Fitting the systems
1: Polythene film To fit this very basic form of fixed double glazing you will need just a roll of double- sided adhesive tape, a roll of clear polythene, a tape measure and pair of scissors or handyman’s knife. Stick the tape, without removing the backing paper, to the face of the outer window frame all round the perimeter. Measure the size of the opening and cut a piece of polythene to suit. Remove the backing paper from the top piece of tape and attach the edge of the polythene gently to it. Allow the sheeting to hang down. Check that it fits squarely before removing the backing paper from the other three pieces of tape and securing the polythene to it, keeping it stretched taut all the time. Strong, less creasable polythene, classed as semi-rigid, can be fixed in a different way by cutting it to the exact size first, then attaching the sticky tape to it rather than the window frame With the backing paper removed from the top edge only, the sheet is aligned to the head of the window frame, then stuck in place, followed by the other three edges.
2: Non-opening removable panels The most recent version of this form of double glazing uses a P V C extrusion stuck to the window frame, with a second extrusion holding the plastic sheeting in place. The work required involves cutting the PVC extrusion to size and fitting it around the existing frame. Either butt or mitred joints can be made at the corners. The plastic sheeting is then cut to size to fit in the profile. The clip-on extrusion is finally cut to size and snapped into place.
Other variations of this non-opening type of double glazing usually consist of plastic ‘IT channelling fitted around pre-cut panes of glass. The glass, now with protected edges, is secured to the window frame with turn buttons or clips spaced every 300mm (12in) around the perimeter to press the panel firmly against the frame and so exclude draughts. The glass for this type must be cut to size, allowing for the space taken up by the fixing clips on the frame. The panels can be removed and stored elsewhere at the end of the winter season.
Rather stronger non-opening panels can be made using aluminium framing instead ot plastic ‘IT channel, but these are generally a fixed version of hinged panels described next.
3: Hinged panels The most common hinged secondary double glazing systems are constructed using glass with an aluminium extrusion frame. The frame incorporates one channel with a plastic glazing gasket for the glass, a draught-proofing insert of either plastic or nylon fibre bristles which press against the window frame, and a second channel into which hinge fittings, turnbuttons and corner joins are fitted.
Glass of the specified thickness is cut to size Some makes can be fitted with more than one thickness of glass, this being determined by the overall panel size.
A different size of glazing gasket is used for each thickness. Once the glass is cut. the glazing gasket can be fitted to it, and the aluminium extrusions cut to length using a hacksaw. Straight cuts are made since the special corner joins eliminate the need for mitred corners. The panel is then assembled, special care being needed to ensure that the glazing gasket is correctly seated in its channel and that all hinge fittings are properly inserted in the outer edge of the aluminium frame. Hinge posts are then screwed to the window frame and the panel is lifted into place. Turnbuttons are finally fixed round the other three edges of the hinged panel to ensure that the panel is held tightly against the window frame when closed.
4: Sliding panels Made from either aluminium or PVC extrusions, sliding double glazing units are generally quick and easy to assemble and fit. Normally sold in two-part kit form with everything but the glass provided, the biggest problem is often deciding which part belongs where, so the first step is to identify the different sections. One part of the kit will contain all the vertical sections – the frame uprights and glass edging – and the other, the horizontal sections – the top and bottom sliding tracks and more glass edging. The outer frame is fitted to the window reveal. This will usually involve drilling holes into the reveal sides, top and bottom and plugging the holes to take screws. Great care must be taken to ensure that the top double channel (the deeper one) is fitted directly above and in line with the bottom channel.
With the frame secured, the panes of glass can be fitted with their edge profiles, and the panels are then lifted into position in the sliding channels. Provided that you have measured the glass correctly according to the instructions given by the double glazing manufacturer, you should find that the panels slide easily and that all nylon fibre draught excT&ders built into the system align perfectly.