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How were cavities closed in the 1980's? Is it possible/worthwhile to redo?

  • 14-10-2022 8:31pm
    Registered Users Posts: 923 ✭✭✭

    I'm looking to replace a garage door with something along the lines of a uPVC patio door in a 1980's house.

    The walls are 300mm, with a 100mm cavity. I intend to have them blown but haven't yet. I'm wondering how cavities were closed around doors and windows at this time?

    I'm guessing there's much better ways to close around windows now, avoiding cold bridging and so on. Is it possible to refit these solutions when replacing doors and windows?


  • Registered Users Posts: 5,209 ✭✭✭10-10-20

    I think, and I could be wrong, that they often used a "return" block from the inner leaf. This means that at the door reveal every second block is rotated 90 degrees to semi-close the cavity, and half blocks are installed in the teeth to close it fully. A bit like these images:

    Only investigation of the reveal will reveal the truth!

    Hopefully they put a piece of DPM between the interface between the inner and outer reveal, otherwise it's not just a thermal bridge, but also moisture bridge too. The guidance would probably be to retro-fit a DPM if possible, otherwise an insulated cavity closer (unlikely).

  • Moderators, Regional North West Moderators Posts: 44,832 Mod ✭✭✭✭muffler

    Pretty much as stated above. A lot would have had the cavities closed off with a bit of Aeroboard and plastered over. As mentioned the opes would need investigated to determine what's there and what's needed.

  • Registered Users Posts: 923 ✭✭✭MegamanBoo

    Thanks folks 👍

    Who'd be best to take on this work? Am I looking for a good small builder or blocklayer?

    I'm guessing the fit service window providers offer would just be to throw them in as is?

  • Moderators, Regional North West Moderators Posts: 44,832 Mod ✭✭✭✭muffler

    You will need to make sure the dpc's are fitted properly and if the cavities aren't closed then fit proprietary closers. The window fitters won't do this so you will need to get a good blocklayer or small time contractor. The only problem is these works will need to be done before the window fitters appear which means removing the windows.