External insulation or windows first

SemperFidelis · 31-10-2012 01:06PM #1

Hi,

I've bought a cavity block house with single glaze windows and no insulation at all. After reading through boards I believe external insulation is the only option for this type of house. I plan to also get some good double glaze windows too.

So my question is from the point of view of the finishing which should I get done first, external wall insulation or double glaze windows. Both will have an impact on the finish around the windows/sills so I'm wondering is there a preferred order.

Thanks

Melendez · 31-10-2012 01:22PM

This post has been deleted.

sinnerboy · 01-11-2012 08:15AM

Windows first most definitely .

They will be losing heat on a per m2 basis , about 3 times faster than the walls are. ( Approx wall U value will be 1.7w/m2K , window approx 5.1 W/m2K).

Assuming windows equate to 25% of wall area you get by way of simplified example ( wall area being 100m2 , windows being 25m2)

100 x 1.7 = 170w/k loss through walls
25 x 5.1 = 127.5 w/k loss through windows.

Despite the smaller area , the rate of heat loss through the windows almost evens the score. Furthermore the heat you lose through single glazing is very sensible by that I mean physically sensible - the human body really feels it. The low surface temperature of the single glazing seems to suck the heat from you.

SemperFidelis · 02-11-2012 01:57PM

Many thanks for the replies,

I'll try get both done together but unless I get a great quote for the insulation it'll likely be windows first then.

External insulation or windows first

Comments