Double Glazing FAQ/help.

[wedge69]

Hello,

We have finally saved some money to get double glazing on our 3-bed semi, and I was hoping someone could help.

I don't want to be hoodwinked by any salesmen jargon, so I was hoping some one may be able to give me some advice on terms relating to windows.

For example, what thickness should the gap be between panes in normal domestic insulation? Is it worth paying more for "special" types of glass? What type of locks should be used? What are the name for the vents that allow air in and out without opening the window.

Any help, or a pointer to a FAQ would be gratefully received.

 

[Richard C]

There is a lot of advice already on the forum so you should have a good read back through the archive posts; I’ve pulled together much of the standard stuff here & added some of my personal views & experience.

Very few companies make their own windows nowadays; they mostly come from larger regional factories. The quality of name branded units is generally comparable so its installation quality that makes the difference. You won’t necessarily get a better product/installation from the large national companies but you will probably pay a lot more for the privilege. Get written quotes from at least 3 smaller, local companies & make sure they list exactly whet they are providing; I initially approached 10 but many of those fell quickly by the wayside! Look closely at the quality of the frame welding, fittings & locking mechanisms, ask to see a very recent & much older installation (18-24 months) & make sure you speak to the customer themselves for a reference. Make sure the company includes for any scaffolding needed for installation access - a popular ‘extra’ charge once you’ve committed! Get them to include fitting new, good quality internal cill boards (Pollyboard is good) & they at least include making good externally – internally as well if you want it. Don’t pay more than 20% up front (10% if you can get away with it), don’t pay the balance until you’re entirely happy with the work & get an independent 10 year warranty if you can. Never, ever sign up for a ‘special deal’ on the day – they aren’t special & you’ll probably get ripped off. Get written quotes, ask questions & decide in your own time; if they try & pressure you, cross them off your list!

Double glazed units should be manufactured by a FENSA registered company in accordance with parts F and N of The Building Regulations. 70mm frames, 28mm glazing units with 20mm air gap are the norm, the vents are called ‘trickle vents’. Replacement windows (except conservatories) must have low “e” glass to meet thermal requirements (Pilkington ‘K’), it’s not an option & shouldn’t be presented to you as a extra! Door glass and any adjacent window panels below 1500mm from finished floor level must have toughened glass, as must all windows with a cill height below 800mm. Regulations only require that replacement windows are no worse than the original installation with regard to escape & ventilation so you don’t have to have trickle vents & fire escape windows all over the place (another popular extra!) but obviously these may be desirable in specific locations. The installer doesn’t have to be FENSA registered but it makes life easier & make sure you get the certificate. If non-registered (& there are some good ones), make sure they notify BC about the work, get it inspected & that BC provide the necessary conformance certificate on completion or you could have future problems selling; & make sure the installer pays for it!

 

[wedge69]

Thanks Richard, that's brilliant.

 

[JohnD]

Just to check, you are having new windows because your old ones are rotten and irrepairable?

Money spent on double-glazing has the worst payback in terms of heat saving of any of the steps tou can take (insulation and draughtproofing have miles better return). The marketing and pushy selling of plastic windows has a lot more to do with the profits made by the installing companies than the benefits to the householder.

 

[wedge69]

Just to check, you are having new windows because your old ones are rotten and irrepairable?

Pretty much yes - currently they are all single glazed, wooden frames, and many of the frames are rotten. This was pointed out to us when we bought the house though, so we did know we would have to repair or replace.

 

[Richard C]

Money spent on double-glazing has the worst payback in terms of heat saving of any of the steps tou can take (insulation and draughtproofing have miles better return). The marketing and pushy selling of plastic windows has a lot more to do with the profits made by the installing companies than the benefits to the householder.

I wouldn’t disagree with any of that & good curtains can also be of considerable benefit. But sometimes there are additional reasons to consider replacement. Our previous house had single glazed, lead lights which looked attractive & were in good condition so it wasn’t cost effective to replace them during our time there. The windows in our current property, however, were rotten, draughty & old fashioned with huge 60’s/70’s style non-toughened glass panels so there were additional problems of safety & how the place looked!

We replaced them with sectional windows within the original brick openings & added a front porch under an existing pitched tile roof area. It’s made a huge difference to the house in winter & practically everyone in the village has commented on how much the external appearance of the house has been transformed from its previous tatty & run down state.

 

[rajpatel50]

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lynda, moderator

please read forum rules.

I could not split your post and still have it make sense

 

[jud1967]

The optimal air space is 16mm for insulated glass units.

One pane of glass should at least be Pilkington K but much better than this would be Pilkington Optitherm SN.

 

[wedge69]

We'll we've had two quotes so far, both from local companies recommended by other people. For seven windows, one quoted £2500, and the other £3600.

Now we haev to figure out why the difference in price!

 

[avidfan]

We've just been Quoted EIGHT AND A HALF GRAND for ten windows from Anglian. And that includes their current three windows for the price of two. (This is misleading though, as they count a pane of glass as a 'window' not the whole frame) Beware!