Replacing wooden windows with aluminium

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ann7, Oct 28, 7:22am
Hi there
We are looking to replace old wooden windows with second hand aluminium ones. As it is impossible to get exactly the same size frame, can anyone tell me whether it is easier for a builder to put in a slightly smaller, or slightly bigger window.

martin11, Oct 28, 7:48am
Depends on the cladding .Slightly smaller but they may need wide facings and look ugly .

tygertung, Oct 28, 8:01am
Just remember that aluminium is the second best conductor of heat in the world, so it will make your house cold. Double glazed aluminium windows are only marginally better than single glazed wooden windows.

shanreagh, Oct 28, 8:08am
Oh no!

Why not leave the wooden ones for now until you have enough $$$$ to have double glazed wooden ones or else use the 'poorman's' double glazing film from 3M.

Aluminium windows in frames that used to be wooden look so horrid. They will wipe $$$ off your resale value and make work for the next person who will most likely take them out and put wooden ones back.

My opinion but have you asked others?

macman26, Oct 28, 8:15am
Talk with the builder doing the job before spending money on secondhand windows

martin11, Oct 28, 8:28am
Except for the draughts you get around the timber frames because they do not have seals like alloy windows have

tygertung, Oct 28, 8:46am
One doesn't want to have the house hermetically sealed surely. Otherwise it is going to get too damp inside.

barrie2, Oct 28, 8:56am
If you have to do this get slightly bigger. Then the “mess” where old windows were is covered.

rbd, Oct 28, 10:34am
But there is a good chance you will need to enlarge the opening to fit them, meaning the building framework needs modification. You'll spend hundreds to fit a manky second hand window.

tygertung, Oct 28, 10:57am
I would say enlarging the openings would cost thousands, not hundreds.

tegretol, Oct 28, 11:41am
Or even better - retain the existing frames and get double glazed units retrofitted. The dollars on that idea do stack up (that is unless your existing ones are stuffed).

ann7, Oct 28, 12:43pm
Thanks for all the feedback. There are four small windows in a very old wooden sleepout. Its round the back of the house so we are not so concerned about looks. We will get a builder to have a look at what can be done in the existing frames. One is crumbling, one has partially rotted frames, maybe can be repaired. From what everyone has said, it would be a huge job to replace with second hand aluminum windows
.

stevo2, Oct 28, 1:49pm
^^This.^^
Its often dearer to pay a builder to alter the house to fit second hand windows than it is to buy new windows made to measure.

shanreagh, Oct 28, 4:01pm
Might be easier and cheaper to go to a demolition yard and get older timber windows complete or frames.

trade4us2, Oct 29, 8:30am
This.
I did manage to make a new wooden sash to match a rotten one, but I won't be doing that again. The glazier noticed the difference.

blueviking, Oct 30, 1:57am
Don't forget to completely Seal underneath the aluminium windows and have a good flashing underneath as aluminium windows leak badly.

martin11, Oct 30, 2:04am
Aluminium windows do not leak badly it is normally the lack of flashings and the use on Silcone instead of doing the job installation properly

tweake, Oct 30, 12:04pm
they all leak, which is why you have the window opening drainage and water protection.

original_fatman, Oct 30, 12:39pm
DO NOT DO AL WINDOWS!

They suck suck suck!

blueviking, Oct 31, 3:06am
So if Ali windows don't leak, why all the legislation for having sill flashing and cavities where they're used? The only trouble with wooden windows is if some monkey painter fills the drain holes with no more gaps"cause it looks better"

blueviking, Oct 31, 3:08am
Have a look at a product resene sell called dryflex. It's expensive, but not as expensive as replacement windows.

tweake, Oct 31, 5:57am
+1
also they seal up the drainage plain and weeps on alu windows in an effort to "stop it leaking" which of course makes it leak into the house.

bryshaw, Nov 6, 12:45pm
Changing to ally costs thousands but we have noticed on windy nights the curtains don't move anymore. With a pvc film on the glass and heavy drapes the windows keep the heat in fine.

don735, Nov 6, 3:57pm
you talk crap big time, yes aluminium will contuct moisture nowhere to the degree you are talking about, as for the comment double glazed aluminium windows are only marginally better than single glazed wooden windows is so misleading your post should be deleted. guessing you are a deck jockey not a tradie

tygertung, Nov 7, 1:43am
Yes, I am a "Tradie", actually an Aircraft Engineer.

OK, I was mistaken on the Aluminium being the second best conductor of heat in the world. Other substances such as diamond are better, but it is the second best common metal. Aluminium is still an excellent conductor though, which is why it is so popular for heat sinks.
Gold and silver are also better, but it is unlikely that someone would make a window frame out of these materials.

https://www.metalsupermarkets.com/which-metals-conduct-heat-best/ According to BRANZ, the double glazed aluminium windows will have an R value of R0.25, and single glazed wooden window frame have an R value of R0.19. The difference is R0.06.
Thermally broken aluminium is better at R0.30, and timber(wood), uPVC or fibreglass are best at R0.34. These figures are for 4mm glass and a 8mm air gap.

See here for my references.
https://www.buildmagazine.org.nz/index.php/articles/show/window-selection-balancing-act

http://www.level.org.nz/passive-design/glazing-and-glazing-units/glazing-options-for-temperature-control/

Whilst I might not be a joiner by trade, I can read a chart and interpret data as part of my trade training.