Screw directly into aerated concrete

[cryssarn]

Hello,
I have just moved into an apartment from the 1950s. When I walked around and tapped on the walls, I noticed that some almost sounded like plaster. However, after seeing someone's failed attempt to hang shelves in the closet, I noticed that it was very porous concrete, about as thick as a plasterboard. Inside it was even more porous. They managed to get the shelves up, but I'm afraid to take them down and see how they're hung.
I tried drilling without hammer with a 5mm drill bit. It went in a bit, and then it felt like I hit some type of stone. The drill slid to the side and the hole instead became uneven, too shallow and about 7mm. After seeing the butchered wall in the closet, I wasn't keen to try more than that. I then looked at aerated concrete screws, but nothing matched the dimensions I needed. Since I saw a couple of regular nails in some of those walls, I tried putting a nail in the closet. It went in without a problem, and it held. Tried a regular wood screw and it went in as easily as if it were plaster. It also held well. So I put up my small particleboard shelves from IKEA directly with wood screws. 3 shelves with 3 screws each, max about 1kg weight... as well as 1 shelf with 2 screws and a max weight of about 600 grams.
Do you think this will stay up? I've never encountered walls like this before. It feels like the screws are holding tighter than just directly in plaster, but can you trust it to stay up?

 

[jonaserik]

You will have to wait and see, no glass/porcelain on the shelves just, only soft goods, it's possible to get it to stay if you take it the same as now, but some longboards horizontally, with many screws into the wall and then brackets attached to them, make sure that what is to support the shelves stands against the floor, then it's only for tipping outwards that those in the wall need to hold.

 

[cryssarn]

You have to give it some time, just no glass/ceramics on the shelves, only soft goods. It's possible to get it to hold if you use the same method as now, but with some long horizontal boards with many screws into the wall and then brackets attached to them. Make sure that what should support the shelves is resting on the floor, then it's just for tipping outward that those in the wall should hold.

It's like light plastic toys on two, then a couple of light small photo frames and some candles on two. Do you mean that the screws might be pulled out of the holes over time?
"It's possible to get it to hold if you use the same method as now"...what did you mean by that?

 

[AXS]

I do it like this at home, screw directly into the wall. Handles a lot of weight but not movement at all.

I use drywall screws as they are really hard.

 

[cryssarn]

I do it at home, screw straight into the wall. It can handle a lot of weight but not any movement at all.

I use drywall screws because they are really hard.

So make sure it's secure, keep an eye on it, but don't push or move the shelf, aka don't jiggle it to check if it's secure.

 

[AXS]

Exactly!

 

[Pyka]

Had the exact same issue when we lived in a 50s apartment.
Filled the hole with putty, used a concrete plug.
Let it dry.
Then inserted the screw.
The 32-incher didn't fall down in the kitchen.

 

[mugatu]

https://www.ahlsell.se/10/infastning/skruv/specialskruv/1534903/#
this screw works well directly in lightweight concrete. It can also be screwed directly into regular concrete if pre-drilled with a 4mm drill.

 

[cryssarn]

Had exactly the same issue when we lived in an apartment from the 50s.
Filled the hole with putty, inserted a concrete plug.
Let it dry.
Then inserted the screw.
The 32-incher didn't fall down in the kitchen

The problem is just that I didn't get deep enough to insert the plug. Despite not using the hammer function, the drill jumps upward and sideways.

 

[cryssarn]

[link]
this screw works well directly in lightweight concrete. It can also be screwed directly into regular concrete if you pre-drill with a 4mm drill bit.

Thanks, will save the page. Not sure how good it is to replace the screws and use the same hole

 

[Pyka]

The problem is just that I didn't get deep enough to fit the plug. Even though I'm not using the hammer function, the drill jumps upwards and to the side.

I recognize that. It got harder in some spots.
I think we had brick behind some render that was like sand. Red powder came out during drilling.

You might need to try turning on the hammer function and a good concrete drill bit.

 

[mugatu]

Thanks, I will save the page. I don't know how good it is to change the screws and use the same hole

you usually only have one chance if you're screwing directly. If you start backing out or replacing the screw, it might be over

 

[cryssarn]

you often only have one chance if you screw directly. If you start backing out or replacing the screw, it can be over

Yes, that's true. I'll just leave it then, if I notice it starts to loosen I'll order the screws and make new holes. Otherwise, I'll end up with 12 extra holes in the walls.

 

[tommib]

It sounds very much like the first layer is plaster and not some lightweight concrete. What's behind it is harder to answer.

I would investigate the wall construction a little more before making any definitive decisions. Maybe check with the board? Maybe post pictures here?

 

[cryssarn]

Recognize that. It got harder in some places. I think we had brick behind some render that was like sand. Red powder came out during drilling.

You might need to try using the hammer function and a good concrete drill bit.

Using a Bosch drill if I remember correctly. Tried the hammer function too, but it just widened faster. Maybe a 4mm would be better. The question is whether my temporary solution will work for a little while. It's probably about 3-400 grams/screw approximately.