I'm setting up wall-mounted bookshelves in my apartment and encountered something I hadn't noticed before: hollow "wood studs."
The wall is an interior wall with drywall, with "studs" spaced 45 cm apart, measured with a stud finder. When I was attaching the shelf, the drill went in a bit too quickly, which made me suspicious.
After a lot of test drilling, it seems the wall consists of 13 mm drywall, 19 mm wood, 32 mm cavity, and then 19 mm wood and 13 mm drywall again, see drawing, in places where the stud finder detects wood. I also inserted an inspection camera into the wall; see the picture for how the top of the "stud" looks, which confirms it's some kind of multi-piece construction.
I can't find anything online about hollow "studs" in interior walls, is this a common construction?
Now to my actual question, how do I mount a wall-mounted shelf in this?
- Is it still reasonable to screw the shelf into the "studs," or should I use molly bolts in the drywall?
- Molly bolt M6 in single drywall carries 40 kg
- How much can a short wood screw hold in 13 mm drywall and 19 mm wood?
- How much can a long wood screw hold in 13 mm drywall, 19 mm wood, 32 mm cavity, and 19 mm wood again? So an 80 mm long screw, that is.
Grateful for help, feels a bit like I've bought a shoddy construction...
The wall is an interior wall with drywall, with "studs" spaced 45 cm apart, measured with a stud finder. When I was attaching the shelf, the drill went in a bit too quickly, which made me suspicious.
After a lot of test drilling, it seems the wall consists of 13 mm drywall, 19 mm wood, 32 mm cavity, and then 19 mm wood and 13 mm drywall again, see drawing, in places where the stud finder detects wood. I also inserted an inspection camera into the wall; see the picture for how the top of the "stud" looks, which confirms it's some kind of multi-piece construction.
I can't find anything online about hollow "studs" in interior walls, is this a common construction?
Now to my actual question, how do I mount a wall-mounted shelf in this?
- Is it still reasonable to screw the shelf into the "studs," or should I use molly bolts in the drywall?
- Molly bolt M6 in single drywall carries 40 kg
- How much can a short wood screw hold in 13 mm drywall and 19 mm wood?
- How much can a long wood screw hold in 13 mm drywall, 19 mm wood, 32 mm cavity, and 19 mm wood again? So an 80 mm long screw, that is.
Grateful for help, feels a bit like I've bought a shoddy construction...
19mm wood then you can hang very heavy things. I assume it's raw wood paneling.
I would use screws that go 4-5 mm through the first wood.
If it's an Elfa system with a so-called suspension rail, I would use screws that are about 2+13+19+4, i.e. about 40mm. 5-6x40mm with a rounded head. I have put up quite a few shelves with Spax on plasterboard and 19mm raw wood paneling.
I would use screws that go 4-5 mm through the first wood.
If it's an Elfa system with a so-called suspension rail, I would use screws that are about 2+13+19+4, i.e. about 40mm. 5-6x40mm with a rounded head. I have put up quite a few shelves with Spax on plasterboard and 19mm raw wood paneling.
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The bookshelves are 80 cm wide and have two levels, so 1.6 shelf meters of books per shelf. A common measure is that 1 shelf meter = 40 kg, so 64 kg per shelf.
They hang on a rail with at least two attachment points.
How much does 19 mm wood + wood screw support per attachment point? It's very easy to find figures for molly plug but much harder for wood + wood screw.
They hang on a rail with at least two attachment points.
How much does 19 mm wood + wood screw support per attachment point? It's very easy to find figures for molly plug but much harder for wood + wood screw.
You typically don't screw through to the other wall. It will hold even if you only attach to the first wall. I don't see any advantage in screwing through, just a more expensive screw.R Rong said:
In your case, it mostly depends on the screw, primarily the thickness, i.e., 4, 4.5, 5, etc.R Rong said:
64 kg is very little.
That is 5mm Spax.
I don't think that 19mm raw wood plank is worse than OSB3, but maybe someone else can give an answer.
I don't think that 19mm raw wood plank is worse than OSB3, but maybe someone else can give an answer.
I would absolutely not be worried about hanging shelves that are to bear 64 kg with 5-6mm Spax. I wouldn't worry about hanging double that in 19mm råspont.
Tear down the wall to hang up shelves?
Have you made the assessment that the wall is too weak for what TS wants to do?