The windows have arrived on site and been installed. This is an enormous step forward as it now means we are watertight, the build is drying out, and we can start first fix.

These are Internorm triple-glazed units, which have a timber substructure internally and an aluminium exterior. They also have a thermally broken frame. This allows a layer of thermal insulation within the frame, preventing heat-loss, giving an incredibly high level of thermal performance (a U value of 0.7W/m²).

The crucial thing with windows is not only the quality of the units, but the installation. There are quite a few stages to ensure the window is fitted for maximum performance. One way we are doing this is by using an expanding tape. There are a number of products on the market, but what they all do is stick to the window reveal and start to expand. They expand out to fill all the air gaps between the frame and the building, helping create an airtight and watertight seal. They’re much better than mastic, which can harden and crack over time.

We’ve then used another tape to seal the join between the pane of glass and the tape on the reveal. This, in turn, will get covered by a breathable membrane to help windproof the system externally.

  • Owen Short

    Interesting, but what a faff building has become! End up living in a plastic bag with forced ventilation. Would be better if we had cheap renewable energy. However, Charlie, surely your last para has an error – you can’t have sealed the pane of glass to the reveal, you must mean the window frame. Happy building. O.

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