Advice on sash windows

juliecat

I would really like some advice on what's the best approach to rennovating wooden sash windows.

Is it possible to get them double glazed? How far gone do they have to be before the whole unit needs replacing. What kinds of costs am I looking at to replace 4 windows?

Many thanks.

nickj_2

they probably can't be double glazed as the thickness of the d/g would be too big for the thickness of the sash , you would have to get a carpenter to look at them to work out if the cost of repairing them is worth it against the cost of replacing them ,
have a look here -for more info http://www.sashwindowspecialist.com/price.html

Mankysteve

Is the property listed? as this will vary what you can have done.
You cna get modern replacement sash windows with double glazing but as the above post said never seen replacement glazing units.

adrian_bond

i have double glazing in my wooden sash window. very common. i think mine was renovated about 5 years back before i moved in. i had a chap round who wanted to renovate it (it was sticking) and wanted to charge me £1400 for a new window. i politly told him to fornicate himself as it needed freeing with a spatula and some new paint. i did this in an afternoon and it looks great 2 years later!

older type sashes may not be able to take double glazed glass thicknesses (i think its usaualy 2 x 2mm panes of glass laminated with a 4 mm interlayer). please dont quote me on this tho as its only an estimate. i guess your single glazed units would be 4mm single glass. the wood should be thick enough to take some thicker glazing or could be beefed up.

my advice would be to get a few companies round, explain what you want them to do and get quotes. if its just a glass replacement, depending on how handy you are, you may even be able to do it yourself! if you search for threads on the diy forum about sash windows there are loads of posts on the subject. plus i would check the quotes against "is this quote fair" section in the diy forum home page.

hope this helps!

swagman

If the sub-frames and the boxes which hold the sash weights are all in good nick, there are several companies which will manufacture double glazed windows to fit into your frames - in other words you just replace the sliding windows.

Ours were very well done several years ago by "The original Box Sash Window Company" but there are similar firms to be found by googling.

juliecat

Thanks people. We're talking Edwardian, 1910 in Harrow North West London, any tips on reputable people in this area would be great. My rapidly dimming memory seems to remember seeing posts on here in the far distant past talking about 800 quid for a refurb and double-glaze sash. We have 4 needing doing.

Fred56

I've done this in the past. There is limit to the thickness of dougle glazing you can get into a traditional sized sash. On modern replacement box sash windows the thickness of the frame and sashes is much thicker to accommodate the glazing units. I managed to get some 14mm units into a few windows that were in good condition,but I do have the skills and the tools. You have to increase the depth of the rebate substantially. A regular pane of glass is only 4mm thick, a thin DG unit is 4-6-4 = 14mm but a modern DG unit to current regs is overall 22mm. An old style sash sized to take a single 4mm pane will not have enough thickness to take a 22mm DG unit. Also, DG units are heavy and you have to increase the mass of the counterbalance weights. Old box sashes tend to have rather narrow weight boxes too.
If the windows need replacing in total try to go for spring balance types as they do not suffer the hideous levels of air infiltration through the weight boxes. If your windows are otherwise OK, look at secondary glazing. Please don't go all pastic.
Every region has its small bespoke joinery manufacturers. Where we are in North Yorkshire we've had custom made sash windows from two local people and both were fair and did a good job. The big maunfacturers do make them too but in a narrow range of sizes. Make some enquiries and you'll track them down. They are not likely to have a website, you'll have to talk to people at the local timber and builders merchants.

juliecat

Thanks. Definately not going for UPVC. Look terrible.

chrisg1985

Fred56 wrote: »

I've done this in the past. There is limit to the thickness of dougle glazing you can get into a traditional sized sash. On modern replacement box sash windows the thickness of the frame and sashes is much thicker to accommodate the glazing units. I managed to get some 14mm units into a few windows that were in good condition,but I do have the skills and the tools. You have to increase the depth of the rebate substantially. A regular pane of glass is only 4mm thick, a thin DG unit is 4-6-4 = 14mm but a modern DG unit to current regs is overall 22mm. An old style sash sized to take a single 4mm pane will not have enough thickness to take a 22mm DG unit. Also, DG units are heavy and you have to increase the mass of the counterbalance weights. Old box sashes tend to have rather narrow weight boxes too.
If the windows need replacing in total try to go for spring balance types as they do not suffer the hideous levels of air infiltration through the weight boxes. If your windows are otherwise OK, look at secondary glazing. Please don't go all pastic.
Every region has its small bespoke joinery manufacturers. Where we are in North Yorkshire we've had custom made sash windows from two local people and both were fair and did a good job. The big maunfacturers do make them too but in a narrow range of sizes. Make some enquiries and you'll track them down. They are not likely to have a website, you'll have to talk to people at the local timber and builders merchants.

Installing 14mm standard float units is pretty normal and always a good start assuming you incorporate a draught exclusion system.

I assume by mass you mean 'weight' and this is no problem at all because you will use lead as opposed to the old cast iron simply for a better density ratio thus not reducing travel of the window itself. On this note the width of 99% of original single glazed boxes have enough room to house the required counterbalance for double glazed units without affecting travel of the sash much at all

DO NOT go for spiral balances. A poor substitute for traditional cords and weights. The reason your getting a draught from the pulley wheels is simply because the windows you have had installed do not have a backing thus allowing the draught to come through.

Secondary glazing works well but why spend the money on this route if you can upgrade your existing windows without altering the look.

chrisg1985

juliecat wrote: »

Thanks people. We're talking Edwardian, 1910 in Harrow North West London, any tips on reputable people in this area would be great. My rapidly dimming memory seems to remember seeing posts on here in the far distant past talking about 800 quid for a refurb and double-glaze sash. We have 4 needing doing.

That's around the going rate still. You might be able to get slightly cheaper.

chrisg1985

nickj wrote: »

they probably can't be double glazed as the thickness of the d/g would be too big for the thickness of the sash , you would have to get a carpenter to look at them to work out if the cost of repairing them is worth it against the cost of replacing them ,
have a look here -for more info http://www.sashwindowspecialist.com/price.html

Almost any original window can be double glazed.