Wall anchors for AAC blocks

[kitjohnson]

My house walls are made of aerated autoclaved concrete blocks, aka AAC, superblocks, thermalite, etc.

 

Most people I've asked are like "any old anchor will do", but for more heavy-duty fixures, let's say hanging a hammock, for example, I want to make sure I don't accidentally rip a hole in the wall.

 

At Homepro I found these hooks, but I'm not sure if they will be any good or not.

 

Hook 1 and 2 both have some kind of anchor:

 

hook one

 

hook two

 

Hook 3 doesn't have any kind of anchor, so I'm wondering how it would every get anchored to anything.

 

hook three

[bankruatsteve]

I've put 100's of anchors into AAC with no problem.  But, a hammock?  Hmm.  Maybe put up a steel plate with eyelet just to have more (like 4) places of anchor.  

[grollies]

19 minutes ago, bankruatsteve said:

I've put 100's of anchors into AAC with no problem.  But, a hammock?  Hmm.  Maybe put up a steel plate with eyelet just to have more (like 4) places of anchor.  

Yep, I wouldn't hang a hammock on thermalite blocks without putting a steel plate on either side of the block and bolt right through at at least two points. Depends on how heavy the OP is.

[Pogust]

Special screws available but doubt that you can find it here. I bought in Sweden and took with me. Works very well and holds a heavy weight.

 

 

[kitjohnson]

A steel plate with an eyelet sounds like a great idea. I'll have a look to see what I can find.

 

@Pogust That screw looks like magic. Did I understand it right: self-tapping into wood, and self-anchoring into AAC? How expensive are they?

[cooked]

1 hour ago, kitjohnson said:

A steel plate with an eyelet sounds like a great idea. I'll have a look to see what I can find.

 

@Pogust That screw looks like magic. Did I understand it right: self-tapping into wood, and self-anchoring into AAC? How expensive are they?

Back home we had special plastic anchors that self tapped into a pre-drilled hole, normal wood screws could then be used. https://www.rakuten.de/produkt/ytong-duebel-gasbetonduebel-porenbetonduebel-fuer-leichtbeton-kunststoffduebel-871764056.html

Failing this I would cement any fixtures into a hole if I didn't want stuff to fall. Especially the non-load bearing, very light quality of AAC blocks that generally get used here need attention.

[Pogust]

11 hours ago, kitjohnson said:

@Pogust That screw looks like magic. Did I understand it right: self-tapping into wood, and self-anchoring into AAC? How expensive are they?

That is right, but you would have to pre-drill the wood here as it is too hard to force a 8mm screw through it. 8 x 120mm is 30 baht each. They hold 100-150kg pulling force each. I use them for door frames and hanging cupboard on walls.

[sometimewoodworker]

The fixings designed for AAC blocks are these

 

With the correct size drill and enough of them you will be able to anchor your steel plate to the wall. They will hold against a large shear force.

 

However a hammock will put an enormous pulling force ( as much as  several hundred Kg) on any fitting if you attach it the wrong way. The navies and merchant marine for hundreds of years knew that and so never rigged hammocks to the overhead beams using a pulling force always with a shear force

[mogandave]

Were it me, for a hammock I would drill through and put a nut and washer on the backside.

I would also be more concerned about a broken back than a hole in the wall.

[kitjohnson]

Excellent points about there being a strong pulling force, not just shear force, and also about the broken back.

 

I'll think about this carefully before attaching the thing, but a plate on both sides of the block sounds like a good start.

 

At this part of the house there are structural columns. I don't like the idea of drilling lots of holes into a column, as I feel it could weaken the integrity of the column itself, but I could be quite mistaken here.

[bankruatsteve]

8 minutes ago, kitjohnson said:

Excellent points about there being a strong pulling force, not just shear force, and also about the broken back.

 

I'll think about this carefully before attaching the thing, but a plate on both sides of the block sounds like a good start.

 

At this part of the house there are structural columns. I don't like the idea of drilling lots of holes into a column, as I feel it could weaken the integrity of the column itself, but I could be quite mistaken here.

A few holes in a support column would not be an issue but the likelihood of running into steel would.  I'd go somewhere else, if possible, with plates to spread out the load.

[kitjohnson]

7 minutes ago, bankruatsteve said:

A few holes in a support column would not be an issue but the likelihood of running into steel would. 

I appreciate your advice. When you say steel, do you mean the rebar inside the concrete column? (Sorry to sound like such a construction noob)

[bankruatsteve]

Just now, kitjohnson said:

I appreciate your advice. When you say steel, do you mean the rebar inside the concrete column? (Sorry to sound like such a construction noob)

Ya.  It obviously does not occupy the entire space but seems like it if attempting to drill a hole.

[mogandave]

Ya.  It obviously does not occupy the entire space but seems like it if attempting to drill a hole.

The first 3 on the plate go perfect, it’s that last one that always ends up a direct hit!

[kitjohnson]

8 minutes ago, mogandave said:

The first 3 on the plate go perfect, it’s that last one that always ends up a direct hit!

 

 

I can totally visualise this now!

[mogandave]

I think if you drill through the wall and use a backing plate you’ll be okay.

Don’t pull it too tight. The straighter the hammock hangs, the greater the force pulling on the wall when you get in...

[grollies]

Why on earth do you want a hammock indoors anyway.

 

If you have a garden stick up a couple of 3m concrete posts and sling it up in the shade.

[kitjohnson]

19 hours ago, grollies said:

Why on earth do you want a hammock indoors anyway.

 

If you have a garden stick up a couple of 3m concrete posts and sling it up in the shade.

 

Just realised the OP was a bit ambiguous. I wanted to hang it outside the house, but it's actually under an overhang of the second floor so it would be nicely shaded. Also quite near the kitchen for beers etc. 

[oldwelshman]

Check Hilti site for best, expansion bolts not used as they crack the block, best is chemical resin anchors we use them a lot in hospital installations they can be used in cracked or aerated concrete and bricks with frog. They also do screw and plug type which works in plaster board and concrete block.