Aluminium Double-glazing

[seank]

I am looking to replace an old SG kitchen window with a DG unit. However, the advantage of my existing metal window is that there is maximum glass and minimum window frame to obscure the view of my garden. UPVC frames seem to be extremely thick in comparison and I am not a big fan of plastic windows because of their environmental impact!

Are the frames of aluminium framed DG windows significantly thinner than a UPVC equivalent? Are there any additional disadvantages in installing aluminium framed windows? I have heard they are significantly more expensive than UPVC.

 

[Glassman]

The simple answer is yes. Aluminium windows are gernerally a lot more expensive than UPVC and they are just as bulky as their UPVC counterpart.
The main reason being because all windows nowadays have to comply with doc L of the Building regs for Heat Insulation and Aluminium windows need to have "beefed-up" Thermally broken frame sections to meet this criteria.

A lot of people will argue that Aluminium windows are more resilient to a break-in provided that they are fitted with Shoot-bolt Locks but to be honest I've personally yet to see a UPVC window casement that has actually been prised open with a crow bar. Burglars usually opt to try and break through the glass units or deglaze the window if the beads are on the outside.

Remember - you will get more condensation (not less) if you have double glazed windows. When you cook, the moisture in your kitchen still needs to escape and fitting double glazed windows effectively makes the room more "airtight" hence more condensation than you had before. You'll need to have Trickle Vents fitted to the window to help reduce this.

 

[seank]

Great answer, very useful, thanks

And it is useful to know to ask for trickl vents, I had a feeling they would be essential

 

[Diyisfun]

I thought trickle vents were now mandatory

 

[Glassman]

I thought trickle vents were now mandatory

They are but I know people who've fitted their own windows with Low E glass etc but havent bothered with trickle vents.
I suppose you cant expect the average DIY-er to know everything and Im suprised how many manufacturers still only offer trickle vents as an extra.

 

[biffvernon]

Sorry to disagree with Glassman but trickle vents are not mandatory. They are just one of the the methods given in the Buildings Regs Guidance to allow you to comply with the Buildings Regs Requirements for ventilation. Guidance is guidance and Requirements is the law. Don't get them muddled. There are other ways of ensuring sufficient ventilation such as air bricks and passive stacks. I make bespoke oak windows and would never fit a trickle vent in the frame.

All other things being equal, double glazing produces much less condensation on the glass than single glazing. Its a function of the temperature of the glass being below the dew point or not. The inner pane of a double glazed unit is usually much warmer than a single pane on a cold day. Whether the window is leaky round the edge is wholly to do with how well it fits and the effectiveness of draught strips and has nothing to do with whether there is one sheet of glass or two.

The alternative to aluminium, plastic and wood is steel.
Look at The Cotswold Casement Company and other in This List

 

[Glassman]

Things can start to get very complicated when you start to take in considerations such as air-bricks and wall/ceiling mounted electric fans.
Im not 100% sure but I have heard that there are to be more changes to Doc. F of the building regs. Just to make life even more complicated.

Heres a bit of useful info that might help though in the meantime
LINK: http://www.vent-axia.com/sharing/partf.asp


If you dont already have an airbrick or wall mounted fan it is cheaper and more practical to just pay a couple of quid extra to have a trickle vent fitted to the head of the new window.