Retro-fitted double glazing?

[flyingcrocodile46]

So far as I can determine, new houses in NZ are built neither cheaply nor quickly.

Tis true. Gone are the days of the old Beazly, Neil, Sunset etc homes that were actually pretty cheap. Peoples wants have turned to needs in the kitchens, ensuites, wardrobes, family rooms, studys, and internal garages of thier homes, resulting in a near doubling of size of the average home. Along with more expensive flooring fixtures and fittings tastes (wardrobe organisers, more lights and power points, granite bench tops, more complex cabinetry & $5000 faucets etc) that seem to have become the norm.... small wonder they cost a lot.

Another factor is the price of land. With 400M2 sections (which are generally not flat and cheap to build on) going for $200-400K it doesn't make sense to put a 100M2 (true low spec) $90K shoe box on it.

[flyingcrocodile46]

As far as the glazing goes. What is cost effective and what isn't depends on the options available to you. Those options and degree of likely success are dictated by the the type of joinery you have to start with. For most it is likely best to replace the windows in their entirety to achieve a worthwhile result.

To my knowledge, none of the varied options discussed so far will achieve better than 100% value for money and many will net a lot less.

If considering one of the currently marketed solutions I would want to see a house done and talk to its owners (after a winter) to best determine likely performance. I would not accept claims made by the suppliers.

[Maki]

The thing to keep in mind is that the reality is that single glazing does not cut it for most New Zealand locations, unless you accept an uncomfortably low inside temperature. Once the temperature starts to slide towards freezing the only way to keep a house with large single glazed windows warm is to use vast amounts of energy to heat it. You could easily be losing around 150W of energy per square metre of single glazed glass.

Our neighbors have a HRT ventilation system and the condensation inside their windows on cold morning is nevertheless massive while we have next to none and no ventilation system. It was interesting to note that sometimes a thin film of condensation forms on the OUTSIDE of our windows. That means the outside is quite cold and it also means the windows insulate very well since the temperature inside our house is usually around 15C on cold nights. We don't have any heaters turned on at night.

[mashman]

couldnt be bothered reading the lot, but if you use anything other than a proper sealed unit you will still get condensation appearing & mold growing ..... A sealed unit doesnt.
Dont use a perspex type plasitic as it breaks down & becomes discoloured & brittle. Polycarbonate is the bizzo if you use a plastic but its hellishly expensive, more so than a new sealed unit.
Wooden frames can have the rebate routed to accept a modern sealed unit. Normally an aluminium framed window can have the existing beading cut down or a new one can be obtained if needed.

+2 What ^ said...

We've built 2 houses since we've been here. The first brick. Condensation all over the place. The second, particle board. Condensation all over the place. What do they have in common, shitty unthermally broken aluminium windows. We used to live in Scotland and very very rarely had condensation. PVC is this shizzle in comparison. We hope to build a third at some point. The next one is going to be as passive as possible and sealed as air tight as possible. The fit of the windows and doors make all of the difference from what we've found. Even those who have thermal broken windows get condensation and from what I've seen it's because of those stupid condensation run off holes. Anything that's let's cold air in close to the glass is gonna allow for condensation.

[Ocean1]

The next one is going to be as passive as possible and sealed as air tight as possible.

If you thought you had condensation problems with the first two the next one's going to be a ripper.

[Maki]

Condensation depends on two things. (Which themselves depend on a number of other things but let's try to keep it simple.)

1. The dew point of the air inside the house. (In a bathroom this can easily be around 18 degrees if someone is taking a bath or a shower. In that case condensation will form on any surface colder than 18 degrees. Normally the dew point would be a lot lower. Cooking, people in the house, washing dishes will all increase the moisture inside the house and thus raise the dew point. If you have no means of reducing the moisture like ventilation or a dehumidifier it will take very little before you have condensation all over the place...)

2. The temperature of surfaces inside the house. (Dew will settle on surfaces colder than the dew point. This is the reason for dew on a cold glass).

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^

So to get rid of condensation you must address 1 and 2.

1. can be addressed with ventilation and some means of removing moisture from the air inside the house. (This is the reason condensation is normally less in houses that have HRT or DVS systems. You could debate the logic of sucking air through the soffits into the roof cavity and thence through filters before arriving inside the house vs having some windows open from time to time but that is another discussion. (Good ventilation of bathrooms and kitchens is especially important.))

2. Insulation and heating to help surfaces inside the house stay above the dew point. The more insulation you have the less heating you need to achieve this.

[mashman]

If you thought you had condensation problems with the first two the next one's going to be a ripper.

I guess we'll see.

[steve_t]

So that MagicSeal stuff's not the goods then?

[Maki]

So that MagicSeal stuff's not the goods then?

It is better than nothing.

[puddytat]

Biggest differance you'll notice with double glazing is how much condensation youll have on your window.....none.
Damp means mould.....dy

[mashman]

Biggest differance you'll notice with double glazing is how much condensation youll have on your window.....none.
Damp means mould.....dy

That's what we always thought and were told... but not quite true. The brand spankin new houses we've built so far have both had double glazing. The condensation starts on the aluminium, then by morning the windows are all but dripping with condensation... that's on pretty much every window in the house.

[Maki]

That's what we always thought and were told... but not quite true. The brand spankin new houses we've built so far have both had double glazing. The condensation starts on the aluminium, then by morning the windows are all but dripping with condensation... that's on pretty much every window in the house.

The houses need some ventilation...

[flyingcrocodile46]

The houses need some ventilation...

Yes, to replace the moisture vapour saturated air (from breathing, cooking, showering etc) before it starts dropping moisture all over the place when the temperature drops in the evenings. It's not just the visible condensation that is a problem. Moisture vapour diffuses into everything (furnishings, gib, insulation and timber) as it moves through walls, floors and ceilings toward the colder face of the external cladding.

For my money proper heat pumps (with dehumidifiers) and a small amount of natural ventilation, is a healthier alternative to the HRV type systems which are (sometimes) proving to be making things a lot worse (completely destroyed ceilings) and frequently make no difference to temperature or moisture vapour (because the nonces don't understand what they are doing when installing them). All the HRV type systems are doing is moving existing poor quality air from one part of the house to another to another .

[Maki]

For my money proper heat pumps (with dehumidifiers) and a small amount of natural ventilation, is a healthier alternative to the HRV type systems which are (sometimes) proving to be making things a lot worse (completely destroyed ceilings) and frequently make no difference to temperature or moisture vapour (because the nonces don't understand what they are doing when installing them). All the HRV type systems are doing is moving existing poor quality air from one part of the house to another to another .

+1 Agree totally.

[BMWST?]

a mate has had all the windows(timber) removed form his house(the origanal timber frame remains) and replaced with alumiium thrmal break double glazed windows,He swaers by it,his house is def warmer when i visit.