We recently completed our first international assignment. The problem of metal casement windows has bugged us for a long time. The window casements and top hung lights remarkably tend to warp and deform giving rise to draughts through awkward small and slightly tapering cracks. These are unsuitable for draught strips and have been professionally remedied by specialist companies using silicone sealants applied to the frame and a release agent to the casements. We have followed this same process noting that it is crucially important that the frame is perfectly clean and free of all dust, flaking paint and is dry before applying the silicone. On closing the window the silicone forms a perfect seal filling all the gaps of whatever size and shape that they may be. Once cured, typically after four or five hours depending on the thickness and type of silicone and on the humidity, the window can be opened and the release agent, in our case simply liberally applied Vaseline, must then be cleaned off both surfaces with an absorbent cloth and washed with detergent and water a couple of times then wiped clean with water. Any overspilt sealant that may have squidged out can be carefully cut away with a sharp knife it is better to tool the silicone back to the frame on closing the window.
The results were instantly appreciated by the occupants, noticeably quieter, noticeably draught free which meant warmer in winter and cooler in summer with less energy required for air cooling for a shorter season during which small amounts of heating would be needed.
Serendipitous and remarkable additional benefit is that the occupants are getting bitten far less by insects than previously presumably because they cant get in through the cracks that I sealed up. 🙂