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  • #1526

    I’ve just uploaded a set of documents related to indoor environmental quality (IEQ) to the Best Practice Library (BPL). Around 14 so far. They are in the “Indoor Environmental Quality” folder.

    They include reports, info sheets, articles and links covering moisture, ventilation and different aspects of indoor environmental quality, and come from a range of authoritative sources.

    I’ve collated these docs as we are starting work on developing an Advisor Guide to help advisors ask the right questions and make good recommendations to clients when faced with internal moisture problems.

    Please check out what is there. If you know of other good resources that aren’t there please either upload them yourself or let me know. Please feel free to add comments (at the bottom of the page when you’ve downloaded the doc from the BPL too)

    Thanks

    Sally

    #1527
    philgregg
    Participant

    Thank you Sally, I have started reviewing the documentation you have added. I am sure it will be helpful in identifying the correct remedy for the different situations, as I am now starting to understand one solution doesn’t fit all ( darn)I have to admit there is a lot to absorb. It would be helpful if one day a basic chart was designed for us laymen in the field,The chart would identify different scenarios and what may be the different issues to start eliminating to get the right solution.

    The issue that has created me the greatest concern in recent times is 1970’s brick  or wooden homes, metal roofs, no building paper underneath the metal, re insulated correctly under the govt scheme. In a few cases  I have seen recently the mould on the outside walls and ceiling has been horrendous. I have been at a loss to explain this.

     

    #1528

    Phil, there is a good explanation for this I think, but I am not the person to attempt to explain it to you.

    Gleb, I assume this is a symptom of the issue you have been describing lately? Can you offer Phil any more insights?

    Or anyone else?

    Thanks.

     

    #1529

    Oh, and Phil I meant to say. The purpose of the work I am doing is precisely to try to synthesis all the heft reports into something useful that advisors can use to help diagnose moisture issues and make good recommendations to clients to suit their personal circumstances.

    Thanks for your feedback. It would be good to hear similar stories from others. Very useful.

    Sally

    #1541
    Ian McChesney
    Participant

    Re Phil’s query. I’m not sure that the mould issues are tied to a single cause. The ceiling re-insulation will have reduced heat loss into the roof cavity and lowered the temperature of the cavity on cold nights. This may be causing greater condensation on the inner surface of an unlined metal roof. It may be dripping and wetting insulation in certain areas, and getting through to the ceiling gib….but, it seems a bit unlikely I think. For mould on an insulated ceiling I would most likely suspect lack of internal ventilation, particularly if they are 70s houses with aluminium window frames.
    On external walls I have observed mould/moss growth on external 60s/70s walls on a few houses – they seemed to share the common characteristics of being shady walls and summerhill stone/ concrete block. This makes me suspect water absorption – maybe through breakdown of some of the mortar and into the surface pores of ageing concrete, and just creating a bit of a breeding ground.

    #1542
    Vicki Cowan
    Keymaster

    I’d be interested if Gleb could comment also – the roof space problem Sally referred to is something we talked about in our conference call the other day.  It’s something I’ve heard about occurring in a number of situations – as Ian says as a result of the temperature of the cavity being lowered on cold nights causing condensation on the metal which then wets the insulation and this wicks through to the ceiling gib.  Sadly not unlikely, it does happen.

    Another more common cause can also be damp subfloors -particularly with brick veneer where often the cavity was left open between the subfloor and the roof space – the water wicks all the way up to the roof space – and you see mould growing on the ceiling and top of the external walls – but its actually caused by a damp underfloor.

    This can happen in other types of cladding situations also, where holes were drilled in the bottom and top plates at the time of construction to help green timber dry, or you can just get a stack effect where ground moisture can be drawn up through open paths in the wall cavity into the ceiling space.

    So the ceiling can look OK – but the problem is actually one of rising damp from the subfloor.  Given about half of our subfloors are underventilated (BRANZ House Condition Survey), and that even a dry subfloor produces 45 litres of moisture a day (BRANZ data) – and more than 180 litres/day if there’s ponded water under the house, subfloors can often cause quite major ceiling and wall mould problems.  The trick is to look down not up for the cause!

     

    #1553

    Hello Phil

    If you look at the house itself, its surroundings and how the occupants live in the house you may identify a number of contributing factors.
    In my opinion it is better to start by eliminating as many potential causes as possible (provided they do not involve major work or cost) rather than to try to determine exactly which one is contributing the most to the problem. Maybe an example will help. I went to see a house with mould problems even on some internal walls!!! 20+ possible causes or contributing factors became evident immediately:

    – the worst problems were in the bedroom (1 – people spend many hours in bedrooms releasing moisture) located in in the South (2 – so no solar heat gains) corner of the house (3 a corner, therefore bigger heat losses) where two people slept (4 – more people, more moisture) and which remained unheated (5) and had no insulation in ceiling (flat roof), under the floor or in the walls (6). The house had been broken into before so windows remained closed most of the time (7). The house was built in the 1940’s and the walls were finished with plaster (8), which tends not to provide goood wall moisture management and possibly not good ventilation of the wall (19) and flat roof (20) which has less ventilation and more chances of leaks than one with trusses. The plaster had a few very thin cracks in which mould was growing outside (9 – a sign that moisture is getting in or accumulating in the cracks). The grass was very green around the base of the downpipe in that corner, so water from the downpipe may have just been seeping into the ground, which is not uncommon in older houses (10). The ground along one of those walls fell towards the house rather than away from it (11). There was no polythene laid on the ground under the house and ventilation to the subfloor was rather limited as it often is in houses on a concrete ring foundation (12). Palmerston North is built on swamps and lagoons and the water table is high so many areas in town have damp ground (13). This house was not very far from the river (14). Extract fans were ineffective or missing (15). Weeds could be seen growing in a couple of places inside the gutters (16). The joint between windows and plaster could have also allowed water in places, so that would have been something else to check (17). The house was a flatting situation, in which in my experience people tend to leave their bedroom doors closed so ventilation is poor (18).

    Instead of trying to figure out if the downpipe is contributing more to the problem than the gutter or the cracks in the walls or the lack of ventilation, I think that it is better to address as many of those possible causes as possible, given that if they turn out not to be causing problems now (maybe moisture is not getting all the way through the cracks in the plaster yet or the gutters are not backflowing into the roof and wall yet) they may well become a problem in the near future.

    Some of the solutions may be cheap or zero cost but others will require that the owner of the house considers his/her options very well. A good example in this case would be the roof. Maybe spending a bit more and replacing the flat roof with a pitched isulated roof is the best option, as it would address more than one problem and it would help to prevent leaks.

    Sorry for the length of the reply. I hope it helps.

    #1573

    This is a fantastic response Adriana, thanks.

    From my perspective this is exactly the approach we would like to see people take and its an approach I will be trying to reflect in the resources we are developing.

    Cheers,

    Sally

    #1584

    And here are some of Gleb’s pics, showing damage in the ceiling due to condensation which has come about since the ceiling space has been insulated.

    We now have the ability to upload files to the Forum!

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    #1589
    philgregg
    Participant

    I have reviewed ( in my head not revisited ) some of houses that have shown an increase in mould issues since being reinsulated. These are some of the common factors

    1. 1950’s – 1960’s build, 2 is on a concrete pads, 2 are one wooden floors with garage under house.

    2. All brick.

    3. Low metal roof 14 degree pitch, no building paper

    4. All have been re insulated with blanket polyester, when there is an underfloor a moisture barrier was applied with polyester insulation under floor.

    5. Heating is being used in homes, some fires some heat pumps

    6. Manual ventilation is being used in some cases

    7. Mould is occurring on edges of ceiling at outside wall as well as on internal outside walls. Doesn’t necessarily need to be southern walls.

    It make you wonder if  there may be a housing era that doesn’t react well to ceiling insulation as a first response as it creates a problem/s elsewhere. One could be lead to believe that the walls and ceiling need doing at the same time or some other interaction needs attending to first.

     

     

     

    #1590
    Ian McChesney
    Participant

    The house characteristics Phil describes, (and Gleb’s photos), has me thinking about the effect of the thick ceiling insulation in these kinds of low roof-pitch houses. I wonder whether the insulation installed right out to the edge of the roof is actually cutting off what might have been some natural ventilation flows into/out of the roof cavity. For instance, air flow from the wall cavities is now largely cut off (from vent holes in the bricks for those with concrete floor, and from the underfloor space for suspended floor (and Phil says the floors are covered so the air should be dry)), as is air flow from any ventilation holes in the soffit (some houses have them), and from the gaps between the bottom of the corrugated iron and the outer roof purlin. If the insulation substantially reduces air flow from below and from the side, and tightly fitting long-run iron from above is also reasonably airtight (compared with older roofs and tiles), have we created a fairly airtight little high-humidity roof cavity space in which moisture is largely retained and goes through cycles of condensation-evaporation during night and day? And any extract fan venting moisture into the roof space would exacerbate the problem. I don’t know….any other thoughts?

    #1591
    Vicki Cowan
    Keymaster

    I think this is an issue that Housing New Zealand have also struck – I have had a conversation with one of their asset managers about roof cavity ventilation and the need for this.
    I’m going to do a bit more investigation in this area – I think this is something I’ve seen some research reports on from overseas authors.  Hopefully might dig up something over the holidays which sheds some light.

     

    #1592
    Norman Smith
    Participant

    Picking up on Adriana’s bullet point – “The house had been broken into before so windows remained closed most of the time”.

    Some years ago I carried out work for Housing NZ with the objective of reducing mould in bedrooms in many of their properties in a less than salubrious part of Lower Hutt. They were a little suprised at my No 1 recommendation –  fit security stays to give tenants the confidence to leave windows open at night.

    It worked at many levels – less moisture, easier to heat, healthier and happier tenants, no need for HNZ to have to keep repainting. It remains the single most effective and cost effective intervention I have ever been involved with.

    Question for the day – how much water vapour is created per night by an adult when they are sleeping? Go on, have a guess, then multiply it by 365.

    Cheers, Norman

     

    #1593
    Jo Wills
    Participant

    I’ve also had conversation with Housing NZ about opening windows…lots of people living in low income areas (some dangerous low income areas) opt for the security of closed windows (and are advised to do so). I am sure there are multiple products on the market but the person I was speaking to suggested all that’s needed do remove a window security latch from the outside is a screw driver.

    #1615

    I’ve just uploaded a BRANZ report that looks at moisture in houses and finds that the cause is sub-floor moisture finding its way to the roof space. The report is from 1988 but still very pertinent. Its in the Internal Environmental Quality folder in the Best Practice Library. (Moisture Damage in Roof Spaces).

    Thanks Ian McChesney for sending it to me.

    Sally

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