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Problems with glazing fitted into green oak frame


Robert Clark

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Hi Guys

 

Our builder appears to have dropped the ball when building our green oak framed extension.

 

Long story short.. the architect specified triple glazing, however I suspect that the builder ordered the frame to take double glazing. By the time this mistake was noticed the frame was built. Sadly the specifications didn’t mention the thickness of the sealed units, only that they should meet building regs and be better than U 1.6

 

The builder has installed 24mm thick triple glazed units, which look very thin compared with other triple glazing we have in the house. I know that the units have low E glass, however I can’t tell if they are gas filled.

 

I’ve asked the builder to provide evidence of the U value, but so far he has failed to do so.

 

To add to the problem, he fitted the sealed units into simple oak frames which are tightly fitted into the green oak frame. Over time the oak has moved and there are now gaps around the window frames which let in draughts and rain.

 

Any idea how I can find out what the U value of the sealed units might be?


If I can prove that the sealed units (and their frames) are not fit for purpose then I can reject them 

 

 

 

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Edited by Robert Clark
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When I was reading various window spec documents there seemed to be an optimal spacing for using argon and a different optimal spacing for uses krypton. I seem to remember that a DGU with 16mm gap would outperform a TGU if the gaps weren’t large enough, sorry can’t remember the actual measurement. It would not surprise me if a 24mm DGU outperform a 24mm TGU, the gaps are less than 4mm. *Edit sorry bad maths of course it is 6mm

 

Here is an FAQ that illustrates this point. 

 

https://www.regencyglass.co.uk/faq-2/triple-glazing-v-double-glazing/

 

Also you get improved sound insulation if the panes are different thicknesses. 

Edited by Nick Laslett
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2 minutes ago, Nick Laslett said:

When I was reading various window spec documents there seemed to be an optimal spacing for using argon and a different optimal spacing for uses krypton. I seem to remember that a DGU with 16mm gap would outperform a TGU if the gaps weren’t large enough, sorry can’t remember the actual measurement. It would not surprise me if a 24mm DGU outperform a 24mm TGU, the gaps are less than 4mm.


I should have mentioned in my post that our sealed units have 6mm spacer bars 

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These guys list a lot of IGU with different u-values. 
 

https://www.regencyglass.co.uk/sealed-unit-types/thermal-performance/u-values-library/

 

They don’t do a 24mm TGU. The 28mm unit has a u-value of 1.0. 
 

We used illbruck Trio compriband tape for our windows install. They do a tape specific for timber frame that can accommodate differential movement.  
 

https://www.illbruck.com/en_GB/product/tp450-compriband-timber-max/

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3 hours ago, Robert Clark said:

Any idea how I can find out what the U value of the sealed units might be?

 

If you are not sure of the spec, then you will need to go to the manufacturer.

 

However,

 

3 hours ago, Robert Clark said:

Sadly the specifications didn’t mention the thickness of the sealed units, only that they should meet building regs and be better than U 1.6

 

Is it not the whole window value that needs to be under U 1.6, not just the glass?

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17 minutes ago, IanR said:

 

If you are not sure of the spec, then you will need to go to the manufacturer.

 

However,

 

 

Is it not the whole window value that needs to be under U 1.6, not just the glass?


Sadly I don’t know who manufactured the sealed units and the builder is not providing any info about them.

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4 minutes ago, Robert Clark said:

Sadly I don’t know who manufactured the sealed units and the builder is not providing any info about them.

 

Surely he will have to for Building Control

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4/6/4/6/4 glazing unit. I’m going out on a limb here and saying he hasn’t ordered with Krypton filling.


I’m also assuming Planitherm One as coating but unlikely and needs specs to be sure. Which he will need to provide.

 

1.2W/m2K argon filled 90%

 

3 hours ago, IanR said:

Is it not the whole window value that needs to be under U 1.6, not just the glass?


Yes but here there is no window frame, it is glass in the building framework and would pass.

 

6 hours ago, Nick Laslett said:

there seemed to be an optimal spacing for using argon and a different optimal spacing for uses krypton.


Optimal for Argon and Krypton is 18mm, larger gaps create convection.

 

Current building regs is 1.6W/m2K for windows, changing in June to 1.4W/m/K

 

 

Edited by craig
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1 minute ago, craig said:

Yes but here there is no window frame, it is glass in the building framework and would pass.

 

It didn't look like a structural element to me, looks like a frame within the fenestration. Can you get away with calling the glazing frameless in the scenario?

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3 minutes ago, IanR said:

 

It didn't look like a structural element to me, looks like a frame within the fenestration. Can you get away with calling the glazing frameless in the scenario?


You’re right my bad for not zooming in on the phone 🤦‍♂️
 

If it was straight into the fabric yes, but not in this scenario (clearly framed and beaded now I have zoomed in).

 

Might even be possible that joiner has made these frames. Beading looks like edge bead?

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4 hours ago, ADLIan said:

That table and link are 2021 version of Part L which does not come into force until 15 June 2022. From memory current  standard for windows is U=1.6

 

For timber windows, the current U value requirement (1.6) is carried forward into the new regs until 14.06.2023, so makes no difference if you read the old or new regs (for timber windows only)

Edited by IanR
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