New windows - huge cold spots & draughts

[SanMan]

We had new Rehau uPVC windows installed earlier this year. Now that the cold weather is here, I have noticed that some of them feel noticeable cold and draughty around the reveal, not the glass or rubber gaskets themselves. It could also be coming from the outer uPVC frame, I am not sure. Please see attached photo. It almost seems like there is a hollow around the window. Only some windows are affected. How is this possible and can this be recitified, for example by drilling a hole into the plaster of the window reveal and injecting foam? Thanks. 

[Spreadsheetman]

Do you have cavity walls and did you see if there were insulated cavity closers to the sides of the window when they were fitted?
 

I recently had a couple of windows replaced in my 70s chalet and the window reveals were solid block bridging the cavity sides and below. I.e. a big cold bridge. These blocks had to be cut out and insulated closers fitted before fitting the windows.

[SanMan]

Thank you. Yes, they used cavity closers. I watched them do it, but there are lots of windows at our house and they had 4 people working, so I did not see every single step. When they took the old windows out, they disturbed plaster and the edge of the brickwork. I wonder if there are ragged edges. I have a boroscope….I wonder if it is worth drilling a small jolt into the reveal to have a look. 
Also, why would the actual white frame be so cold? 
Thank you. 

[Adsibob]

3 minutes ago, SanMan said:

Also, why would the actual white frame be so cold? 
Thank you. 

Because uPVC windows are not great insulators. Think of a plastic ice tray sitting on your palm of your hand. How long before your palm starts to feel the cold of the ice?

[dpmiller]

35 minutes ago, Adsibob said:

Because uPVC windows are not great insulators. Think of a plastic ice tray sitting on your palm of your hand. How long before your palm starts to feel the cold of the ice?

do you think a uPVC frame is solid plastic?

[Kelvin]

58 minutes ago, Adsibob said:

Because uPVC windows are not great insulators. Think of a plastic ice tray sitting on your palm of your hand. How long before your palm starts to feel the cold of the ice?

Place a bit of insulation on your hand then place the ice try on top which is how the uPVC window is made up. It’s not solid plastic.
 

 

Edited December 10, 2022 by Kelvin

[Adsibob]

5 minutes ago, dpmiller said:

do you think a uPVC frame is solid plastic?

Of course not. There is insulation sandwiched in between. Wood is a better insulator than plastic. Plastic is ok, just not as good as other materials. Also, as uPVC is a cheap material, i wouldn’t be surprised if the windows have used inferior insulation elsewhere in the unit.

[SanMan]

There is no insulation in the uPVC frame. The thermal qualities rely on the hollow plastic channels in the frame. 

[SanMan]

[Radian]

9 minutes ago, SanMan said:

So your's is this DG unit with MDPE thermal breaks. Very good performance across the broken sections I expect but laterally you have UPVC bringing the cold directly in from your bridged reveals. Maybe the frame is a tight fit into the reveal at this point?

[SanMan]

Thank you @Radian. 

 

Yes, I wonder if this is it. A fitting error that cannot be rectified? Is the unit possibly too big for the reveal? Anything I can do? 

[Radian]

1 minute ago, SanMan said:

Thank you @Radian. 

 

Yes, I wonder if this is it. A fitting error that cannot be rectified? Is the unit possibly too big for the reveal? Anything I can do? 

If you don't take steps to remedy it, I would expect this to be a permanent source of condensation leading to mould. You could start by inserting your scope into a diagonally drilled hole a little way from the frame to get you into the junction between window frame and outer leaf of wall. Do it about half way up the bit you marked on the photo BUT MAKE SURE YOU MISS THE FRAME! You could make thigs much worse if you breach the hollow frame!

 

Alternatively, have a good look outside to see if there are signs of the frame being jammed in tight to the reveal. If it turns out to be a tight fit you shoud get your installer to come back and sort it out. If it's stood off with packers it's just down to the state of the reveal which probably means cutting it away and re-boarding to remedy any cold bridging. You could certainly try injecting foam and seeing if it helps first, but how effective it might be would be anybody's guess.

[j_s]

I have serious issues on our double glazed (4-20-4) aluminium window in the ensuite and master bedroom. I also have mvhr so the room has fresh air coming in and doesn't drop too low in temp over night. I'm confident that it's due to them being set too far forward and not on packers. Are your windows set back into the reveal over the cavity and that the closers were 100% sealing the cavity off? If not then cool air will be getting around the frame and cool air hitting those points you show. 

 

My newer aluminium triple glazed windows are set much further back in the reveals on packers and although cool to the touch are doing their job. Reveals are also sealed off from the cavity with closers that are foamed and glued and taped in along with insulation right up to the closer insulation. 

Edited December 10, 2022 by j_s

[Gus Potter]

As the mould / damp bit is at the bottom I would take off the plasterboard on the window ingoe where it is at it's worst. Yes there will be a bit of disruption but it is the best way of getting to the bottom of the problem.. UPvc windows are fine .. it's the fitting of them that 99% of the time causes the problem.

 

Two basic things I would look for and suspect..

 

1/ Window fitters are notorious for not closing and installing the cavity closers properly. They will shove something in for good looks but particularly on a retro fit you often have mortar snotters and wall ties in the way. They are pushed for time so often don't care.

 

2/ You have a cill that should be sealed to the bottom of the window frame so that the water drains out through the front, usually done with a bead of silicon when the cill is fixed to the window before installing. Check to see if there is dampness when you open it up.

 

To make sure get a hose and spray it on the window for 10 -15 minutes and look at the bottom corners.

 

 

 

 

 

 

[saveasteading]

12 hours ago, Adsibob said:

uPVC windows are not great insulators

As opposed to aluminium?

 

[craig]

You’ll actually find that Uf values (uPVC system dependant) are generally thermally better than wooden windows. Especially uPVC systems with 5 / 6 chambers and or insulation within the chambers.

 

Not a lot you can do now other than what @Gus Potter and others have said. You need to open up to see what hasn’t been done and get them to rectify or do it yourself.

[Adsibob]

13 hours ago, saveasteading said:

As opposed to aluminium?

 

I had wood in mind, but it looks like I might be mistaken.

We have thermally broken aluminium 2G windows and a thermally broken stell 2G door. The aluminium windows perform better than the steel door, which is to be expected as the aluminium windows had a higher energy performance rating than the steel door.

[HughF]

Surprise surprise, a window installation company have done a mediocre job....

 

Hack the reveals off, see what's underneath...

[AliG]

That is the coldest area in all the walls in my house.

 

Almost my definition it will be. The walls are insulated with a very low U-value and the triple glazing has a low U-value. The weak spot is the window frames, plus any bodges around them when the windows were installed.

 

So I guess the question is are these areas colder than the should be. I would expect them to be a good few degrees cooler than the glass and walls especially when it is as cold as it has been. My windows have aluclad wooden frames, I think most uPVC frames would be worse.

 

When you say they are "draughty" do you mean that you can actually feel a draught. This would suggest that the windows are not tight in their frames. Or is it just that the area feels colder than the surrounding area.

 

I actually tried the experiment of injecting foam into the reveal on one side of a window to compare to the other side.

 

I just took an IR picture of it and it has made no difference. Both sides are basically the same temperature. The RHS has foam, the LHS does not.

 

The worst points seem to be the corners as you can see.

 

 

[Roger440]

Ive never been all that clear on exactly how one should install a new window.

 

If squirty foam isnt what to fill the gaps with, how is it done?

 

Google isnt telling me any different. Lots of pretty pics of cross sections of the window, but not of the whole deal

[saveasteading]

1 hour ago, Roger440 said:

but not of the whole deal

I think if we were to draw one of the above windows in the context of masonry outer skin, cavity etc, it would show a weakness, a relativd cold bridge bypassing some of the window construction, so it will be colder round the edges.

I think windows are tested in an ideal jig in the laboratory; not in real walls.

[Roger440]

37 minutes ago, saveasteading said:

I think if we were to draw one of the above windows in the context of masonry outer skin, cavity etc, it would show a weakness, a relativd cold bridge bypassing some of the window construction, so it will be colder round the edges.

I think windows are tested in an ideal jig in the laboratory; not in real walls.

 

I agree. So how it it done in something like a passiv house, or something to that standard?

 

[AliG]

The correct way to do it is to tape around the reveal between the frame and the wall to make it airtight. This might be on top of any foam to fill the gap around the frame.

 

You would then probably use insulated plasterboard in the reveal on top of this.

 

The issue is that depending on available space, width of the frames etc this is not possible,

 

Within reason the small cold bridge is not the end of the world. The cold air getting in around the frames and behind the plasterboard is the bigger issue and if you can address anything this is what to look for.

[Gone West]

3 hours ago, AliG said:

My windows have aluclad wooden frames, I think most uPVC frames would be worse.

There is a large variation in types of uPVC window profiles. In my PH I had triple glazed Rehau Geneo frames which were insulated. The standardised figures were

Ug value = 0.5 W/m²K
Uf value = 0.77/0.78 W/m²K
Uw value = 0.67 W/m²K

[saveasteading]

3 minutes ago, Gone West said:

which were insulated

Physically insulated or air cells?