Secondary glazing pondering

[AndyT]

Our hall has a couple of quite nice Victorian stained glass windows. To help keep things a bit warmer, I'm thinking about putting a second sheet of glass in front, which leads to a few questions for the collective wisdom and experience. This is the bigger one:

The existing window is held behind a narrow strip of wood which is fairly flat

I'm thinking that if I first make sure that the current wood surround is properly planar, I could put glazing tape all round, lift a piece of glass into place so it sticks, and finish off with a thin strip of wood all round, planed to an ovolo profile, fixed onto the surrounding wall.

Questions include:

Would this work?
What sort of tape should I use?
What is the ideal gap? (Do I need to add some wood to make it bigger?)
Do I need toughened glass?

I'm assuming I will need to fix any little gaps in the stained glass window's putty, and paint the woodwork one last time, but if it deteriorates after a few years will I wish I had fixed the extra glass to a removable frame, or just surrounded it with non-adhesive draught proofing tape?

There is a second window above the door, in a timber frame.

 

[Myfordman]

A better approach might be to make a shallow frame out of U section timber and use poly carbonate sheet which is much lighter than glass.
The resulting frame can be clipped in place with some home made turn buckles. If a better seal is needed then a little self adhesive draught strip can be fitted to the backside of the secondary frame.
You can take the frames down for cleaning and in the spring pack them away until the next winter.

hth

 

[MMUK]

Another option would be to have your existing pane of leaded glass fitted into a triple glazed unit (it will mean having a temporary sheet of glass for a week or so though) and have a new uPVC frame

 

[Racers]

+1 for the triple glazed, but in a hardwood frame.

Nice window BTW

Pete

 

[Jacob]

Yes to secondary glazing* - but removable so you could take it off in summer, and any time, for cleaning/maintenance etc The cost benefits wouldn't amount to much though.

* outside perhaps? so you don't spoil the best view of the leaded glass and have better protection on the weather side..

 

[AndyT]

Hmm...thanks so far but I really don't intend to routinely remove these as the windows are quite large and I don't have anywhere to store the glass. What works for sealing? Is glazing tape the answer or should I use silicone?

 

[MMUK]

I'd use foam double sided tape, it's easier to remove afterwards.

 

[AndyT]

I'd use foam double sided tape, it's easier to remove afterwards.

Do you mean ordinary diy stuff, not a specific glazing tape?

 

[MMUK]

I'd use proper glazing d/s tape. It comes in all thicknesses from 1mm to 6mm and 10mm. It'll help take out any unevenness in the timber surface. IIRC, a roll of 3mm tape costs me about £4 from Eurocell. Oh, it comes in black or white


Eurocell Bristol - Unit 2, Eldon Way Trading Estate, Eldon Way, Bristol, Gloucestershire BS4 3QQ
0117 971 3371

 

[billybuntus]

Whatever you end up doing, don't use plastic. It'll mark in seconds and annoy you every time you admire your nice panel behind it.

I'd personally drop the panel into a double glazed unit.

 

[RogerS]

Whichever route you go down, just make 100% sure your seal is good. 'Cos any warm air from inside the house will find its way in and condense on the cold outer pane eventually.

when/when not to use toughened, there are regs for windows per se but not sure re secondary glazing. Personally given that it is deep inside an alcove, I wouldn't bother.

Surrounding wood doesn't need to be planar as glass will flex enough and it won;t be that far out. Smooth/smoothish ...most definitely...no little nooks and crannies.

 

[MMUK]

You only need toughened glass if the bottom of the glass is less than 800mm from the floor or within 300mm of a door.

 

[thick_mike]

I put secondary glazing in my old house (ages ago) using some magnetic tape. Put some steel tape on the frame, then the magnetic tape on the glazing (I used Perspex). It worked well and meant I could remove the glazing easily to clean. It made the rooms warmer and helped eliminate draughts.

 

[rafezetter]

+1 for the triple glazed, but in a hardwood frame.

Nice window BTW

Pete

I might be able to help you with this.. I work for a company that can supply double glazed sealed units made to any size, and I'm allowed to get it for a price less than normal - essentially cost +5%.

We also do 2mm or 4mm polycarbonate sheeting that you could do as single or homemade double glazing, we can also get various forms of foam tapes including something akin to the foam divider in the double glazed units (we specify foam as it never develops leaks, it's 1 continuous strip, well sealed at the start/end.).

I would also go the hardwood route, maybe making the the unit frame so that it's further back from the window, as secondary glazing works better with a larger air break in between.

I'd also echo the removable idea as doing it might have unexpected side effects like condensation appearing on the inside of the leaded light window that might need to be dealt with.

This is exactly the kind of setup I have suggested to a friend who has a house in the Brecon Beacons; a rebated frame with rubber seal strip, double glazed unit and a retaining frame on the front, screwed down.

We also sell the magnetic tape as suggested elsewhere.

Drop me a PM with details of window size etc and I can get you a price for a unit which would be at cost +5% (so the company gets a token fee for the books, with no profit in it for me).

 

[pebbles]

Been reading with interest and pondering... would it be possible to side-hinge the new panel still giving a draughtproof fit, but making it easier to clear any potential condensation, but also make it unnecessary to have to remove entirely for storage. Might not be practical but...

 

[MickCheese]

I cannot see how you will keep the void free of any vapour so I think a fixed pane will be a nightmare.

 

[AndyT]

Thanks everyone for the discussion and suggestions which are really helpful. The difficulties that bother me are that I need to make something that is close fitting but removable but there is very little framing to the window - only about half an inch, and of course nothing is straight or square.

I'm not keen on removing the window but I think a combination of magnetic tape and a separate wooden trim (scribed to the walls) could work.

More later!

 

[rafezetter]

Been reading with interest and pondering... would it be possible to side-hinge the new panel still giving a draughtproof fit, but making it easier to clear any potential condensation, but also make it unnecessary to have to remove entirely for storage. Might not be practical but...

Yes of course, you are only limited to the depth of reveal you have that the window sits in so a frame scribed to the walls / header / sill with a good rubber or silicone strip seal would be ample as long as there is enough pressure exerted from the closing system on each side bearer; whether it be screws (if opened seldom), slidebolts, or a latch.

A container of silica gel crystals sat there should help keep the condensation down - or depending on the width of the frame you might get all fancy and be able to incorporate hidden sections (maybe routed out) on the back (inside) of the frame that has a bunch of those small packets in them, so you don't even have to see the crystals.

 

[rafezetter]

Thanks everyone for the discussion and suggestions which are really helpful. The difficulties that bother me are that I need to make something that is close fitting but removable but there is very little framing to the window - only about half an inch, and of course nothing is straight or square.

I'm not keen on removing the window but I think a combination of magnetic tape and a separate wooden trim (scribed to the walls) could work.

More later!

From the picture it looks as though you have a good 300mm depth of window reveal to work with, and you might want to consider bringing, - if you went down that route - the frame to the very edge of the front, almost as though you are
doing a deliberate preservation (which you are) of the window in the same way as is sometimes seen in buildings that have been turned into a museum, where you get those glassed sections with frames in front of say a wall where the substrate has been exposed - effectively turning your leaded light into a cabinet display piece, and the further the frame is away from the window, the less intrusive it will look.

You could even use that space to place a treasured memento to add to the "it's a display cabinet - not a bold but well disguised secondary glazing feature" effect.

 

[AndyT]

Well, thanks to the good advice given, and the generous help of Rafezetter, the job is half way there.

Having settled on plastic sheeting with magnetic tape, so that the secondary glazing is removable and easier to fix than big heavy sheets of glass, I accepted Rafezetter's kind offer to source the necessary bits through his work, and collected the plastic, accurately cut to size, plus the tapes.

The window above the door was the easiest one. The existing stained glass unit was held in with some rough old bits of moulding:

which easily came off

I needed something square to separate the old window from the new, so planed up some wood to suit. To seal it against the glass I used strips of white rubber draught excluder which are hidden behind the wood.

A steel strip sticks to this, and a magnetic strip sticks to the plastic. Together they hold the nice clear sheeting in place

but the tape is visible and needs covering up.

This, of course, was a nice excuse to choose a moulding plane and make some new trim:

and here it is, in painted and in place. The trim is just wedged in by the mitres so it can be removed if needed for cleaning etc.

I now just need to finish the other side, which like everything else in this house needs careful scribing and straightening first.

Thanks again for all your help, and especially to Rafezetter.