In the hallway of the attic in our old building, I noticed that the floor is sagging and no longer level. I checked underneath. The floor structure consists of 20mm (about ¾ inch) polystyrene insulation (now more like 17mm (⅔ inch)) and 20mm (¾ inch) chipboard. Some of the chipboards were apparently installed without tongue and groove joints, so over the years they have pressed into the polystyrene. There is carpet laid directly on top.
The question now is how to level the floor again. I assume that the old structure needs to be removed since it is no longer usable. The new structure should be roughly the same thickness as the old one, around 40mm (1 ½ inches). I was thinking about using 20mm (¾ inch) polystyrene with 18mm (¾ inch) or 22mm (⅞ inch) OSB boards (of course with tongue and groove). Does this make sense? Would 18mm (¾ inch) OSB be enough, or would it definitely need to be 22mm (⅞ inch)? Or am I completely off track, and is there a better solution?
The question now is how to level the floor again. I assume that the old structure needs to be removed since it is no longer usable. The new structure should be roughly the same thickness as the old one, around 40mm (1 ½ inches). I was thinking about using 20mm (¾ inch) polystyrene with 18mm (¾ inch) or 22mm (⅞ inch) OSB boards (of course with tongue and groove). Does this make sense? Would 18mm (¾ inch) OSB be enough, or would it definitely need to be 22mm (⅞ inch)? Or am I completely off track, and is there a better solution?
K
Keishadow21 Feb 2020 15:41First of all, thanks for all the information. I know that a proper solution would be a screed with underlayment panels and so on. What concerns me, however, is the height of about 40mm (1.5 inches) that I would like to maintain so that the hallway is not significantly higher than the rooms. A proper solution would certainly be a few centimeters higher?
The base is a concrete slab. On top of that, I intended to lay 6mm (0.24 inches) laminate plus 2mm (0.08 inches) impact sound insulation. This would already make the new floor a few millimeters higher than before, but still within a reasonable range. With about 7m² (75 sq ft), this hallway is not particularly large and does not experience heavy use. It will only be walked through briefly to access the rooms.
The base is a concrete slab. On top of that, I intended to lay 6mm (0.24 inches) laminate plus 2mm (0.08 inches) impact sound insulation. This would already make the new floor a few millimeters higher than before, but still within a reasonable range. With about 7m² (75 sq ft), this hallway is not particularly large and does not experience heavy use. It will only be walked through briefly to access the rooms.
Vicky Pedia21 Feb 2020 20:17Everything is much simpler on a concrete slab, as it is load-bearing. So, leveling and fiber cement boards are used. However, since it is clearly the foundation slab, thermal insulation should already be in place. In these areas, I use rigid foam boards with an aluminum foil facing. These are available in various thicknesses.
Vicky Pedia schrieb:
Since it is obviously the ground slab, there should definitely be thermal insulation installed. Just as a note, here is an excerpt from the original post:
"In our older building, I noticed in the attic hallway ..."
That’s regarding the topic of the "obvious ground slab"!
K
Keishadow21 Feb 2020 20:59KlaRa schrieb:
Just a note, an excerpt from the original post:
“In the hallway on the top floor of our old building, I noticed…”
That’s regarding the topic of the “visible concrete slab”!Does “old building” mean that the floor consists of wooden beams? I’m not familiar with the exact definition. To me, “old building” refers to anything that is relatively old. Yes, concrete ceiling. I don’t know exactly how thick it is. But 40mm (1.6 inches) is certainly too thin to properly accommodate leveling, impact sound insulation, and the concrete slab, right? Or in other words, what would be the minimum thickness needed to do this properly?Vicky Pedia21 Feb 2020 21:02KlaRa schrieb:
Just as a note, an excerpt from the original post:
"In the hallway of the attic in our older building, I noticed ..."
That about the topic of an "obvious concrete slab"! This happens to me more often as I get older, thanks!
Keishadow schrieb:
Does “old building” mean that the floor consists of wooden beams? I don’t know the exact definition. To me, an old building is anything that’s relatively old. Yes, a concrete ceiling. I just don’t know what type it is exactly. But 40mm (1.6 inches) is certainly too little to properly install leveling, impact sound insulation, and the floor slab, etc., right? Or, to put it another way, what would be the minimum height needed to do this correctly? “Old buildings” are generally considered residential or commercial buildings that have been in use for 25 (service) years or more.
And 40mm (1.6 inches) is indeed quite tight as the maximum total height for the entire assembly. A proper impact sound insulation that lives up to its name would hardly be possible to install when you also take into account the necessary load distribution layer (e.g., wood chipboard) within that 40mm (1.6 inches) limit.
With gypsum fiber boards, like KNAUF Brio for example, the substrate must be very even. So, a surface leveling on top of the raw ceiling combined with mechanical preparation of the substrate would be required.
A special solution is possible, though! However, most builders tend to shy away from the cost involved (I don’t mean to imply that here).
Keyword: “Turbolight(R) system.”
I had nearly 5,000 m² (53,800 ft²) of an insufficiently load-bearing ceiling structure refurbished in a highly frequented commercial area in Berlin using this system. And it works!
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