poor quality window install

[Balou]

hello all. We moved into our new build home 3 years ago. It was a single build with a builder we trusted.  There have been substantial problems with the windows that were installed by a local installer who was brought in by the builder. In those 3 years, weve had 6 sealed window units and a bifold door unit fail and have to be replaced. Weve had a 4.5 m bank of balcony doors and windows had to be removed because rain water  had got in around the frame and damaged the ceiling below it(in about 12 places). The frames had also cracked through in two corners. The replacements were fitted, but still draughty. A 4.5m set of bifold doors has had ongoing problems with rain and draughts getting in, despite numerous visits by the installation company and are still a problem (draughts will easily blow a candle out on a windy day). Weve got 3 top hinged ground floor windows that if we open them in the summer on hot sunny days, they warp and we cant shut them again for several hours. We also have several sealed units in a double height staircase window, where the upvc frame has cracked through in 2 corner joints, which im wondering if its structural with the weight of 2 sealed units above it pressing down. On top of that, numerous visits and repairs by the installers where locking mechanisms on the windows have failed (taking months to replace) etc. Ive honestly never come across so many problems with windows before. On top of this, we have a huge amount of air getting past the cavities and wall insulation to the point that air coming from behind a wall mounted stat ( located about 3 feet from the bifolds) will blow a candle out and cause the stat to be permanantly calling for heat. With that in mind, and with all the other quality issues, im wondering if the windows have been fitted without cavity closers being present- Is that possible? Really not sure what our best course of action is now. We havent paid the installers direct as they were brought in by the builder, who's not being particularly helpful. Thinking of getting an independent surveyor to do a report, but not sure where to find one ? Sorry for the long spiel, but its been a long three years. Any suggestions would be appreciated.

[Nickfromwales]

What make are the units?

[craig]

1: Location.

2: Window manufacturer/brand

3: Bought by installer or made by them?

4: photos/videos?

 

Let us know and we can assist if we can.

[Balou]

I believe the units are made by Sternfenster, in Lincoln (although the installer is rather guarded about this for reasons unknown)and bought in by the installer . We are located near Wisbech, Cambs. I’ll sort some photos out tomorrow hopefully. Many thanks. 

[Nickfromwales]

Just now, Balou said:

I believe the units are made by Sternfenster, in Lincoln

Guess who you're ringing tomorrow for a chat about this installation!!

[Mr Punter]

It sounds like a combination of poor fabrication, poor install and poor quality sealed units.  I don't know how the profiles perform.  I think they are Deceuninck.

[Balou]

On 10/12/2025 at 19:35, craig said:

1: Location.

2: Window manufacturer/brand

3: Bought by installer or made by them?

4: photos/videos?

 

Let us know and we can assist if . 
 

I’ve added a few photos of the bifold doors and the stairwell windows. I had tried to add a video of the draughts from the bifold blowing out a candle, but the file is too big. On the staircase windows-The exterior frame corners of the tall windows have cracked on the horizontal bar above the first window and I’m concerned that the frames are structurally not strong enough for the weight of the glass units. 

[Nickfromwales]

16 minutes ago, Balou said:

The crack is very likely to be installer error imho. They have likely screwed through the frame and into the masonry way too close to the corners; the effect of then overtightening these fixings just places huge force of the welded joints, forcing them to pop open.

 

A way to prove (or disprove) this would be to remove the glazed unit and inspect where the fixings have been placed. 

[craig]

26 minutes ago, Nickfromwales said:

49 minutes ago, Balou said:

 

The crack is very likely to be installer error imho.

i would tend to agree, welds don’t just crack, that’s to be opposite forced. Fixings should be 150mm from the corner (horizontally & vertically).

 

26 minutes ago, Nickfromwales said:

emove the glazed unit and inspect where the fixings have been placed

This.

 

It’s the only way to check, otherwise it has to go down as a manufacturing error. I would also suggest they haven’t packed them properly.

 

As for glass, units fail. That’s just an unfortunate aspect but rare for brand new units to fail like this over a short period without other influences occurring (either that or glass manufacturer is just ****e.

 

Sashes that are difficult to close due to expansion, is nearly always down to poor installation, with packers and fixings not being present or just really poorly done.

 

I would suspect that you have zero insulation between the frame and building. Resulting in the said airflow.

 

I have someone in mind, lives in Lincoln but we haven’t spoken in a year or two. I’ve messaged him and will see what I can do. Otherwise I have someone in Henley or I could do an independent report but Lincolns a 6.5hr drive for me.

 

If you have a laser, run it up the glazing beads (where frame meets glass). It should be straight and if not and you see some pinching. It would indicate further inspection of packers/fixings.

Edited 21 hours ago by craig

[Nickfromwales]

31 minutes ago, craig said:

but Lincolns a 6.5hr drive for me.

If you set off at 00:30 you'll be on site for 07:00  

[Gus Potter]

On 10/12/2025 at 17:33, Balou said:

We moved into our new build home 3 years ago.

I'm going to be the devils advocate here and assume that the window installer thinks they are not to blame, they have engaged me to defend them.  First I'm going to put my SE hat on. 

 

With that hat on I want to see if your house is a bit "flexible" and prone to sideways movement. @Balou can you post some full elevation photos. Now if it turns out that your building is flexible then I would, in the installers defense, start asking the SE type questions.. in other words is the building moving sideways as designed by the SE within limits and also vertically (withing limits) and causing out glazing to fail? as the glazing contractor has not accounted for the SE movement in their installation.

 

I can't easily see how the bricks are supported over the bifold doors. Again here if defending the glazing contractor I would want to know about this and cavity tray design.

On 10/12/2025 at 17:33, Balou said:

We moved into our new build home 3 years ago

I would also want to know if you have made later alterations since you moved in, have you done something that could compromise the building performance that has cuased the building to move and over stressed the glazing and this has resulted in the problems manifest. 

 

If you have not done any of the above then the glazing provider seems to be on a sticky wicket!

 

 

58 minutes ago, craig said:

i would tend to agree, welds don’t just crack,

I agree Craig. It could be that the window frames are absolutely fixed to the main frame of the house and as that moves about it's causing overstress in the windows and doors. By the sound of it the workmanship appeares shoddy, not maintaining air tighntess for example.

 

In the round though there are so many issues it apears to me that the product could just be faulty and the installation is poor.