"Slimline" 14mm Double Glazing: Worth it?

[Woody3]

We are about to install windows in our newly built extension.

CO says we can either use 4mm single glazing or 14mm slimeline double glazing.

I've 19 windows and the total cost increase to use the DG units will be around £600.

Secondary glazing would be considered, but I'm yet to find an installation that looks nice. From the ones I've seen they usually look worse than DG units...

Thoughts?

 

[88v8]

There was a lot of discussion about dg last year.
The units tend have a short life/high failure rate.
Otoh they don't steam up in the winter like single glazing.

Financially they're probably, no, almost certainly, not worthwhile, but one aspect of 'old house' living I really don't enjoy is mopping the single glazing every winter morning, and I'm guessing that in relation to the total cost of your extension, £600 is nether here nor there.

Ivor

 

[malcolm]

£600 on-cost sounds cheap. I've been quoted that for each secondary glazed window. I'm leaning towards having some double glazed sash windows made for my place with the thin secondary glazing to replace non-original windows. I'd go for it at that price.

In a modern plastic window the edge of the double glazing is vented, but on wooden windows generally isn't. That increases failure rate, and I'm hoping to sit the bottom of my glass on plastic spacers for venting. Also traditional putty very quickly destroys the secondary glazing seal and special stuff is needed.

 

[Keithj]

Secondary double glazing is 'orrible. I've got one panel on a large window, and wish I'd argued a bit longer and gone for DG.

In three years, we've lost one DG panel (out of dozens) to a failed seal. That was an old, reused unit. The manufacturer of the new ones gave very precise instructions as to how they were to be installed, and the rep came and checked them before "releasing" them to us.

The CO wanted us to use krypton-filled ones, but the price was prohibitive. Since most of the rest of the house had standard DG units...

 

[88v8]

In three years, we've lost one DG panel (out of dozens) to a failed seal. That was an old, reused unit. The manufacturer of the new ones gave very precise instructions as to how they were to be installed, and the rep came and checked them before "releasing" them to us.

What make are they?

Ivor

 

[Keithj]

Dunno. The builder chap sourced them.