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    Sarah Grant

    Hello all,

    I’m a rookie HPA (just completed part 2 of the training), and have been asked the following question from a Trustee of the Board I work for.

    Dear Sarah,

    Our guest room is a later addition onto the house.
    For two reasons it is the most cold room and with black fungi
    developing at the back of the curtains.

    I get someone in next week to look at better thermal curtain options.
    I also wondered whether double glazing would be affordable, good solution.
    I sadly assume Nz is not ready yet to subsidise on large scale single
    for dpuble glazing in all existing houses. Is this right?

    Do you have a few pointers in right direction re whom to contact, a website.
    Particularly as it will affect price I wanna pay for curtains if we
    also double glaze that room only.


    My reponse was:
    There are a few things to consider before you start going ahead with remedies – they are:
    *how is the room used? you mention it’s a guest room so I would assume it’s used intermittently with the door closed to the rest of the house when not in use?
    *where is the moisture coming from? moisture will condense on the glass in the coldest room it can get to by preference, but there may be a source of moisture in the house that’s causing the damp air to begin with. Do you have a good extractor fan in your bathroom which is vented to the outside, and is it used when showering and ? Do you have a range hood in your kitchen and is it always used when cooking?
    *is there insulation in that part of the roof? what about underfloor and the walls?

    Having good curtains is important (make sure they’re two layers, not just ‘thermal backed’ as that really doesn’t do anything) for retaining heat in the house, but be aware this won’t help your moisture problem (particularly if window condensation is causing the curtain mould – which seems likely). In fact, good curtains can increase condensation on the window as the glass gets even colder than with less good curtains.

    Double glazing isn’t currently subsidised and to my knowledge there are no plans to do so. It is a reasonably expensive (although beneficial) step to take – I would recommend trying to minimise the moisture in the house and removing it through good ventilation practices first and then assessing double glazing as a more capital intensive retrofit in the future. I’ve attached a powerpoint presentation I’ve put together today to aid you with understanding moisture problems and solutions in a home. (This needs pictures and things before it goes out to the public – but the content is sound.)

    I’m not yet familiar with providers for double-glazing, so I can’t help you there yet sorry. I have some work to do on this as time allows.

    It would be great to have some feedback on the Trustee’s situation and also my response and the content in the draft powerpoint, which still needs pictures and diagrams added etc (attached as a PDF). Please be gentle and remember I am a rookie at this! Thanks in advance for your help.

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    Vicki Cowan

    Hi Sarah
    that sounds like an excellent response, you’ve covered the issues and common causes of moisture well.
    If the house has a suspended floor, probably also worth getting him to look at the soil under the house – if it’s damp, or there is a solid block perimeter, then chances are the underfloor is contributing a fair bit of moisture into the house – even apparently dry underfloors can hoover up the moisture.

    Just on the double glazing, there is a cheap option that people can look at – DIY plastic shrink wrap double glazing. It costs about $30 for a kit (you can buy them online from CEA) which will do several rooms worth of windows. Research has shown they perform pretty well, and they can make a big difference in hard to insulate rooms – and generally reduce the amount of moisture condensing on the windows as well. And while some people take them down every year, I’ve had some up in my kids bedrooms for 6 years, still going strong.

    Jo Wills

    WOW Sarah, just to reiterate Lois’ comment, what an excellent response! The DIY kits can be bought online from CEA http://www.cea.co.nz/shop/diy-insulation-draught-stoppin?orderby=manufacturer or Sustainability Trust http://sustaintrust.org.nz/shop

    Really good to know how long you have had your ‘double glazing’ up for 6 years Lois, that’s good to be able to tell other people.


    Hi Sarah

    I second Lois and Jo’s comments. Well done!

    The only thing I might add is to be explicit about regular ventilation of the room. We have a cold spare bedroom and I make sure I open the windows whenever I can to let some air in/out.

    Also, it would be good to remind them not to dry clothes indoors on a rack and to check whether they are using an unflued gas heater. You may have already covered these points off.

    On this topic, we (the Hub) are working on an advisors’ guide on internal moisture (its slow progress as its currently unfunded) that would supplement the HPA training and should provide more guidance in this area. Your question is useful to help us shape that.

    Out of interest. Would you (or anyone else reading this) be interested if we could arrange a “masterclass” or workshop on Internal Moisture specifically. There would be a cost attached but we would try to keep it minimal and also try to arrange it alongside another event so that travel can be minimised. Just putting it out there. It would be useful to get a sense of interest in something like this.

    Also, Sarah, can you please clarify your question about the “Trustees”? Who were you referring to there?

    Thanks, and well done.



    Just re-read the question about the Trustees. Ignore my question… : )

    Sarah Grant

    Thank you ladies for your support and helpful comments – further information has come through from the enquiring Trustee (of Sustaining Hawke’s Bay Trust):

    Thanks heaps for the questions and PPT re my inquiry.
    I have not been able to open your PPT on this ipad but will do so
    tomorrow from my Mac.

    We do have range hood in kitchen (hate noise so lots of times just
    windows open while cooking), extractor fans in bathrooms and duct vent
    system in ceiling pumping dry/warm air in etc etc.
    The challenge with this room is that it is a later add-on put on slab
    of concrete and no insulation in ceiling with flat color steel roof.
    Rest house is now very well insulated but this room ltd opp.
    Also, due to lay out, less airflow from warmer hall way to this room.

    So, i am quite keen on double glazing and do some initial research.
    We now will regularly have woofers staying with us and they will want
    a warm room.

    If you hear/see anything, please let me know.

    Me again: For some reason I knew (or assumed correctly) that the extension was on a concrete slab, hence no enquiring about conditions for rising damp. I’ve been working on a separate Ventilation powerpoint which I aim to send through to the Trustee as well as soon as I’m happy with it, which should address some of these points.

    Thanks for the reminder about the film double glazing, we are going to get some as a demonstration in the Environment Centre for our window / curtain display corner so I’ll invite the Trustee to come and have a look before she makes her final decision. I understood that the film isn’t that viable on aluminium windows as the frame is too shallow to provide much of an air gap – is this correct?

    I would love to participate in a masterclass – but wonder if it can be accessed remotely via skype or another live videostreaming medium? This would further reduce the cost by eliminating travel and accommodation, and also would potentially make it much easier to attend time-wise. There are systems available where the viewers can participate either by forum style communication during the video or through direct feedback verbally. Could be worth looking into anyway. 🙂

    Sally, the reference to Trustee was in relation to the source of the enquiry – we haven’t publicly announced the new HPA capabilities (mainly because I haven’t passed yet!) so only people directly connected with the Environment Centre are asking me questions at this stage – a good way of ‘pilot testing’my knowledge and advice before subjecting the public to my newness!

    Kind Regards,

    Paul Hansen

    A few further thoughts. Scratch around the edge of the concrete slab this extension sits on if it was laid separate the house pad. It should have a quality (250 micron) plastic moisture barrier between the ground and the concrete pad. This would restrict moisture wicking back in through the concrete. Personally for me I would be interested in pulling the flat roof off this extension and putting in the insulation Limited space in this void may inhibit product at all or minimise the R-Value of what does go in, but there are products that could be used, ie high density under floor if only 80mm space worse case scenario (you need a 25mm breather gap between insulation and the roof element). This is not a big job but you would want to be confident of the skills of those re-applying the roof (ie use bigger gauge shank on roof screws to guarantee the hold). I would only use polyester insulation for this job as there is no way of accessing this product in the future to check and/or upgrade.


    Hi Sarah,

    great response 😉

    You have covered all the important first steps to deal with the problem.
    The next question would be, are they only concerned about the mould they noticed on the curtains or is it a bigger problem? There is the possibility that mould could be in other areas as well (corners, within cupboards or on the back of skirting and plaster boards)!
    As you know I’m a big fan of measuring temperature and relative humidity to get a better understanding what they are dealing with and to tailor the next steps to their requirements.
    In the meantime they should measure the relative humidity in the room and change their ventilation and heating regime to get the relative humidity below 70%.
    In case there is no insulation in the ceiling it is very unlikely have any insulation in the walls. For that reason double glazing should be further down the list.
    I would agree with Paul to insulate the ceiling first.
    Cheers Carsten

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