My flat has white plastic windows dating from the last century – how posh that sounds – which tilt and turn but have no trickle vents. I tried to get a window company to put some in, but it was too small a job for them: so I had to do it.
DIY videos on U-tube make it look simple. Drill holes through the window frame and fix inner and outer grills over the holes. My opening windows are tilt-and-turn, and so contain rods and levers allowing them to do this Drilling holes might interfere with these, so it would be best to place the vents in the fixed windows. However, my flat is too far from the ground for safe access to the outside; so I had to use the opening windows.
By opening the windows fully inwards I was able to get access to the outside. I located the grills in the middle of the upper sash, drew around it with felt-tip pen and tried to drill holes right through to the other side inside the marked area. The following problems arose:
- Drilling too close to the top made contact with the interior mechanism, so I moved the drilling area down a bit to clear this.
- The interior of the window had various reinforcing struts of white plastic. Holes have to avoid these and go through to the other side.
- The building regulations for habitable rooms specify a vent area of 5000 square millimetres at least 1.7 metres above the floor. This area is difficult to achieve with drilled holes. What I did was cut out rectangular sections of plastic within the footprint of the vent cover using a vibrating saw. This made a neater job than drilling holes. Remember to leave enough material to hold the locating screws.
So far, they work well. Vented rooms seem fresh without opening a window, as I used to have to do.
So to summarise:
- If you have access to the outside, use the fixed windows.
- Use a vibrating saw (Bosch Multitool, in my case) to make the apertures.
- Watch out for interior reinforcement.
- If venting tilt-and-turn windows, work a bit lower then the centre line and watch out for other mechanisms.