaps and can be used for both hinged and sliding doors and windows. The Warm Up New Zealand: Heat Smart programme uses V-seal type products.
• Self-adhesive soft rubber seals. These provide durable compression seals and come in varying shapes and sizes to suit different applications and gap sizes.
• Self-adhesive soft woven pile draught seals. These are suitable for sliding door and window applications.

Make sure you choose the right product for the job, and the right thickness. Measure the size of the gap by opening the door or window and seeing how many pages of a notepad, magazine or book you can fit into the gap. Then measure their thickness.

Clean the paint surface before installing self-adhesive seals or the strip won't stick.

Traditional single- or double-hung windows can be difficult to seal. You can seal any that you no longer need to be openable with clear silicon-based or latex sealant.

When building and renovating, consider air tightness

Good air tightness helps you manage your home's warmth and comfort - so if you're building or renovating, take the opportunity to get it right.

>> Find out more about airtightness and designing to keep in the heat.

Blower door test

For a thorough and accurate assessment of air leakage in your home, you can hire a qualified technician to conduct a blower door test. A blower door test, which depressurizes a home, can reveal the location of many leaks.

This test is usually only worth considering if you are building new or undertaking a major retrofit project so that you can actually seal any identified leaks effectively.

>> Find a provider by searching the internet for "Blower door New Zealand".

Good airtightness means better ventilation control

Good airtightness allows you to control your home's ventilation. Ventilation is an important part of a healthy indoor environment, as it helps maintain air quality and remove moisture.

Air leakage (through draughts) creates uncontrolled ventilation which can be problematic. When it is cold, air leakage can make a home hard to heat. If the weather is warm and still, there may not be enough air leakage to remove moisture and maintain air quality. Air infiltration can also allow mouldy and dusty air from the subfloor and attic to enter the house which could cause health problems.

With a relatively airtight home and controllable ventilation you can manage air replacement for a healthier, more comfortable home all year round.

>> Find out more about ventilating your home.