skylight window

chicobonito

hi I just have reinstalled in the extension (10 years old extension 40m2 open space plan) double glazed low e soft coated units the size of window is 7m-2.4m UV value is 1.0w/m2k. its a flat skylight frameless windows with glass fins.
Problem is we have amount of condensation by the edge on the lower point of the window and along the fins where panels are connected.
things for consideration:
room is quite cold we only heated when we stay there 2h a day more less
we have big sliding patio door poorly insulated lots of draft (we will change them for 0.7 UV value)my question is:
should i be worry about the condensation as because poorly fitted units
or its normal if the room is cold for most of the time and plus there is lots of draught through patio door.
thank you very much for your help
regards

BryanF

Thermal bridge (cold bridge)

Insulation overlap with window frame and air-tightness tape/membrane/sealant is part of the solution


1wm2k = ~20mm polystyrene (eps) .... How much insulation have you in your walls? If you have say 100mm that's ~0.3wm2/k

1wm2/k is a grand u-value for Windows but if you've got ~16m2 of glazing + door

Then you've got excessive air leakage = letting all the heat out.

chicobonito

first thank you for your reply.
So as it comes to sealant they used some sort of tape as you describe plus some liquid rubber on which the window sets.
walls are 30cm included plaster board so i reckon there is some sort of insulation most likely is the plasterboard with kingspan attached to it (i think as external wall is pure concrete doesn't sound if there is external insulation (styrofoam/expanded polystyrene).
Patio door it is draughty thats why i will have them change in the matter of fact I will have them changed tomorrow for triple glazed 0.7UV they are big doors 8.4m x 2.4m and thats brings me to another question.
What the fitters should do/install between frame and the wall while installing the door to avoid cold bridge? so then i can ask them in advance if they gonna do that so i will make sure its done properly because once done it will be hard to fix the problem of cold bridge
that you for helping out

chicobonito

I forgot to ask is elimination of the cold bridge equal air-tightness?as i want bring up the house to higher standard and because I have so many windows and doors having them air- tight will be definitely a step forward.
Should I mention as well above patio there is a steel beam to which the door are attached is that possible cold bridge too? should they put some sort of insulation between like kingpin cavity closer?

BryanF

Elimination of cold bridges is achieved with continuous insulation at a thickness that keeps the due point to outer face of the insulation.

Elimination of air-leakage is achieved with tape, membrane & sealant. Air-leakage should be stopped at the vapour barrier which is always on the warm side of the insulation.

It's to late to be trying to achieve the above when the Windows/doors are on site. On s commercial job, These details should be on paper and agreed as part of the fabrication drawing approval process. On a domestic job best of luck getting a window company to even give you an accurate u-value, your better off getting an arch to do the detail drawing.