Hello, last year we had an angled bungalow built with calcium silicate bricks. Above the doors and windows, apparently calcium silicate lintels were used (it looked like a U-shaped calcium silicate form filled with concrete). Inside, the walls were plastered with gypsum plaster.
A few weeks ago, we had a pleated blind installed on a fixed glazing window by a local interior contractor, screwed inside the reveal from below onto the window lintel. The next day, the blind came down again. The wall plugs had "slipped out." Okay, I removed the rest; the hole was so large that two wall plugs could have fit in it. I thought: better drill the hole myself than rely on the "professional." Here’s the catch: while drilling the new hole, my drill also slipped off course. Unfortunately, I don’t have any photos because the pleated blind is now reinstalled.
Why the drill slipped became clear to me: I must have hit a reinforcing bar exactly from below. I had the impression that the calcium silicate brick was very "soft." Nowhere else on the wall did the drill slip when drilling the hard calcium silicate bricks, but here, with little force, the drill slipped about half a centimeter. That was already very strange. Then came the surprise: the lintel seems to be partially hollow. I made a hole on the left and right outer edges of the lintel (window width 2m (6.5 feet)) and in both cases found the same: a cavity. If I estimate: from below there was about 4cm (1.5 inches) of gypsum plaster and calcium silicate brick, then approximately 1.5cm (0.6 inches) of a cavity, and then the threaded rod (whether there was concrete above it, I could no longer visually determine).
Since it’s a bungalow, I don’t expect much, but this definitely smells like a defect, doesn’t it? I’m sure I will only get anywhere with the builder if I commission an expert at my own expense now. What interests me more: now that the pleated blind will probably come down again (instead of the cheap 6mm (0.24 inch) plug supplied, I have now pressed in a Fischer FU8x40 plug, which still had minimal play but holds for now) — what else can I do to improve the fixing? Yesterday, I felt that each time I pulled out the test-inserted plug, the hole got about a millimeter bigger. The cavity is too small for a cavity plug to spread. Should I perhaps glue the plug with a two-component injection mortar (like from Fischer) the next time and inject as much as possible into the cavity?
A few weeks ago, we had a pleated blind installed on a fixed glazing window by a local interior contractor, screwed inside the reveal from below onto the window lintel. The next day, the blind came down again. The wall plugs had "slipped out." Okay, I removed the rest; the hole was so large that two wall plugs could have fit in it. I thought: better drill the hole myself than rely on the "professional." Here’s the catch: while drilling the new hole, my drill also slipped off course. Unfortunately, I don’t have any photos because the pleated blind is now reinstalled.
Why the drill slipped became clear to me: I must have hit a reinforcing bar exactly from below. I had the impression that the calcium silicate brick was very "soft." Nowhere else on the wall did the drill slip when drilling the hard calcium silicate bricks, but here, with little force, the drill slipped about half a centimeter. That was already very strange. Then came the surprise: the lintel seems to be partially hollow. I made a hole on the left and right outer edges of the lintel (window width 2m (6.5 feet)) and in both cases found the same: a cavity. If I estimate: from below there was about 4cm (1.5 inches) of gypsum plaster and calcium silicate brick, then approximately 1.5cm (0.6 inches) of a cavity, and then the threaded rod (whether there was concrete above it, I could no longer visually determine).
Since it’s a bungalow, I don’t expect much, but this definitely smells like a defect, doesn’t it? I’m sure I will only get anywhere with the builder if I commission an expert at my own expense now. What interests me more: now that the pleated blind will probably come down again (instead of the cheap 6mm (0.24 inch) plug supplied, I have now pressed in a Fischer FU8x40 plug, which still had minimal play but holds for now) — what else can I do to improve the fixing? Yesterday, I felt that each time I pulled out the test-inserted plug, the hole got about a millimeter bigger. The cavity is too small for a cavity plug to spread. Should I perhaps glue the plug with a two-component injection mortar (like from Fischer) the next time and inject as much as possible into the cavity?
K
Knallkörper6 Apr 2017 09:45Injection mortar will secure that well. From your description, it sounds like the lintel was not properly cast with concrete. This is, of course, a defect, especially because the concrete cover over the steel is missing.
@Mycraft: In our case, no drywall was installed. I supervised all construction phases myself, and nothing was "covered up" before plastering. As I said, through the drilled hole I could clearly see a roughly 4cm (1.5 inches) thick layer of gypsum and the underside of the sand-lime brick U-shell, then it went dark, about 1.5cm (0.6 inches) of air space, and after that I could see the steel reinforcement. And since the drill slipped so easily, I would agree with @Knallkörper here.
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