Debunking The Mysteries Of Misted Up Double Glazing

WHY DOES DOU­BLE GLAZ­ING MIST UP?

Dou­ble glaz­ing is formed from two panes of glass sealed togeth­er, with a gap left between them, to form a dou­ble glazed unit. The air trapped inside the win­dow (or gas depend­ing on the rat­ing of dou­ble glaz­ing you have fit­ted), cre­ates an insu­lat­ing bar­ri­er that keeps heat in.

It is only when the seal on the glass breaks or fails as is known in the indus­try that con­den­sa­tion gets into the win­dow, result­ing in a mist­ed up win­dow. The seal can break for a num­ber of rea­sons but is main­ly due to the age of the win­dow and how it was man­u­fac­tured (the seals don’t last for­ev­er), how it was orig­i­nal­ly fit­ted and any chem­i­cal clean­ing mate­r­i­al used on the win­dow over time that might have dam­aged the seal.

BUTHAVE MIST­ING ON THE OUT­SIDE OF THE WINDOW?

This phe­nom­e­non is a nat­ur­al occur­rence and not a fault in the glass or win­dow, and is not due to your dou­ble glazed win­dow fail­ing as described above. The sit­u­a­tion occurs, main­ly in spring and autumn, when the glass tem­per­a­ture falls to a low lev­el at night, with the mois­ture of a heavy morn­ing dew con­dens­ing against the cold sur­face of the glass. As the lat­est win­dows we fit are more ther­mal­ly effi­cient than in the past, this occur­rence does hap­pen a lot with new­er win­dows. How­ev­er, you do not need to change the glass or change any­thing as it is a phe­nom­e­non of nature.

WHAT EFFECT DOES IT HAVE ON MY ENER­GY BILL?

The Ener­gy Effi­cien­cy Agency states that the aver­age house­hold will save £165 a year on ener­gy bills if you have B‑Rated win­dows fit­ted. A B‑Rated Win­dow (or indeed A‑Rated) is not depen­dent on the frame, but the glass and type of glass you have fit­ted. With the frame mist­ing up, you are los­ing the insu­la­tion the orig­i­nal win­dow pro­vid­ed and more heat will escape, ensur­ing your heat­ing bill will be higher.

DONEED TO CHANGE THE WIN­DOW FRAME?

This is a com­mon mis­con­cep­tion. As a mist­ed up win­dow is due to the seal on the glass, which has noth­ing to do with the frame itself. Indeed, as long as the frame is OK, you sim­ply just need to replace the glass unit. You can even upgrade the glass to A‑Rated ener­gy effi­cient to get bet­ter insu­la­tion and low­er your heat­ing bills even further.

example of misted up double glazing

DOES DRILLING AND INSERT­ING WARM AIR SOLVE THE PROBLEM?

The sim­ple answer is no. With the win­dow mist­ing up due to the seal break­ing, even if you drill the win­dow and blow warm air into the win­dow to clear the con­den­sa­tion, the seal on the win­dow is still bro­ken. Unless the seal is replaced, con­den­sa­tion will still get into the win­dow. Hav­ing this type of repair may well appear to fix’ the win­dow for a few months, it will nev­er tru­ly fix the win­dow and you will have to repeat the repair a num­ber of times over the year to clear the mist­ing of the window.

As the seal remain bro­ken with this type of repair, you will also lose insu­la­tion and spend more on heat­ing bills as the air trapped in the orig­i­nal win­dow is no longer there as the seal is broken.

WHAT ABOUT REPAIR­ING THE UNIT MYSELF?

You could look to repair the unit, but unless the process involves tak­ing the unit apart and replac­ing the seal, you will still have the same prob­lem. It may also become an issue when you come to sell the prop­er­ty, as unless you have FEN­SA cer­ti­fi­ca­tion for the win­dows, you may con­tra­vene UK build­ing reg­u­la­tions in doing the work yourself.

If you use a rep­utable com­pa­ny, you should also get a five-year guar­an­tee on the replace­ment glass unit, so if it does break again, you can get a replace­ment for free.

OUR REC­OM­MEN­DA­TION

If your win­dow suf­fers from mist­ing and con­den­sa­tion between the two panes of glass, the mid­dle bit, then you real­ly should replace the glass unit to main­tain an ener­gy effi­cient home. There will always be quick fix­es’ on the mar­ket, but with a bro­ken seal, the only way to repair it is to replace it and get a guar­an­tee of work­man­ship to pro­tect you should it fail in future. Don’t be fooled by some stat­ing that you need a new win­dow frame – you could even upgrade your home to A‑grade ener­gy effi­cien­cy rat­ing just by chang­ing the glass. But do make sure you always use a FEN­SA reg­u­lat­ed win­dow fit­ter so that you don’t con­tra­vene UK Build­ing Regulations.

Here at Evan­der, we’re hap­py to come out to your prop­er­ty free of charge to sur­vey your dou­ble glaz­ing. If you’re inter­est­ed in arrang­ing a free sur­vey, or would like to chat with one of our experts then sim­ply fill out the form below and we will get in touch.

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