Living in a pre-1950s house offers a sense of charm, but compared to a modern home there’s a vast difference in how much air they will leak. There are three main reasons, the design, the types of building materials used and the decay that occurs over time.
Homes from this period were often constructed with materials such as corrugated iron on the roof, wooden frames, weatherboards, horsehair plaster and single pane windows. It was high maintenance just keeping it looking good on the outside let alone the internal structure. Open fires were a popular source of heating, however chimneys are a major source of air leakage. Fixed open vents in the toilet and laundry also make creating a home airtight impossible.
Older homes are often extended and renovated. Depending on how skilfully these works were carried out by the builders, there could be many places where draft could form. For instance, did the builders install insulation and sisalation effectively and properly weatherproof the additions?
Another important consideration for pre-1950s homes is ground movement. If the ground has shifted even a little, it could cause cracks in everything from the foundations to the walls and ceilings.