Having used the double glazing film successfully last winter, I ordered some cut to size acrylic sheet last week. It arrived today, which was fortunate, as it was very cold here last night and the windows were covered with condensation this morning.
I had also ordered self adhesive magnetic seal, to attach the acrylic to the frames and started fitting at 5.30 this evening,. The windows are all aproximately 1200x600mm, with flat wooden surrounds, typical of most modern fitouts. I removed the hoppers, although the opening glasses would be self supporting on the frame if I needed to open any. My wife and I cleaned the windows thoroughly, and sealed the drainage holes with sealastic, then sprinkled some silica gel crystals from Wilkinsons into the channels, to absorb any moisture between the frames. We then stuck one half of the self adhesive magnetic seal tape to the outer edges of one of the sheets, making sure there were no gaps. The other half of the tape was then magnetically attached to the stuck tape, again allowing no gaps. We then peeled off the backing from the adhesive side and, after lining the sheet up carefully, pushed the sheet against the wooden frame, pressing it down hard all the way round. We had the whole job, seven windows, finished by 8.30.
Because the acrylic is glass clear and 3mm thick, it looks just like glass. We also used brown magnetic seal, which is far less obvious than white. The acrylic should also be a better thermal insulator than the film was, can be cleaned very easily and can be lifted off in seconds if required. Because it is attached to the wooden window surrounds, it also stops condensation on the aluminium window frames and the air gap is a good sound insulator. We may trim arround the edge with a wood strip, but it does look pretty neat already and is a vast improvement over the film. As all the sheets are the same size and only 4.5mm thick including the seal, they will all stack only 30mm deep behind the sofa for summer storage and of course are infinitely reuseable, taking only seconds to refit.
The whole lot was only £222.97 including delivery, which I think is peanuts for years of repeated use. If anyone wants a picture of a finished window or any info on an acrylic supplier, I'd be glad to post.
Roger