Which wooden windows?

[KellyC]

Hi All

We finally got planning permission for our little extension today so I can stop just trawling the internet and start making some decisions!

Our existing cottage (Victorian - 1859) has PVC windows with Georgian bars. We're going to use wooden windows in the extension and will replace the existing PVC with the same, now if we can afford it or later down the line if not. It's difficult to find anything similar to our cottage locally to compare but I've been keeping my eyes peeled and the Georgian bars look to be what's used elsewhere so we'll stick with these. We have a limited budget and very little knowledge about wooden windows (only what I've managed to find on here really) but we've been looking at these:

http://www.inputwindows.co.uk/cheriton.html

They have quoted us approx £340 p/m2 in laminated softwood ('unsorted quality Redwood of the better marks') with a moisture content of 17% (I have no idea what this means or whether it's relevant but there you go!). They can also do the windows in hardwood (Sapele with a moisture content of 15%) for an increase in price of 18% and have said they can provide monkey tail handles for an extra £10 p/handle.

As I said I know nothing, so will not be offended if these are awful but I would love some impartial advice. If these aren't up to much then can anybody recommend an alternative supplier / which wood we should be using etc. A builder friend advised us that hardwood would split but this goes against everything I've read elsewhere which says it's superior to softwood so that's confused me too!

We also looked at this company/window:

http://www.windowmerchants.co.uk/products-and-services/flushfit-windows.htm

They were around 25% more expensive but I don't have any more information regarding the type of wood etc yet.

Thanks in advance
Kelly x

 

[middi]

Realistically there are about six types of materials one can use for window framing construction:- softwoods, hardwoods, plastic, metal, alluminium and a combination of materials of any of the above and (obviously) glass.

First of all you decide what design is appropriate for your particular situation, then you decide which material is to be used ( bearing in mind the environmental inpact) and finally longevity of materials to be used and ,last not least, the size of your pockets.

Usually if a property is listed or in a conservation area the decision would be very simple as you would be guided by a conservation officer, and in your case it would more than likely be painted softwood with perhaps hardwood cills ( also painted).
Plastic, metal or alluminium and combinations of these are very good materials for someone that does not care too much about environmental issues, they are mass produced to meet current regulations and best of all very easy maintainance ( if any)
Engineered wood ( or laminated strata's of woods) ,as used with modern glues, are very stable when primed and painted, also these are dried at the correct moisture content levels. ( 15 to 18 per cent moisture content levels are the ideals for the English climate when overpainted for exterior use).
Softwoods ( usually joinery grade pine) is reasonably cheap, quite traditional and of resonable long life if looked after.
Hardwoods are extremely good for window framing and, depending on choise, very long lasting. Most of the hardwoods, including sapele, used for window making are imported from the Far East and not very traditional for Victorian window making . Mind you when painted only your pocket and your conscience knows the fifference.
Our English Oak is extremely good for window framing when correctly selected and either air dried or kiln dried at the correct moisture content levels would be the best choise, albeit not the cheapest to start with.
The choise is yours.

 

[Jill]

Hi, We had wooden windows manufactured last year which are made out of idigbo, we looked at a number of wood options and chose a manufacturer local to us who provided a factory finish using sikkens products. Various widths of glazing bars are available and double glazed units that can be individual panes or one large unit which allows for smaller glazing bars to be attatched on the outside of the glass. One guy who worked alone took us round in his van to show us various window options but said that he didn't think he would be able to make them all to a particular deadline which was not good for us so that is why we went for a larger company.

 

[biffvernon]

Please don't use tropical hardwoods. It' really is time we stopped destroying the rainforests.

You say you want 'Georgian bars'. Reproducing the profile typical of 19th century windows just doesn't work with double glazing. The bars have to be wider to allow sufficient rebate to cover the spacer and sealant that holds the two panes of glass apart and seals them. Many of the factory made softwood windows tend to have glazing bars that are 40mm or more across - or they are fake bars glued onto the surface of a big glazed unit. I only use oak for window making and the strength allows the bars to be about 32 mm across. It's a compromise between elegance and practicality. It works fine for a more Victorian style when larger panes of glass became possible, but with the small panes found in older cottages you do get a bit more wood and less light. This can be compensated for by using relatively thin sections for the frame, again an advantage of using oak. My position when making windows with double glazing is to design something that looks good, creating a 21st century style, rather than trying to reproduce period features but failing because the technology is different.

 

[KellyC]

My position when making windows with double glazing is to design something that looks good, creating a 21st century style, rather than trying to reproduce period features but failing because the technology is different.

I like that, thank you! Our windows aren't small as far as cottages go (the downstairs windows are all 1.6m wide) so loss of light isn't a huge worry but we'll definitely look at the design of the bars based on your comments and just try and come up with something we like the look of!

Thanks all for your other comments, all extremely helpful.

Kelly x

 

[JoceAndChris]

You say you want 'Georgian bars'. Reproducing the profile typical of 19th century windows just doesn't work with double glazing. The bars have to be wider to allow sufficient rebate to cover the spacer and sealant that holds the two panes of glass apart and seals them. Many of the factory made softwood windows tend to have glazing bars that are 40mm or more across - or they are fake bars glued onto the surface of a big glazed unit. I only use oak for window making and the strength allows the bars to be about 32 mm across. It's a compromise between elegance and practicality. It works fine for a more Victorian style when larger panes of glass became possible, but with the small panes found in older cottages you do get a bit more wood and less light. This can be compensated for by using relatively thin sections for the frame, again an advantage of using oak. My position when making windows with double glazing is to design something that looks good, creating a 21st century style, rather than trying to reproduce period features but failing because the technology is different.

I really enjoyed that summary of your windows Biff and think it's a highly sensible approach. I didn't realise that many of the factory made glazing bars are 40mm, and yours are 32mm. As a point of comparison, my Georgian glazing bars dividing the diamond shaped panes are 12mm and the Viccy ones are 17mm. Does current legislation allow you to reproduce that, without double glazing? Do your green politics prevent you from making non double glazed windows?

By the way Kelly, don't know if you are anywhere near Biff but his windows really are lovely.
http://www.biffvernon.freeserve.co.uk/oak_works.htm

 

[Penners]

I'd echo that. Biff does fine work.

 

[Ian Bond]

I'd be very wary of fitting lots of individual sealed glazing units.

Lets say you've got 8 sash windows, each with 16 panes, that's 128 units. How long until they start failing and need replacing? You're going to be continually messing around with the windows over the years replacing the glass.

It sounds like a potentially expensive and wasteful exercise. It may be OK if you only have 2 units per window, but that's not much good if you're trying to conserve a period building that demands elegant, multi-paned windows.

It's poor design, and built in obsolescence. Single glazed windows with shutters, or even secondary glazing would be far more durable and possibly sufficiently energy efficient.

The following links discuss conservation of old windows. But for historic buildings the same principles should apply. If the arguments are good enough for existing windows then why not for replacements?

http://www.english-heritage.org.uk/server/show/conWebDoc.3428

And

http://www.climatechangeandyourhome.org.uk/live/research_generic.aspx

 

[biffvernon]

If it's a listed building or in certain Conservation area you may have to have single glazing. Otherwise, the Building Regs pretty much force you to have double glazing (assuming you don't want to be an outlaw).

That's nothing to do with green politics, Joce, just the rules. I love making windows with single glazing and hand made glass, clear or stained. For sure there's a planet that needs saving but that's about not emitting CO2. Whether one's windows are double glazed or not is quite far removed from one's carbon footprint. You could have triple glazed windows, forget to close them, turn the heating up and then fly to Australia. Or you could have the most beautiful historic glazing, wear thermal underwear and only walk or bicycle.

Ian, on the double glazed unit sealing failure front, I've used the same unit design and manufacturer for the last six years (cheaper one's may be available). They come with no guarantee from the factory and I give no guarantee to my customers and I really don't know how long they will last. But I do take care to install them in a way that I think maximises their longevity. I've put well over a thousand of these units into my windows and so far, to the best of my knowledge, not a single one has failed. I'm sure someone will come back to me one day but it hasn't happened yet. I have 112 small units in my own house so I wouldn't be shy of using them at all.

 

[Ian Bond]

However, I've got panes of glass in my house that are 170 years old, and still OK for another 170 years. Excepting accidental damage, or someone ripping them out to fit uPVC.

My point is that double glazing is not necessarily the best solution, whatever the current building regs may say.

I remain to be convinced otherwise.

 

[Flyfisher]

Secondary glazing seems to be a generally well-accepted solution to improve thermal performance but what about 'secondary windows' ? What I mean is an additional window frame complete with inward-opening frames fitted with DG to the latest regs.

I'm sure they wouldn't work everywhere but many of our SG casement windows are set within 12-inch thick walls and it would be very easy, and completely non-destructive, to install a new frame in front (or behind?) the original, leaving the original SG window completely untouched. The new DG units would allow the latest regs to be met, the original windows would remain untouched and the fairly large gap between the two windows would do wonders for noise reduction.

Just a thought.

 

[JoceAndChris]

That's an interesting idea FF - wouldn't work here with the deep recesses and shutters, but it could elsewhere.

The following links discuss conservation of old windows. But for historic buildings the same principles should apply. If the arguments are good enough for existing windows then why not for replacements?

http://www.english-heritage.org.uk/server/show/conWebDoc.3428

And

http://www.climatechangeandyourhome.org.uk/live/research_generic.aspx

Those links cheered me up- thanks.

That's nothing to do with green politics, Joce, just the rules.

That didn't, but thanks for the clarification.

This nonsensical double glazing rule makes me want to tear my hair out- it puts people like me in an unlisted building in the most awkward situation. Either I break the law, and ask the window maker to break the law, or I wreck the harmony and symmetry of the house by putting in a different, and non-matching, style of window when replacements are needed. And how could the glazed porch with the 12mm bars be put back as it was? It couldn't . Maybe this is further argument for me to get the house listed if it gives it the best chance of appropriate windows.

 

[Flyfisher]

Joce, you're in the same position as Skier-Hughes and I think his house is 17-something but unlisted. As you rightly say, it's a difficult situation, but I wouldn't bank on being able to get the house listed.

 

[JoceAndChris]

Indeed not. In my opinion it's completely unique and unutterably precious, but I'm well aware that opinion counts for not a lot. And, if it were listed, they might list the blocked up windows and not want me to unblock them anyway, or list the porch as it is and not want me to change that - so I can't win, unless I just be content with things as they are, which seems a shame, when they could be better.

Sorry if that was girl's logic!

 

[skier-hughes]

it was 300 years old in 17 something, well some of it was........

Yep, I fought the BC dept as they told me to give thema convincing plan for why I should have single glazing, so using many arguements given to me by the CO, and a fair few I thought of on my own, a three page document went on it's way.

The answer that came back was no.

I telephoned for clarification as to why......... "Well John Prescott says you have to, so you have to."

I am replacing old 1970's aluminum DG, so my CO thought it would be a struggle, and felt a good plan might win, but.........

 

[JoceAndChris]

Oh, dear. I'm in blood-boiling corner here with this issue. Does that mean on your lovely house you have some new, double glazed sashes and some original windows? Or have you replaced/will you be replacing the whole lot? If the first scenario is the case, how have the new ones blended in? Sorry if you've covered all this ground before on here, but some how I think I missed it.

 

[biffvernon]

The world is not going to come to a sudden stop if you live the life of an outlaw, and unless you're selling the house soon I'd guess nobody will be the wiser or care. Not abiding by Building Regs is not a criminal offence (unlike contravening Listed Building Consents) so you'e not going to end up in the Tower.

When we replaced the 1960s crap windows in our 1750s house we put in double glazing but we thought long and hard about the design, looked at old photos of the place from the 19th century, looked at similar houses in the neighbourhood, and made windows which we thought did justice to the building and that we liked. They're untreated, unpainted oak with double glazed units. We are warmer for less fuel. We do have one original window round the back, single glazed and mostly held together with putty and paint. I'll keep repairing it and never replace it. It's on a staircase that is not a heated room so heat loss is not so great. And there are thick curtains.

Every case has to be judged on its merits and it's bad to think that one rule fits all, but I would always start by recommending maintenance, then repair of historic fabric rather than replacement. Sometimes I've made like for like exact copies of what was, mostly so that discordance with the rest of the building is avoided, but my default position is to avoid the fakery of replicas and so more often I've found it better to replace with well designed double glazed windows that keep you warm, keep fuel use low and yet still look great. It can be done. We should be able to develop a 21st century style that will be valued in centuries to come. There's still a chance that civilization will survive if we all do our bit.

Obeying the rules is the least important factor.

 

[MdB]

... But I do take care to install them in a way that I think maximises their longevity. I've put well over a thousand of these units into my windows and so far, to the best of my knowledge, not a single one has failed.

If you don't mind sharing some of your trade secrets, can you expand a bit on what you do? I would say 50% of our 14 year old windows have failed....

 

[biffvernon]

No trade secrets. I think much may depend on the factory that makes them. I did build a conservatory about 20 years ago and most of the units failed within a year but not until the firm that made them had gone bust!

So start with well made units - they probably mostly are these days as fabricators have learnt what works. I usually use 4/16/4 argon fill low-e glass with insulated spacers from Spire Window Systems of Louth. My frames are untreated oak. The units are held in with double sided pvc foam 12mm wide 3mm thick glazing tape, available from Industrial Tapes Ltd of up north somewhere on Tyneside, and on the outside an oak bead about 13 or 14 mm squareish, mitred corners, a tight fit, held in with glue and brass panel pins. I add a bead of builders' silicone to the visible edge of the tape on the outside connecting wood to glass. I don't bother with drain holes and air spaces. There's a bit of an air space anyway as the unit is never an absolutely tight fit, drain holes always get blocked and it's better to keep the water out in the first place. The wood is permeable so if water did get in it could dry out again. Never use a low vapour permeable paint.

That's about it.

 

[JoceAndChris]

The world is not going to come to a sudden stop if you live the life of an outlaw, and unless you're selling the house soon I'd guess nobody will be the wiser or care. Not abiding by Building Regs is not a criminal offence (unlike contravening Listed Building Consents) so you'e not going to end up in the Tower.

Every case has to be judged on its merits and it's bad to think that one rule fits all, but I would always start by recommending maintenance, then repair of historic fabric rather than replacement. Sometimes I've made like for like exact copies of what was, mostly so that discordance with the rest of the building is avoided, but my default position is to avoid the fakery of replicas and so more often I've found it better to replace with well designed double glazed windows that keep you warm, keep fuel use low and yet still look great. It can be done. We should be able to develop a 21st century style that will be valued in centuries to come. There's still a chance that civilization will survive if we all do our bit.

Obeying the rules is the least important factor.

Thanks so much for that wonderfully lucid explanation. And your house is beautiful, with the windows really taking centre stage - gorgeous.