New to triple glazing

[joeboy]

First enquiry post. We are new to triple glazing and are surprised at the complexity of choice.

 

We have been on a renewable energy journey for a number of years with much gap sealing and a lot of insulation added to the home. In no way though would I claim any sort of air tightness value but it is significantly better than we started with. We are looking to replace our 2g (which was the cheap stuff we could afford then) with 3g and would like any advice on how high to aim. Bearing in mind it's a mid 80's Barrett bungalow. My understanding is that all the windows should be taped internally and gaps filled externally with low expansion foam to reduce thermal bridging and airflow? Anything else to look out for or request during installation? Advice much appreciated. Windows are to be upvc 3g argon filled with toughened glass. Quote process begins this afternoon. Thanks.

Edited September 16 by joeboy

[JohnMo]

There are 3G and there are 3G. First you need to compare the U_w values. Frames make a huge difference in window performance. If the company will not give you that value find another. The value they may quote is U_g this us only the glazing element.

 

Tell tail of good uPVC is look at a frame cross section and it should have many small air pockets in the frame profile. Bad ones have one or two.

 

The installer makes a big difference, most can be or are poor. Ask non leading questions to dig out of the company, details of they install the windows. They really need to have every gap filled with foam to get rid of cold bridging.

 

New thread for you to start is ventilation, making house airtight is good, but not addressing the ventilation strategy an omission, that leads to issues. Ventilation strategy will also feed in to the final design of the windows.

Edited September 16 by JohnMo

[jack]

3 hours ago, joeboy said:

We have been on a renewable energy journey for a number of years with much gap sealing and a lot of insulation added to the home. In no way though would I claim any sort of air tightness value but it is significantly better than we started with. We are looking to replace our 2g (which was the cheap stuff we could afford then) with 3g and would like any advice on how high to aim. Bearing in mind it's a mid 80's Barrett bungalow. My understanding is that all the windows should be taped internally and gaps filled externally with low expansion foam to reduce thermal bridging and airflow?

 

Great to hear you've done the boring but effective stuff first.

 

When it comes to window installation (3G or otherwise) you really want to make sure the installers know what they're doing. There are ample horror stories on BuildHub (+ Grand Designs etc) about installers cocking things up. I had plenty of issues - the window installation is one of the two biggest cock-ups I had on our build.

 

If possible, consider having have the supplier arrange the installation, even if it's a bit more expensive. What you don't want is something happening and the supplier blaming the installer and vice versa. If one party is doing both, you completely skip that argument if something goes wrong.

 

I'm sure you're on it, but anything you can do to improve insulation around the frame will help. If the gaps are big, that might include putting in some rigid or rockwool insulation to completely fill the gap before sealing inside and out.

 

You can also use compriband or similar products to provide the outermost seal.

 

The only other thing that jumps to mind is to think about how your windows are mounted. Our installer used galvanised straps, but bent them in such a way that it made plasterboarding very difficult.

 

Good luck.

[joeboy]

Thank you both. Pertinent points emerge from the mist of my confusion.

 

Ug good 

Uw better

Frame spec matters as does the x sectional build to maximise air pockets. (The x seciton I have seen was a complex beastie with lots going on.

How are the windows mounted?

How are the windows internally and externally sealed?

Hinges matter as does the size of opener, less is better but escape path is critical?

Window builder through to installer is the preferred route to avoid any "he said, she said". (That would be horrible).

Is there a spec to look for in Uw & Ug for thermal efficiency? No point my paying for 0.5 Uw if the house can't keep up?

 

Wondering on opinions/experience on South facing v's North? Does it affect the 3g unit build? Is there a way to let more heat through on South side and block more exiting on the North in the glazing unit build?

 

Ventilation is critical. We have not fitted MHVR but do run dehumidifiers in Winter and we do ventilate. No mould or health issues.

 

Thank you very much for your replies, a hit list begins to form!

Edited September 16 by joeboy

[JohnMo]

1 hour ago, joeboy said:

Ug good 

No, it tells you nothing about the window unit performance. Agon triple glazed units all have the same U_g number.

 

1 hour ago, joeboy said:

but do run dehumidifiers in Winter

So you need a proper ventilation strategy. Can I suggest the following 

 

dMEV. You need a fan in each wet room, and no trickle vents in those rooms. All dry rooms have trickle vents. The trickle vents need to be self modulating and or reactive to humidity. dMEV fans run at a very low rate call the time and the ones I am going to suggest are silent and automatically adjust speed when sensing a humidity rise and go back to a slow speed when cleared. The only need power to them.

 

dMEV fans - use Greenwood cv2gip.

 

Self modulating trickle vents, have a search on here via Google. The window people may just look back at you blankly.

 

As your NE Scotland give Wood Kraft in Elgin a call also, they make wooden windows. Did ours.

 

Another alternative to 3G is 2G krypton filled. That will give you U_w of 1.0 with the right frame.

[joeboy]

1 hour ago, JohnMo said:

No, it tells you nothing about the window unit performance. Agon triple glazed units all have the same U_g number.

 

So you need a proper ventilation strategy. Can I suggest the following 

 

dMEV. You need a fan in each wet room, and no trickle vents in those rooms. All dry rooms have trickle vents. The trickle vents need to be self modulating and or reactive to humidity. dMEV fans run at a very low rate call the time and the ones I am going to suggest are silent and automatically adjust speed when sensing a humidity rise and go back to a slow speed when cleared. The only need power to them.

 

dMEV fans - use Greenwood cv2gip.

 

Self modulating trickle vents, have a search on here via Google. The window people may just look back at you blankly.

 

As your NE Scotland give Wood Kraft in Elgin a call also, they make wooden windows. Did ours.

 

Another alternative to 3G is 2G krypton filled. That will give you U_w of 1.0 with the right frame.

That is a very good point on the dehumidifiers. I didn't know there were humidity sensing trickle vents and fans. That's a bit of an eye opener. A good one though. Did you run without these units at all and see a difference when added? You are the third person in two days to say about the thermal efficiency of high thermal efficiency 2g. Food for thought. Thank you.

Edited September 16 by joeboy

[JohnMo]

3 minutes ago, joeboy said:

Did you run without these units at all and see a difference when added? You are the third person in two days to say about the thermal efficiency of high thermal efficiency 2g. Food for thought

I use a Greenwood fan in our heated summer house. It's the second unit we tried the first one fitted (another make) was noisy. Humidity tracks very closely what the main house does with MVHR. 

 

Our house is mostly 3G except some glazed doors, which are Krypton 2G. Don't let them pass 1.4 U_w as high performance, they just comply with minimum Scottish building regs.

 

 

[JohnMo]

https://forum.buildhub.org.uk/topic/34444-humidity-activated-trickle-vents/

[RobLe]

Most DG installers used to use pilkington k, a ‘hard coat’ metal layer on an inner glass face, the DG would typically be Ug=1.4W/m2/K. In contrast Planitherm 1 by st gobain is Ug = 1, a significant improvement.  Pilkington offer a similar soft coat too; it used to be hard to find (I don’t know now).  All the above were with ‘typical’ 4/16/4 thickness DG units.  Obviously 3G is better, but again the actual glass coating makes a huge difference - I didn’t find the lower u value glass cost any more, all else being equal.

[joeboy]

1 hour ago, JohnMo said:

I use a Greenwood fan in our heated summer house. It's the second unit we tried the first one fitted (another make) was noisy. Humidity tracks very closely what the main house does with MVHR. 

 

Our house is mostly 3G except some glazed doors, which are Krypton 2G. Don't let them pass 1.4 U_w as high performance, they just comply with minimum Scottish building regs.

 

 

Thanks, so far we've been.offered 1.2u falling to 0.6u spec depending. I think Ug but I've learned now to ask for Uw. It's only the first quote in so far. I have about 6 lines in the water at the moment. Interested to see who is most forthcoming with detail in reply without request. It's been a weird few days dealing with the glazing folk. Some good, some bad. Tbh, they don't seem to have changed much since the 80's. Slightly better tech patter. 

 

I do like the idea of humidity reactive gear. Could have a trickle vent in kitchen, then humidstat fan in each of ensuite & main bathroom. Thanks again for that

Edited September 16 by joeboy

[joeboy]

Hi all,

I have a decent quote at a good Uw value with a few more quotes to come in. The installers are willing to work with me so that I can do remedial works as they work through the property then circle back and complete internal finish. With this in mind I have noted from the forum Illbruck FM310 low expansion foam for external sealing of window and Siga Corvum 12/48 tape for the sealing off of internal frame edge pre finish.

 

The house is not airtight to any standard beyond my own works across the years but i'd like to maximise the thermal impact + of retro fitting these 3g units and zero 90 frames. Have any of you did any works to thermally isolate the frames externally from the building opening (beyond low expansion foam)? Is it worth specifying a specific UPVC cill or isolating it in some way? Any particular brand of thermal reveal for the internal finish?

 

Any advice much appreciated, apologies if I mismatch terms.

[MikeSharp01]

I would look to see if you can use the Illbruck Compriband tapes to seal the outside then inject the foam from the inside behind the compriband this is the way ours are fitted.

 

[joeboy]

58 minutes ago, MikeSharp01 said:

Thanks MIke, Did you by any chance have a look with a thermal imaging camera once the work was complete? I had a look today with my cheap Flir unit. Quite the dark lines around all internal window edges.

 

[Bozza]

If within budget can recommend Rationel 3G from ADW at Sauchen.  

[joeboy]

13 hours ago, Bozza said:

If within budget can recommend Rationel 3G from ADW at Sauchen.  

Thank you, a friend speaks well of them. I have just agreed a contract with another local firm. Thank you though. I am going upvc as I'm at the less maintenance is better end of my life. Wondering what folk use to create a thermal break between the building concrete cill and the upvc cill that the 3g unit and frame will rest on? Thanks