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Housing - Renovation: How tight/ leaky should a new sash window be?

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    A colleague has newly-installed uPVC sliding sash windows. They live in an exposed position - weather conditions are in the ‘severe’ category – west facing and subject to much driving rain. However they were not expecting the wind to whistle though the sashes! The installer has been back but the wind still comes in.

    I worked on a job a while back with high-spec timber 3G sash windows and yes, there was some leakage during the a/t test, and casements would have performed better, but the 'wind' did not whistle through in a/t test conditions.

    I should have thought that a brand-new uPVC sash window should perform quite well. What would 'the panel's' expectations be?

    Thanks,

    Nick
    •  
      CommentAuthornigel
    • CommentTimeOct 9th 2019
     
    Not fit for purpose if they don’t keep the wind out when they are new.

    As the seals age most sashes leak though.
    • CommentAuthortony
    • CommentTimeOct 9th 2019
     
    I once had that very early in my life, I refused to pay for them. The lost and I replaced the windows with others.

    They are not suited to exposed locations. The draught strips ate likely brush type.

    The frames have to be installed absolutely straight and square and parallel with in 0.3 mm
    •  
      CommentAuthordjh
    • CommentTimeOct 10th 2019
     
    Posted By: Nick Parsonsthe 'wind' did not whistle through in a/t test conditions.

    IIRC the normal test pressure of 50 Pa corresponds to a F6, so if it's windier than that, or locally-concentrated wind, then that would be expected. Some places/regimes use 75 Pa test pressures I think.
  5.  
    Nigel, you echo my initial thought, but djh has a valid point. I guess it's going to come down to a judgement re how often, and in what wind conditions, the wind comes in. It must be very disappointing with a brand-new set of windows. I don't know what prior advice manufacturers/fitters would give in such (potential) circumstances.
    • CommentAuthorMike1
    • CommentTimeOct 10th 2019 edited
     
    Sliding sash windows are certainly difficult to seal, though I'm surprised that they are that bad as new.

    Worth knowing that there are some alternative sliding sash technologies available - at least elsewhere Europe - where the sashes don't actually slide over one another. For example:

    Adrik (Germany) https://translate.google.co.uk/translate?hl=en&sl=de&u=https://www.adrik.de/fenster/WIN-Hochschiebefenster/Holz-TypS.html

    and Solberg (Denmark) https://www.solborg.site/enl - who also have a UK installer (Enlightened Window) https://enlightenedwindows.co.uk/products/german-wooden-windows/s-series-sliding-sash-window/
    •  
      CommentAuthornigel
    • CommentTimeOct 10th 2019
     
    I have the Solberg ones fitted in my house and they have a clamping system so seals are compressed when closed.
    It also means the seals don't wear out.

    They are on an exposed elevation and they don't leak and they are timber.
    •  
      CommentAuthornigel
    • CommentTimeOct 10th 2019 edited
     
    Posted By: Nick ParsonsNigel, you echo my initial thought, but djh has a valid point. I guess it's going to come down to a judgement re how often, and in what wind conditions, the wind comes in. It must be very disappointing with a brand-new set of windows. I don't know what prior advice manufacturers/fitters would give in such (potential) circumstances.


    That would depend on whether they were told it was an exposed location.
    If they were I would expect them to caveat that above a certain wind load they may leak.
    If they said nothing I think it would be reasonable to expect them to be fit for purpose.
    •  
      CommentAuthordjh
    • CommentTimeOct 10th 2019
     
    The Solberg ones say: "Airtightness to class 4 standards at 600 Pa". That's a good spec to look for.

    Posted By: nigelThat would depend on whether they were told it was an exposed location.

    Even if they weren't they ought to be able to make a rough assessment given the address assuming they knew that. And especially if they visited site to measure up etc. I suppose it's all going to depend on the details of the manufacturer and installer. What expertise and knowledge they hold themselves out as having or might reasonably be expected to have, what the contract says, etc. It seems like a specialist solicitor or maybe an advice service like Which or somebody might be useful. Perhaps any professional institution they belong to, although that might be part of the problem rather than the solution.
  10.  
    Posted By: Nick Parsons
    Nigel, you echo my initial thought, but djh has a valid point. I guess it's going to come down to a judgement re how often, and in what wind conditions, the wind comes in. It must be very disappointing with a brand-new set of windows. I don't know what prior advice manufacturers/fitters would give in such (potential) circumstances.


    Nigel replied:
    "That would depend on whether they were told it was an exposed location.
    If they were I would expect them to caveat that above a certain wind load they may leak.
    If they said nothing I think it would be reasonable to expect them to be fit for purpose. "

    Nigel and djh:

    I gather it was supply and fit. Although I suppose it is possible that it was not windy during the survey and installation, I agree that one might expect local knowledge to give them an idea of the exposure.

    Thanks for all your thoughts.

    Nick
  11.  
    Sliding and sash windows cannot be made airtight, no matter what. Avoid at all costs.

    Paul in Montreal.
    • CommentAuthorowlman
    • CommentTimeOct 11th 2019 edited
     
    .
    • CommentAuthorowlman
    • CommentTimeOct 11th 2019
     
    Posted By: Paul in MontrealSliding and sash windows cannot be made airtight, no matter what. Avoid at all costs.

    Paul in Montreal.



    +1
    •  
      CommentAuthordjh
    • CommentTimeOct 11th 2019
     
    Posted By: owlman
    Posted By: Paul in MontrealSliding and sash windows cannot be made airtight, no matter what. Avoid at all costs.
    Paul in Montreal.

    +1

    I'd tend to agree although the Solberg spec does claim reasonable performance. And FWIW my lift-and-slide patio door has good performance so I suppose something similar could be done for sash windows.
  15.  
    Apparently they are available with "class 4 air permeability". That is the best class but I don't know if its objectively good. This one caught me eye because they also use evacuated glazing:

    https://www.gowercroft.co.uk/timber-windows-and-doors/the-winston-heritage-sliding-sash-window/

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