uPVC, Timber or Timber with Aluminium Windows?

[Lucy Murray]

Morning all,

 

Our Timber Frame company has asked us to choose our windows...

 

The choices are: 

uPVC, Timber and Timber with Aluminium.

 

Can anyone tell me a little about the pros and cons of each? Our budget is tight and so from a cost perspective uPVC would be the obvious choice.

 

Thanks in advance,

 

Lucy

[Bitpipe]

From a performance point of view, if the u values are the same then there's nothing in it really from an efficiency perspective, although some frames may be chunkier than others to get the same performance. Note that as the window gets bigger, the glass becomes the dominant effect in the energy efficiency.

 

I'd say the differences are mainly aesthetics and cost - what look are you going for and what style of windows are you looking at? Any sliders, patio doors to take into consideration also?

 

Timber with aluminium will never need painting, will have a broader choice of colours (pretty much any RAL) and generally look pretty sharp. Looks prettier from the inside too and you have a choice of finishes - we went for a fairly cheap wood (spruce) but had it painted with a 50% opacity paint so the grain is still visible.

 

In the basement we have UPVC with aluminium that matches the timber windows and you'd never be able to tell from outside. As the windows are high up, the white plastic frames are less noticeable (and these are occasional / functional rooms).

 

You can get uPVC that has a coloured foil (if you don't like the traditional white) - not sure if the modern uPVC still suffers from the 'yellowing' problem that it used to have.

 

Plain timber will look good inside and out but will need paining on the exterior and continued maintenance. However, unlike uPVC and aluminium, you can change the external colour if you ever wanted to.

[Ferdinand]

Hi @Lucy Murray

 

Someone on the forum wrote favourably of the look of dark coloured upvc. In that case grey.

 

My estimate of lifetimes is:

 

UPVC - 20-30 years

Softwood - 20-30 years.

Aluminium on Wood - 40-60 years.

Hardwood - 40-60 years.

 

With appropriate maintenance, which is more extensive for wood.

 

Depends on how it is treated, and weather conditions etc, and there are exceptions on both ends of the range.

 

Do others agree with those numbers?

 

For budget reasons, I would say make sure to get quotes from independents as well as nationals, and see if you can trim costs by small specifcation changes.

 

There are a couple of threads around trying to compare costs, and it can be +/- 30-50% for not incomparable windows. Wood style finish to the UPVC is 25% to 50% more on the frame element of the price.

Edited May 8, 2017 by Ferdinand

[Gone West]

IIRC Accoya softwood has a 50 guarantee. I think there is probably the largest lifetime range with softwood than any other material.

[AliG]

Hi Lucy,

 

It is not clear, but it sounds like the deal you have is that the timber frame company supply the windows as well as the frame?

 

If so are they giving you a spec for the windows and what is the cost difference.

 

The comments above are correct, so a lot will depend on your budget and your willingness to maintain the windows in the future.

[ToughButterCup]

@PeterW has forgotten more about windows than most of us will ever know. I think he may be on holiday at the moment. Wait until he gets back, Lucy.

Ian

[billt]

Softwood 100 years or more.

 

When we moved here in 1990 the (1920) windows looked to be in a terrible state, putty missing, glass loose, joints coming apart. But closer inspection showed that the wood was in good condition, so I took the opening lights apart, remade the joints, stripped down to clean wood, re-glazed and painted them properly. 27 years on I've started the process of replacing the single glazing with double, which involves removing the opening lights and deepening the rebates. The wood is still completely sound, despite having been repainted only once in 27 years.

[Crofter]

@billt that's very good going and shows that the original units must have been good quality. Our softwood windows are 40yrs old and on at least one the sills are rotting away. Admittedly I've not kept up the maintenance because I am replacing them later this year (they are only single glazed!)

 

When I was researching replacement windows, I was surprised how big a difference in cost it made to reduce the number of individual panes- if you can get away with it from a planning perspective, go for fewer/larger individual panes every time. It cuts the cost, increases the light, and also improves energy efficiency considerably.

[ProDave]

What spec are you looking at? basic double glazed or good triple glazed?

 

When I was looking for good windows I was pleasantly surprised to find Rationel were the cheapest, and almost the best, so it was an easy decision. A lot of folk up here seem to find the same thing.

 

But the question above needs answering. Do you have free choice of any window supplier, or just the few your TF company uses?

 

As to longevity, I chose aluminium clad timber, as painting windows every few years is not on my list of retirement hobbies.

[JanetE]

 I vowed never too paint another window as we have hardwood windows in our current house with glazing bars.  So we went for aluclad upvc from Internorm, plenty of colours to choose from, so we have white inside and cream on the outside. We're very happy with them.

[JanetE]

@billt I also had a house that was build around the same time and refurbished the windows, the timber was in excellent condition despite being a softwood. This was because it was very slow grown, not like the softwood rubbish you get nowadays.  I think it was called Deal.

[MikeSharp01]

I think you can see from the above that choosing windows is not easy. I am going to add a little more by following up what @Bitpipe says above because for us the decision in the end came down to how the windows 'read' from the inside and outside. {By read we mean how it looks - chunky, thin, invisible, & colour because as you move from inward opening to outward opening or fixed panels the inner frame read and outer frame read often change thickness.} If you have inward opening above outward opening you get the frames stepping in and out as you go down the building. With outward opening windows you can thin out the in the internal frame by plastering (or otherwise finishing) right up to the opening frame but on the outside the frame will be chunkier. In some systems the frame is designed to look the same from the inside and out while on others you can have as much as 50mm (in our experience) difference. With inward opening you can do the same on the outside and take the cladding into the reveal and hide the frame either completely or partially. The chunkiness read is also linked to the material such that if you want very thin contemporary windows then you probably have to go for straight aluminum insulated frames while more chunky styles can be achieved in softwood, hard wood & UPVC with or without aluminum cladding.  Hope this helps.

[CC45]

Upvc with foil on - fools most people, out neighbour thought they were wood.  Left on offcut in brick acid for a few weeks and nothing happened.  The company we used made theirs from black plastic so if they do scratch you dont see white.

[craig]

Just to add to this, frame thickness/depth is important for the frame value (Uf). So larger/chunkier frames tend to be better performing.

 

However, pretty much no matter what window you are using. A good detail will be over insulating the frame externally. So you can hide the frame on outward or inward opening windows. This will leave the opening sash only or a little bit of frame as well.

 

One thing to consider with this method, is if the aluminium cladding extends to the end of the frame, ask the supplier what they do about cold bridging. Most will cut back the aluminium on site, others have systems that don't have the aluminium to the edge of the frame as standard.

 

Internally, you can hide the entire frame of a fixed window but very advisable to keep the glazing bead area visible (if internally glazed) for maintenance reasons (i.e broken glass). An opening window dependent on system, will need a certain amount of frame visible for the window to open fully.