Aluminium and Hardwood Windows and Double Glazing

Ask an Expert - Hardwood/Aluminium

Please note: Most of the answers we feature here are from 1999 - early 2002. We endeavour to keep all links etc up to date, however if you spot any errors please let our webmaster know at It should also be noted that some replies may change in light of changes to legislation especially with regards to Planning Permission and Building Regulations. To submit a new question or to query an existing question visit http://www.ask-questions.com/yabbse/index.php.

Ref:04
Question submitted by John

We've recently had PVCu Windows fitted with Diamond Lead effect. We were expecting that the diamond Lead would be installed between the double-glazed panes but instead it is on the outside of the window which is exposed to the elements. This already appears to be causing discoloring of the Lead. Were we right to expect the lead to be in between the double-glazed panes or is it standard for it to be on the outside?

This question answered by the Windows Today editorial team - Its normal for the lead to be fitted externally and exposed to the elements. On occasion the lead will "oxidise" as it "ages" resulting in "white streaks". Over a period of time this will usually stop (approx 6 - 12 months) Eventually the lead will adopt a slightly duller appearance - this is quite normal. In the meantime we have been told that applying a mild solution of washing up detergent will often help remove the initial staining. Be careful not to scratch the lead too much when doing this. We suggest you speak / confirm this with your supplier prior to application.

Ref:03
Question submitted by Lucia

I am a bit confused about the different type of frames available on the market. Whereas hardwood is pretty self-explanatory, aluminium and PVCu are more confusing. For example, we have seen frames, which are aluminium on the outside and PVCu on the inside. The salesman says they are good in terms of insulation and the inside does not get too cold, thus making it less susceptible to condensation but in your web site and other brochures we have seen always give the option of either aluminium or PVCu. Can you clarify this point please.

This question answered by Tina Dunlop @ Almost Impartial Guides - About 10 - 15 years ago the "thermal clad" option - combining both aluminium and PVCu was quite popular. Today only a few companies still do it. The reasons for this are most likely both "political" and "economic" in that most Aluminium Extruders didn't particularly want to promote PVCu as an alternative (preferring to promote a thermal break option) and PVCu extruders did not particularly want to promote Aluminium. Speaking personally "thermal clad" aluminium framing would not be my preferred option. This does not mean you should not consider it - especially if you like its looks. It's a perfectly good option to consider along with PVCu, Hardwood and Aluminium. Like all the material options - it's a matter of personal choice. It might also be worth remembering that quite a number of the conservatory roofing systems use a thermal clad system for the roof rafters - i.e. Aluminium Roof Rafters - Clad in PVCu - so at least in terms of roofing it is not unusual. What really matters is finding a reputable supplier and installer who can do "justice" to whatever material is used. Your experience is quite unusual in that you have come across this product. As you say few brochures and this web site did not even mention it as an alternative. At least your question has corrected that omission on this web site. Thank You.

This Question answered by Tina Dunlop @ Almost Impartial Guides - Red Cedar (actually a type of softwood) is a perfectly fine material for windows or conservatories. It is no better nor worse that a suitable hardwood and is also similar in cost. When selecting hardwoods it is generally considered best to use a "close grained" alternative such as IDIGBO. This hardwood machines well plus is very strong and durable. You may wish to ask your potential suppliers about the "closeness of the grain"! I would say West African hardwood from sustainable plantation sources is probably the most popular of the Hardwood alternatives.

This Question answered by Tina Dunlop @ Almost Impartial Guides - I am familiar with this product. For assistance in answering this question I consulted David Salisbury of David Salisbury Conservatories (www.dscons.com). Whilst David could hardly claim to be impartial I think you may find his feedback of interest in any case. Here is his reply. "Mitred joints as you describe have been widely sold. Many joiners would argue that this is an inferior system because mitred joints inevitably open up when the wood expands and then water is allowed into the joint (note what happens on a mitred timber sill). While it is true that a mortice and tenon joint on a casement exposes end grain this will not be a problem if factory sealed. Argument could rage between partisan opinions on either side, but it is not true to say that the mitre is a clearly superior system, and most traditional joiners would disagree. "Speaking personally - I do not care for the method you describe in your question. It has been primarily designed for speed and offers a similar manufacturing process to mass-produced PVCu windows. It does not for me have that feeling of "authenticity" and you will not have that "bespoke" feel because your supplier is more limited in the range of sections they can use. (It's all based around standard sections.) Unless it is considerably less expensive than a traditional mortice and tenon approach I would not favour it.