Large glass sided extension - glass suppliers?
Discussion
Obviously doing my own research but interetsed in real life reviews if someone has done something similar.
We are addding an extension to an old property, its in a conservation area and the planners prefer extensions to be obviously modern and not mimic the original house, which TBH suits us
Will be 3 large panes of glass on one side (2 sliding into the 3rd) and two similar panes on the other (1 sliding into other), meeting in a frameless corner.
Looks like this:
First quote from Maxilight was £30k before haggling so looking for other options / recommendations
We are addding an extension to an old property, its in a conservation area and the planners prefer extensions to be obviously modern and not mimic the original house, which TBH suits us
Will be 3 large panes of glass on one side (2 sliding into the 3rd) and two similar panes on the other (1 sliding into other), meeting in a frameless corner.
Looks like this:
First quote from Maxilight was £30k before haggling so looking for other options / recommendations
Equus said:
That's not actually an unreasonable figure.
But before you go that far, have you considered how you're going to make that amount of gazed area work with the Building Regulations?
Have you also considered how you're going to make that frameless corner stand up?
Neither will be easy.
Yes there are internal pillars and I have full structural engineering calcsBut before you go that far, have you considered how you're going to make that amount of gazed area work with the Building Regulations?
Have you also considered how you're going to make that frameless corner stand up?
Neither will be easy.
Equus said:
And the heat loss?
Not sure what you mean, from building control perspective or my heating bills? I imagine 1,000s of houses have these types of design in UK.From the quote if you are really interested:
"Our standard double-glazed units are toughened, hermetically sealed, argon gas filled units with a layer of soft coat glass that greatly increases the thermal insulation and provides a u Value of 1.1W/m²K."
Adam. said:
Not sure what you mean, from building control perspective or my heating bills?
From a Building Regulations perspective. Your heating bills are your problem. 
The normal basic limit on glazed area is 25% of your floor area (plus the area of any existing windows or doors you're losing).
Beyond that, you have to demonstrate how you're going to compensate for the additional heat loss, and a U-value of 1.1 means that the glass is losing approximately 4 times the amount of heat per unit area than the worst allowable specification for a wall (0.28 for an extension, at present)
Adam. said:
I imagine 1,000s of houses have these types of design in UK.
They do. I've designed a few of them myself, which is how come I know that the measures required to compensate for the additional heat loss and manage the solar gain are not as straightforward as drawing a pretty picture on SketchUp.I am also aware that a new generation of the Building Regulations is on its way (you'll need to get the B.Regs submitted before June next year) which will make things substantially more difficult than they are already, and will also introduce rules on assessing for overheating through solar gain in summer.
Equus said:
The normal basic limit on glazed area is 25% of your floor area (plus the area of any existing windows or doors you're losing).
25% of the extension or of the whole ground floor?Why do you have to add on areas of poor insulating glass being removed? Doesn’t that double count the impact of the changes ?
Adam. said:
25% of the extension or of the whole ground floor?
Why do you have to add on areas of poor insulating glass being removed? Doesn’t that double count the impact of the changes ?
Of the extension.Why do you have to add on areas of poor insulating glass being removed? Doesn’t that double count the impact of the changes ?
And no, adding the area of the glazing being removed increases your area allowance, so is to your benefit.
To be clear: you calculate the floor area of the extension. Divide that by four (25%), then add the area of any glazing being removed. The resultant figure is your glazed area allowance for the extension.
That's the 'basic' method. There are a couple of more sophisticated methodologies that allow you further increases in glazed area under certain circumstances, but the point is that you need to have done these calculations to make sure you can make the design comply (it is not guaranteed; neither is lack of overheating due to solar gain in summer), before you splash £30K on fancy frameless glazing.
These guys did our conservatory:
https://lorkinscontractsltd.co.uk/
And I’d absolutely recommend them.
Some experiences. We were able to ignore building regs because we have doors between the conservatory and the house. Doors that are held on with screws and can be removed if needed....
- When they say “do you want the clever glass that attempts to control solar gain”, say yes.
- When they say “ do you want auto opening roof vents to control the temperature”, say yes.
With these two options ticked, our south facing sun trap is habitable all summer, and with the roof vents open, actively pulls air through the house on a hot day.
Our panels are double glazed with very thick glass for safety - you can walk on it quite happily. It seems to be as effective as anywhere else in the house in terms of thermal efficiency in the winter, and as soon as there is a shred of winter sun, it climbs rapidly to about 22C. We’ve recently had it at 38C (vents closed) warming the rest of the house when the outside temperature was about 0 C.
Decent and big bits of glass ARE expensive. You really want a reputable company behind it - one of the big panels in the ceiling “blew” this winter and fogged up. It’s being replaced this Friday, under warranty, which I recall is 10 years from the manufacturer.
https://lorkinscontractsltd.co.uk/
And I’d absolutely recommend them.
Some experiences. We were able to ignore building regs because we have doors between the conservatory and the house. Doors that are held on with screws and can be removed if needed....
- When they say “do you want the clever glass that attempts to control solar gain”, say yes.
- When they say “ do you want auto opening roof vents to control the temperature”, say yes.
With these two options ticked, our south facing sun trap is habitable all summer, and with the roof vents open, actively pulls air through the house on a hot day.
Our panels are double glazed with very thick glass for safety - you can walk on it quite happily. It seems to be as effective as anywhere else in the house in terms of thermal efficiency in the winter, and as soon as there is a shred of winter sun, it climbs rapidly to about 22C. We’ve recently had it at 38C (vents closed) warming the rest of the house when the outside temperature was about 0 C.
Decent and big bits of glass ARE expensive. You really want a reputable company behind it - one of the big panels in the ceiling “blew” this winter and fogged up. It’s being replaced this Friday, under warranty, which I recall is 10 years from the manufacturer.
rxe said:
We were able to ignore building regs because we have doors between the conservatory and the house.
This approach (aside from being unlawful, which is a matter for your own conscience) only works where the structure meets the Building Regs definition of a 'conservatory'. Apart from the thermal separation from the main dwelling already mentioned, this also includes a requirement that >75% of the roof area is glazed, which does not appear to be the case for the OP's design.Adam. said:
Forgot to mention we are also renovated the main property including new windows, and insulated plasterboard to 415sq/m external facing interior walls, plus blocking off some widows so I think we can offset those gains
You can, but only (I believe - our resident BCO's will doubtless be able to confirm) to the degree that your replacements exceed the minimum requirements - remember that you are obliged to meet certain minimum requirements when fitting replacement windows or renovating thermal elements anyway.Equus said:
Adam. said:
Forgot to mention we are also renovated the main property including new windows, and insulated plasterboard to 415sq/m external facing interior walls, plus blocking off some widows so I think we can offset those gains
You can, but only (I believe - our resident BCO's will doubtless be able to confirm) to the degree that your replacements exceed the minimum requirements - remember that you are obliged to meet certain minimum requirements when fitting replacement windows or renovating thermal elements anyway.I planned something similar on my house, but with even more glass 
Architect drew up a very fancy looking glass box which I thought looked the b
ks.
Was gently talked out of it by a very experienced builder who I have since worked with on further projects. His advice - "it's glass, no matter what they tell you it will be cold in winter and too hot in Summer'. We went for huge sliding glass doors, and a well insulated wall and roof with lantern instead. It's all been great but the glass is very noticeably the coldest point in the room in Winter. The bigger the panes the bigger the pain it seems...at least when it comes to drafts and heat.
If the back of your house is sheltered from prevaling winds and isn't south facing then you might be ok, but I'd definitely think long and hard about the liveability of a design like yours before committing.
Architect drew up a very fancy looking glass box which I thought looked the bks.Was gently talked out of it by a very experienced builder who I have since worked with on further projects. His advice - "it's glass, no matter what they tell you it will be cold in winter and too hot in Summer'. We went for huge sliding glass doors, and a well insulated wall and roof with lantern instead. It's all been great but the glass is very noticeably the coldest point in the room in Winter. The bigger the panes the bigger the pain it seems...at least when it comes to drafts and heat.
If the back of your house is sheltered from prevaling winds and isn't south facing then you might be ok, but I'd definitely think long and hard about the liveability of a design like yours before committing.
dimots said:
Was gently talked out of it by a very experienced builder who I have since worked with on further projects. His advice - "it's glass, no matter what they tell you it will be cold in winter and too hot in Summer'.
Your builder was right, and therein lies the problem: glass boxes may very well look the b
ks, but there's a damned good reason that the Regs. don't favour them.Things are going to be even tougher from next year, when both the heat loss requirements are toughened up, and a new requirement to manage overheating through solar gain is being introduced.
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