On Friday, 20 May 2016 09:40:21 UTC+1, Tim Lamb wrote:
In message ,
tabbypurr writes

Six new windows are required for the alterations so current thinking is
to go for new throughout. First estimate for 12 windows and two doors
came in at 18K fitted. This afternoon was spent trawling round the local
showrooms. I'm not much wiser:-( The much vaunted narrow mullion
aluminium does not seem to exist. By the time they have put in the
plastic thermal break and endless folds for strength and appearance they
are as fat as uPVC.

Why replace the existing windows? Just fix them like for like if
they're misting.

Elsewhere, the architect has specified 4-20-4 argon filled. The existing
window rebate is much too narrow. Also new windows will be visible on
the frontage and jar with the existing.

You can specify what you like, as long as it meets BR.


Thoughts please. Does uPVC really stay clean and shiny for 20 years?

the gloss goes & it becomes somewhat uncleanable. If facing onto a
street there's also a slight risk of cigarette burns. I'd plan on a set
of windows staying for a lot longer than 20 years!

Isolated plot, set back from the highway.

With new PVC I'd go for external glazing. The advantage is that when
the sealed unit seals fail (not if), they don't mist up & don't need
replacing.

Please enlarge. I thought the only difference was whether the burglars
could prise them out.

That's the usual reason quoted for internal glazing, but imho it's a bit of a false one. External glazed windows use glazing tape, a very tough adhesive that prevents that. To get in you'd need to take the same measures required to enter through internal glazed windows.

Unsealed DG mists because the inner space is exposed to the same water vapour level as indoors, but the temp is lower. Expose that space to the lower outdoor water vapour levels and it simply does not mist. External glazing does the latter, internal glazing the former.


Have you considered new durable species timber windows to match the
existing? (but with deeper whatsits.)

Not yet. This will be out last house and I am trying to avoid
predictable maintenance.

hence I said durable species.

If you go for ali windows, beware of colour finishes such as powder
coating. Nothing sticks well to ali, lumps come off in time. They only
reliable way to colour ali is anodisation.

OK. There doesn't seem to be a raft of disgruntled powder paint owners
out there.

Well, that's how ali is. Nothing sticks to it forever. Google can confirm.


NT