Modern "stained glass" fitted by double glazing companies is simply coloured transparent film and adhesive lead stuck to the inside and outside of one of the panes of glass in a double glazed unit.
Instead of this, you can make a piece of stained glass and have that sealed inside a new unit, keeping the benefits of the double glazing, whilst installing a window that will look better than the modern version.
This can be done with all types of double glazing; uPVC, wood and aluminium, although uPVC is often by far the easiest.
uPVC can be internally or externally beaded. With internal beading, the beading is removed from the inside of the house and, unless the double glazed unit is actually clipped into the frame, is fairly easy to remove.
With external beading, the beading is on the outside of the house, but the unit may have rubber gasket on the inside, which needs removing, or be stuck to the frame with security tape. Security tape is a spongy, double-sided adhesive tape, which will need to be cut with a knife to remove the unit from the frame. This is typically the most difficult type of uPVC unit to remove.
Units in wooden windows may have wooden beads, or be puttied in. Both are normally on the outside of the frame, and putty requires chiseling off. The unit may also be stuck into the frame with sealant.
Aluminium windows usually require the frame to be dismantled in order to remove the unit.
If you aren't that skilled at DIY, you may need to get a specialist to help you with both measuring the window, and fitting the new unit. If looking in the phone book, you want a company that does or specialises in double glazing repair and maintenance. National or local replacement window companies are likely to, if they will actually do the job, be very expensive.
If you do the replacement yourself, you will need a double glazed unit manufacturer to make the new double glazed unit. Again, look in the phone book. If you're using a fitter, they will sort this bit out themselves.
To measure the size of the replacement unit that will be made, you want to measure, on a uPVC window, from channel of bead to channel of bead (see diagram below), to get the width and height, then subtract 10mm from each dimension. This works with both internally and externally beaded windows; just ensure that you are measuring the side the bead is on.
You also need to know the overall thickness of the unit. If you can, measure the thickness with a pair of calipers or similar. uPVC double glazing is usually 20, 24 or 28 mm in thickness, with 20 being found mostly in older units.
You should now have the width and height of the unit, as well as its' overall thickness. Make a note of these.
To get the size of the piece of stained glass you are going to be making, take another 25mm off the width and height. These are the measurements to the edge of the glass, not the edge of the Y-lead. Don't worry if your finished piece is a couple of millimetres out, as there is some flexibility in most uPVC, allowing a unit that is a bit too big to still fit. Units that are too small can be more of a problem.
Once you have finished your piece of stained glass, you need to give it to whoever is going to manufacture the unit, whether a double glazing fitter or manufacturer. Once finished, it will then need fitting.
If fitting yourself, be careful of the edges of the unit. Some double glazed units have tape around them, but not all, and the glass is sharp and can easily slice your hand open.
Double check to see that the unit is the right size before removing the existing unit.
fit the new unit: a glazing mallet, a glazing shovel and some glazing packers. Packers are put inside the frame and the unit is rested on them. This keeps the unit out of the water when it rains. If the unit is installed without packers, the excess moisture will cause it to fail (mist up) much more rapidly. Glazing packers come in a range of sizes. All of these should be available from any supplier that caters to the glazing trade (double glazing or glazing suppliers in the phone book).
Rest the new unit inside the frame to check that it fits, and see how many packers you will need. Put the packers inside the frame.If the frame had security tape, stick that to the frame where the old tape was, and remove the covering where the unit will be stuck to it. Carefully place the unit in the frame - again, if using security tape, ensure you get it right first time - and then replace the beads in the reverse order to the way you removed them. If externally beaded with rubber gasket, now replace the gasket.
You should now have a new, proper, stained glass unit in your toplight.
After fitting your new stained glass unit, it is worthwhile, if you have the space, to keep the old unit as a spare, in case you need to remove the stained toplight for any reason.