roof lantern triple glazing worth it?

[andrewf75]

Hi all

We're building a kitchen extension (6x5m) with a large roof lantern (3x2m) and 2m bi-fold doors. So its a high glass area and the walls and floor will all be well insulated etc

My question is:
Is it worth getting triple glazing on the lantern? or is that overkill?

 

[crank39]

Overkill i'd say but others may advise differently, a tinted outer pane with with an active coating if you want and saint gobain planitherm inner with a warm edge spacer should be more than ample

 

[God]

Really don't think you will benefit from it and you will still only get a 28mm unit if using uPVC. A decent Lowe/ argon/ planitherm will do it

 

[crank39]

24mm in roofs isn't it???

 

[God]

Yep , well synseal is, assume the rest would be. Silly me 28mm

 

[andrewf75]

Thanks for the replies.

But why wouldn't I benefit from it?

The triple glazed is 36mm thick and has a u-value of 0.6 whereas the double is around 1.2. For an extra £600 or so is that really not worth it?

 

[God]

Because I would say the roof would not be airtight like a window and heat rises

 

[Gazman16]

To be honest at only £600 extra I would go for it if you can afford the upgrade.
That is quite a large skylight 3x2m is almost a conservatory size in itself and as it is going to be one of the most used rooms in the house you will want it nice and warm.

Im not going to try and work out the calculations but I expect it would pay for itself in heating costs in the long run.

 

[God]

Did not think you would get a 36mm unit to fit in a cons roof.

 

[Gazman16]

The roof glazing bars are about 90mm deep so they would only need to make a different top cap (and a few other PVC bits) to accommodate any size unit.

 

[God]

But do they make them, can't see anyone doing a one off

 

[Gazman16]

I haven't personally fitted one but I have heard about them and I'm sure my suppliers can do it if I ever asked.

 

[crank39]

Most makes of roof i go to look at are either.....

Polycarb 25mm, 32mm, 35mm
Glass always 24mm

Glass roofs generally utilize heavy duty ali rafters to take the weight, obviously some of the bigger roofs also need tie bars, would a lantern roof need tie bars i don't know but to triple glaze one then i'd of probably thought so???

The OP mentioned a triple unit of 36mm, technically you'd used top caps to suit a 35mm poly roof but use heavy duty ali to take the weight of glass, the manufacturer should be able to advise and also give snow loading calcs too

 

[andrewf75]

Yes the lantern will be supported by steels so weight is not an issue. Just wondering whether its worth upgrading to the triple glazed

 

[s60tsy]

i manufacture roofs and we do a roof that can accomodate the 36mm glass units, we have done quite a few. The gains from triple glazing may be lost with the roofs draughts etc. id say get the best dg 24mm glass for the difference in price compared to money saved along time