I'm in the process of fitting blinds above a window alcove. This window is very wide (5m) and the exterior of the building is from the 20s/30s I believe although the interior is new build. It used to be a furniture shop and is now a flat. I drilled through the plasterboard and hit what I believed to be a steel lintel. I changed drill bit from masonry to hss and continued through the lintel. After a short while the drill punched through the lintel into a cavity above. A short gap further there seems be another surface. Which makes a cracking noise when drilled through (possible tiling for bricks? I have no idea). After drilling the holes for one of the brackets there seems to be some type of fluff dragged back out the holes by the drill. This only happened for one of the three brackets I've drilled so far. The fluff looks a bit like tuna but has a fluff texture.
Second issue is that I'm trying to follow this video:
Self tapping screws into the lintel to create a strong fixing as the blinds are very heavy. However this only appears to work for some drill holes and not for others. That is some screws seem to make a sturdy fixing and others fall out, not griping into the lintel at all. I have no idea how to overcome that as the brackets will not hold up when the blind is connected to them. Any help is much appreciated. I'm at a loss now.
Second issue is that I'm trying to follow this video:
Self tapping screws into the lintel to create a strong fixing as the blinds are very heavy. However this only appears to work for some drill holes and not for others. That is some screws seem to make a sturdy fixing and others fall out, not griping into the lintel at all. I have no idea how to overcome that as the brackets will not hold up when the blind is connected to them. Any help is much appreciated. I'm at a loss now.
