Aluminium framed windows all round?

[dogfonos]

Would like advice/opinions, please...

We're been advised by our architectural technologist that a large 'feature' window at one end of a room in our proposed build will need to be constructed of either laminated wood or aluminium frames and not uPVC. Haven't had a chance to discuss this yet but I assume it's a strength thing. At the tallest point the floor-to-ceiling window will be just under 4m tall and I can do without maintaining external wooden frames so that option doesn't appeal.

We currently have old style aluminium framed, double glazed windows from the 1980's fitted throughout our property which, in all but one respect, we prefer to current uPVC windows we've seen. However, the one aspect we don't care for is some pretty serious frame condensation - it's a real issue for us most winters. We carefully control moisture levels within the property and I've carried out atmospheric moisture testing in all rooms and can definitely state we don't have a damp internal atmosphere in winter so have concluded that the problem is due to frame cold-bridging (so much for the incorporated 'thermal break').

I don't want to spend a grand (or whatever) on a flashy aluminium framed window only to need to mop the floor on winter mornings. How far have new aluminium framed windows developed since the 1980's with regards to frame cold-bridging? I see there are also window frames available with wood inside and aluminium outside - any good? Whatever window frame we choose for the 'feature' window, I intend to replace all the other windows in the property with the same type/style/colour.

Any suggestions or experiences much appreciated, thanks.

 

[dishman]

Should be a night and day difference.

Aluminium frames have come on a long way. They include thermal breaks which stop thermal transfer from one side to the other. However, as will all things, find out which company is contracted to make them and do your research.

Another option is to get aluminium frames which are timber clad on the inside.

 

[dogfonos]

Thanks dishman, that's good to hear.

Yes, aluminium frames with timber cladding inside sounds like a good option. I'll look into it more.

I know what the inside of my current aluminium frames feel like to the touch on a cold winters day. Maybe as a crude test, I'll take along a bag of frozen peas when I visit window showrooms and check out the frames' thermal performance - come to think of it, I have a contact thermometer lying around somewhere...

 

[dogfonos]

Hi Michal001,

I received an email earlier today that informed me you'd started a 'conversation' on DIYnot with me (entitled Replacement Windows). I've logged in to DIYnot and followed the link to the conversation in the email but I can't find any conversation - a message tells me there are none.

Apologies if you are genuinely trying to contact me and I'm doing something wrong. I've tried to start another conversation with you but, once again, I receive a message that tells me I can't start a conversation with you. I haven't a clue what's going on?!?

 

[Gazman16]

You have said the window will be 4m high at the highest point but how wide? I assume it doesnt need to be structurally supporting at all so It may be possible to do in PVC (maybe with aluminum couplers for support), You just need someone who can do the wind loading calculations I would guess.

Aluminum will always be cold and more prone to condensation. Just touch anything metal in your house like a cold radiator and then a wood or plastic surface to compare. If you already have condensation issues it wont matter how good the thermal breaks are.

 

[Matthew Johnson]

In principle the U-vlaue for aluclad windows is no better or worse than PVC. When it comes to aluclad windows I'd recommend http://ms-woodwork.co.uk/. It's a polish company, good prices and quality.

Cheers

 

[dogfonos]

The window will be 4m high (at tallest point) and 2.5m wide at base/floor, tapering to a point at 4m high. I don't know yet if the window needs to support load - I image that will depend on construction method of the pitched roof above (we'll go into weight loading details when we next meet up with our AT).

Fact is, uPVC wouldn't be my frame material of choice for any windows in our property. Based on strength/rigidity, appearance and sight lines, I'd plump for aluminium (which we currently have). The only big question mark over aluminium is the condensation issue. I've not found any actual measurements of frame thermal performance - only figures for entire windows (frame + glass) where the glass element probably swamps any differences in frame performance - so I'd be grateful for any links to frame-only thermal performance figures.

I know what you mean, Gazman16, about metal surfaces in the home being cold to touch but I think that's a slightly different issue. Whatever surface is in the home, it will be at the same temperature (assuming its been in the place for a while and isn't heated or cooled). Yes, such an aluminium surface does feel colder to the touch but actually isn't any colder than, say, a wooden surface in the same room (i.e. the surface temperatures are the same). The aluminium/metal surface just conducts heat away from the hand better than wood/plastic so it feels colder to the touch. I know it's impossible, but if a window could be constructed where the inner surface was totally thermally isolated from the outer surface then it wouldn't matter what materials of construction were used, there would be no condensation. In reality, it's a matter of degree - sufficient thermal isolation (whatever that would be) between outside and inside surfaces and aluminium frames would be fine. I could possibly read dew points/condensation points from temperature/humidity charts if I have to, but I need frame thermal performance figures to do that and I've not managed to find any.

Sorry for rambling on and thanks for your replies.