As mentioned in a previous post about air infiltration testing with a blower door, draught proofing is probably the most cost effective place to start to improve the performance and comfort of your home. But where to start?
There is a bit of science behind it, the stack and wind effect ,which informs us where to look but essentially it is about plugging the biggest holes first. Common sites are exhaust fans in kitchens and bathrooms which can have a Draft Stoppa (pictured) popped over them. You do need to be careful not to use them without an adequate spacer if using them over the fan/heater combos common in bathrooms and the wiring needs to be changed so the fan operates if the heater lamps are turned on. Similarly, a draft stoppa can be used over the rangehood exhaust from the kitchen. Plumbing penetrations through the building envelope tend to be the largest- check around the pipe penetrations at the toilet, laundry, kitchen etc.
The sum of all the leaks around doors and windows can also add up to a big area so using a draught sealing strip of some sort is very beneficial. We use a timber strip with a compression seal applied to the door frame. It looks good, is long lasting and effective. Door bottom seals come in lots of varieties and are needed too. It is very common to find, even in new homes, that air leaks around the door and window frames at the architrave. It is a sign that the required sealing of the door/ window frame join to the house frame has been inadequate or has broken down. You can apply caulking as needed around the architrave. Fullers Ultraclear is a product that goes on white but dries clear so is well suited to this application. Use gap filler for spots that are out of sight, or colour match as needed.
While the blower door is operating it is easy to feel the air coming in through the electrical sockets and switches. It moves into the wall cavity through the wiring penetrations in the top plate of the wall frame and is then free to move through any hole in the wall sheeting. In general this is a relatively minor source of air leaks but if you are in the roof space doing the other jobs outlined, sealing up those holes around the wiring with caulking or expanding foam is a very inexpensive thing to do.
Other areas to consider are cavity sliding doors, chimneys, fixed wall vents and floor drains all of which can be very significant sources of unwanted draughts. Doing the work with the blower door operating helps inform you how you are going but is certainly not necessary.It is very unlikely you will be able to seal the house so much that you run into problems with ventilation, say under 3- 5 ACH@50Pa but if you do, at least then you will be in control by opening and closing windows as required rather than having air movement when you don’t want or need it.
Our home assessment team can help you diagnose the extent of the problem and pinpoint the sources of air leaks.