Convert single to double glazing?

[gregmcateer]

Hi,

We are getting an extension planned for back of house and want to keep original windows on side, but they are single glazed.

One opening top light, rest fixed. I thought about glazing into the recess on the inside, but this would prevent opener.

Is there a satisfactory way of upgrading to double glazing? I thought maybe use the router to deepen the glass recess, or is that pie in the sky? The frame is 48mm thick in total and I am not really sure thickness of a double glazing unit.

Any ideas gratefully appreciated.

Greg

 

[Chrispy]

Hi Greg
Haven't seen them around for a while but you could get rebated sealed glazing units made, where one of the glass sheets was larger than the other, the bigger one fits where the existing glass is and the smaller over laps the glazing bead. it can look a bit strange but may solve your problem.

 

[9fingers]

I've had stepped units in some of my windows for years. At the time, 1982, building an extension on a tight budget, it was cheaper to buy (then) traditional single glazing frames and stepped units. Fitted in with a deeper putty bead, the foil joint is not seen.
I had to replace one a couple of years back due to condensation/leakage and had no trouble getting a new one made by a local glazier.

Bob

 

[Phil Pascoe]

I think the minimum d g unit is 12mm - whether you can get them now with such a small gap, I don't know.

 

[Teckel]

Smallest d g unit is 10mm. I've used these for converting sliding sash windows from single to d g. This was a couple of years ago so maybe you can get thinner units now.

 

[Steve Maskery]

My BIL did the routing-the-frame-a-bit-deeper malarkey. I thought he was bonkers, but actually it worked out looking OK.

I think if I really wanted to keep the existing frames, I'd simply install a new frame on the inside, with casements that open inwards like on the continent.

S

 

[gregmcateer]

Thanks for the tips, gents.
(and sorry for the delay in thanking - I seemed to have lost this thread somewhere!)
Greg

 

[Dibs-h]

Fitted in with a deeper putty bead, ....

My understanding is that's not how to do it - unless it's butyl putty. The butyl tape is a pain and no doubt the butyl putty is worse to handle. LOL

I had to replace one a couple of years back due to condensation/leakage
Bob

Might be due to the putty affecting the black stuff.

Dibs

 

[Bradshaw Joinery]

i have just done this using 4-6-4 units on a 44mm sash.

i rebated out to 14x28 and used a 12mm bead set in with soveriegn silacryl (an acrylic sealant) then used vhb tape and bonded on timber sections with matching mould to make the gb. customer couldnt tell the difference apart from the spacer bar edge, and the fact it was newer....

 

[Crooked Tree]

Once upon a time (before sealed units and plastic windows) you could buy kits to turn single glazing into double by attaching a sheets of glass in a white painted metal frame to the inside of the winwow frame. It opened inwards on plastic hinges and sealed shut against a gasket using sliding catches. A separate piece was used for the little opening bit at the top, with a stay to hold it open on the inside whilst the outside bit was open.

Perhaps you could source/make something like that? It attached to the window frame simply using the screws of the hinges, and appeared to be a lot more effective thermally and accoustically than the wooden sealed units which were installed later in the same house (presumably because of the larger gap between the 2 panes of glass).

 

[andyacg]

i used to make sealed units and the smallest you can make is 4/4/4 or 12mm over all. the outer pane sits in the usual rebate and the alu spacer with hotmelt seal and inner pane sit inside on the sash. always found it a valid method if a little labour intensive. usually means picture framing inside with wooden bead as well as out. avoid using a silicone sealant with the black hot melt as the cheaper stuff doesnt like silicone and results in unit failure.

 

[gregmcateer]

Thanks again for all your replies.
Seems there are more decisions to be made than there are windows!
I may mock up something first and see what SWMBO reckons to the look.
Cheers
Greg