Submitted by Im_A_Model t3_11bhbq5 in DIY
I need to hang a heavy oak shelf onto an aerated concrete wall and have run into some problems.
The shelf is hanging on hidden brackets and I have used some specific rawlplugs for aerated concrete made to hold 16 kg each but the shelf is unstable because the aerated concrete crumbles inside the hole.
Are there any special type of rawlplugs for the job or is there other solutions?
Thanks for the advice. Just went and bought some epoxy for the job and went with the first option to put the plug into the hole. Now I'm just waiting for it to cure and then I will try to mount it again
Hilti HY-200A adhesive with threaded rod. You can get threaded rod to match whatever anchor the shelves came with. For aerated concrete you should get the mesh sleeve as well. If its outdoor get the hot dip galvanized threaded rod.
For oak I was always told to go for stainless rather than galvanised (idk if it's a US/UK nomenclature thing) as the oak will corrode anything other than stainless, particularly if there's likely to be any water involved. I have also confirmed this through slightly painful experience!
Stainless steel is stainless steel, galvanized steel is steel with a zinc coating. Stainless is much more expensive but also more resistant to corrosion than galvanized, which costs almost the same as normal steel.
Sort of. The tannins in oak will react with iron which is why stainless is recommended. You'll get unsightly black marks on the steel and the oak surrounding it.
TIL! Thanks that's great info. I really only deal with metal, but this could definitely be good to know in the future.
This, but I recommend something other than Hilti if you want to save some money. There are plenty of alternatives that will do the same thing without the Hilti brand premium you pay $$$.
You're not wrong that its expensive. I order pallets of it regularly for work and I've used it in this exact condition and had the connection engineered. I almost always go with what our engineer recommends, he is excellent.
If that isn't enough, you can try adding more brackets as well. If they are really heavy, you might just have to build proper supports that go to the ground.
FYI, the 16 kg rating is for shear (the anchor pushing sideways on the wall) loads. Mounting a shelf puts a lot of tension (pulling out of the wall) on the anchors, which almost none of them are rated for.
Nicely explained. I just get apoplectic with rage watching new AV technicians trying to justify mounting an articulated bracket with drywall plugs
"but each is rated to 75lbs I'm using 4 and this all weighs less than 100lbs! I've done it before bro chill out"
I won't chill, you're going to fucking kill a child, do not show up tomorrow if this isn't fixed in the next 30 minutes.
Maybe even worse, an articulated bracket is subject to being moved and wiggled around, which drywall anchors also suck for.
What do you mean, sideways? Do you mean downwards? Or into the wall, opposite of outwards? Why would they be rated for sideways force? How and when would sideways force be applied? Literally cannot figure out what it means in the context.
Sideways as in in the plane of the wall. Up, down, left, right, or any angle in between those. Usually the load is down because well, gravity. Just not in toward the wall or out away from the wall.
So you meant lateral? Why not say that? You've broken like three conventions at once, it's very confusing.
Because a bunch of laypeople may not know what lateral means, and I'm trying to make the information as accessible as possible. That's also why I explained shear and tension.
But also because lateral is no more accurate or precise than sideways. Lateral loads are horizontal, as made distinct from vertical loads. The most correct terms are shear and tension loads, or possibly in-plane and out-of plane loads.
While using epoxy is certainly one way of putting in anchors to aerated concrete it certainly isn’t the only or IMHO the best way.
the best way is to use “saw steel anchors” they are specifically designed for AAC blocks and I have used several hundred of them. My walls are all AAC (aerated concrete)
an mage is at https://sc01.alicdn.com/kf/HTB1QHWYvTlYBeNjSszcq6zwhFXaM/200138850/HTB1QHWYvTlYBeNjSszcq6zwhFXaM.jpg
Thanks for the tip, that looks interesting. I will have to find out what they're called in Danish as I have never seen those before
Epoxy virker (limanker).. Jeg har selv gjort det med Egehylder med skjulte stagbolte. Du skal bare sikre dig at de er dybt nok i. (80-100mm)
Tip: Jeg borede hul til stagbolten fra bagsiden af hylden og fræste en rille op fra undersiden af hylden til at montere møtrikken så montagen er helt skjult
Super, tak. Lader lige epoxyen sidde indtil i morgen, men umiddelbart ser det fast ud. Hylden jeg har, har jeg fået lavet af en snedker, så der er styr på beslagene, det var bare lige væggen, der drillede.
English: just saying I will leave the epoxy till tomorrow but it looks solid so far
I believe what you're looking for is "chemical anchor". It's a type of epoxy that's made for putting steel rods into concrete, forever.
Depending on your brackets and how much space there is inside the shelves, best would be to use chemical anchor to stick threaded rod into the holes, wait for it to cure, and then screw on the shelf brackets with nuts onto the threaded rod.
Edit: Forgot to add - the longer you can make your anchor the better. 6 inches if you can :)
For heavier weights they’re just not designed for that.
I actually cut mine out installed standard bricks where I needed mounts, plastered to make good and then used metal expanding bolts.
You could also try resin / chemical bonds but I have no knowledge of that.
As i clicked on this i thought i bet someone says something crazy like re build the wall. Top comment. This sub cracks me up, least its not his wall cracking. Ill see myself out
Thanks, it's a bit circumstantial for me though 😅
Use the correct anchors and you have no need of all that fafe
i have cabinets hanging on single French cleat battens 30mmx50mm, that hold upwards of 50kg using 3~5 3x3” screws in saw steel anchors
You need more contact area between the anchors and wall material. So get longer anchors (longer equals more pull out resistance). Anchor can be anything really, a length of threaded rod works well if it’s thick enough and you use enough to support the load.
Also drill the hole a good bit bigger than the anchor bolt and use either regular concrete or good epoxy to set the anchor. You want the anchor to only be contacting the adhesive and the adhesive to unify with the spongy wall material. Another benefit of the larger hole is the ability to exactly level the anchor rods as the adhesive is setting.
pull out game is strong
We had a solid cedar fireplace mantle installed and it was interesting how they did it. They drilled holes into the brick with a masonry drill, then had rods that looked like rebar, and set them into the holes with epoxy gel. They propped them up so they'd be somewhat level. Once they set, they drilled holes into the back side of the mantle, coated the protruding pegs with glue, and set it in place.
This is a gotta-get-it-right-the-first-time kind of thing but might work for your situation.
You need to use threaded rods and chemical anchor. And drill dep enough because those walls can almost support nothing.
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Had to google aerated concrete wall. Learnt something. My previous home, the concrete blocks were substandard, and crumbled when drilling into them. I would have love to have known this information.
Aerated? Never heard that term
RexiReddit t1_j9xv2ce wrote
Try filling the holes with an epoxy gel, then push the plug into the hole. Make sure it stays aligned as it cures. Another method is to let the epoxy cure, then drill the epoxy for the brackets.
Search for “anchoring adhesive. ”