Slab Thickness

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Slab Thickness

Post by Rider888 » 13 Jul 2020, 8:45 am

Is anyone out there a qualified Engineer or builder?

Asking because I am trying to find out the NSW AUS standard for the thickness of a slab in a residential apartment block so that when I drill my bolts into the slab for my safe in the apartment, I dont end up punching through to the apartment below me especially when NSW requirements for bolts is about 90mm long to secure a safe

Thank you

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Re: Slab Thickness

Post by moudzj » 13 Jul 2020, 8:52 am

Hi mate,

Engineer/builder here.

These days, minimum thickness of a conventional steel reinforced suspended slab is 200mm. Older slabs are thinner. No way to tell the thickness of your slab without checking plans or asking, could vary for multiple reasons, even throughout the building.

What you seriously need to be careful of is Post Tensioned slabs. Last thing you want to be doing is drilling through and snapping one of these cables. So, unless you ask the body corporate for this info, there is really no way to tell without risk. They would probably disallow you to drill thru the slab regardless.

Your absolute best course of action is buying a safe >150kg and avoiding drilling.

Goodluck.
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Re: Slab Thickness

Post by Rider888 » 13 Jul 2020, 9:02 am

moudzj wrote:Hi mate,

Engineer/builder here.

These days, minimum thickness of a conventional steel reinforced suspended slab is 200mm. Older slabs are thinner. No way to tell the thickness of your slab without checking plans or asking, could vary for multiple reasons, even throughout the building.

What you seriously need to be careful of is Post Tensioned slabs. Last thing you want to be doing is drilling through and snapping one of these cables. So, unless you ask the body corporate for this info, there is really no way to tell without risk. They would probably disallow you to drill thru the slab regardless.

Your absolute best course of action is buying a safe >150kg and avoiding drilling.

Goodluck.


Thanks but I dont believe the 150kg safe weight thing applies to H-Cat - in fact Im sure it doesn't. I only have a small safe at on transit apartment and a larger safe at the main property
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Re: Slab Thickness

Post by Blr243 » 13 Jul 2020, 9:22 am

Remember that a hammer drill is not only drilling but also delivering blows at the same time.....if u attempt to drill a 70 mm hole in a slab of 100 mm there’s a high probability that u will smash out a big exit hole in the bottom of the slab ....once while watching a handrail installation contractor working on veranda slabs on a multi level unit building , I saw evidence of his lack of care
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Re: Slab Thickness

Post by TassieTiger » 13 Jul 2020, 10:01 am

Curiosity Question - would body Corp need to know storage of firearms on premises regardless? Would insurance be voided if you didn’t ?
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Re: Slab Thickness

Post by moudzj » 13 Jul 2020, 10:18 am

TassieTiger wrote:Curiosity Question - would body Corp need to know storage of firearms on premises regardless? Would insurance be voided if you didn’t ?


No, I dont think so.
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Re: Slab Thickness

Post by Tiger650 » 13 Jul 2020, 2:06 pm

Not sure how Plod would know what length dynabolts you used ?
I wonder if chemsets are available in shorter lengths ?
Plod would have his work cut out verifying the installed length of a chemset.
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Re: Slab Thickness

Post by moudzj » 13 Jul 2020, 2:24 pm

Tiger650 wrote:Not sure how Plod would know what length dynabolts you used ?
I wonder if chemsets are available in shorter lengths ?
Plod would have his work cut out verifying the installed length of a chemset.



No way to tell with dynabolts. I wouldnt worry about using anything longer than 50mm even though ive used 100mm length bolts on mine. Remember that screw anchor bolts have dimensions written on the bolt face.

Regardless, Possibility of slab being PT poses a bigger issue.
Last edited by moudzj on 13 Jul 2020, 2:25 pm, edited 1 time in total.
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Re: Slab Thickness

Post by Rider888 » 13 Jul 2020, 6:46 pm

Thanks everyone
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Re: Slab Thickness

Post by Blr243 » 13 Jul 2020, 6:48 pm

I also thought of Cherm sets. Only a few years ago I found out about drop in anchors ( the type you punch withhammer and punch to expand the walls. ) Fantastic as long as u are very certain of concrete strength behind it.
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Re: Slab Thickness

Post by Rider888 » 14 Jul 2020, 11:13 am

I also forgot to mention that, for me, these cannot be permanent as I move houses every year or two hence dynabolts would be the simplest to remove my safe
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Re: Slab Thickness

Post by TassieTiger » 14 Jul 2020, 3:33 pm

What about those blue industrial strength concrete screws ? I used them to secure gate rails and they cracked concrete (Not 100mm thick) before They broke ?
I cannot recall name - but larger ones have hex key drive...drill hole and then thread cuts like self tap - into concrete - double up on numbers maybe and fill heads with resin ?
You can write to commissioner and get approval for things like that - given your building may well be protected via entry etc - they might be open to suggestions...
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Re: Slab Thickness

Post by Blr243 » 14 Jul 2020, 6:21 pm

I think the blue ones are called tap cons and they are actually been around for 30 years. I think they give u a drill bit in the package. Ankascrew is the name of the ones TT refers to. I have good results all the time with those in concrete but not really in crumbly brick so much
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Re: Slab Thickness

Post by Blr243 » 14 Jul 2020, 6:23 pm

I’m so glad things have improved big time from the old days of dyna bolts .....they are such a luck dip ....when they take up good and quick it can be a rewarding surprise and give u a little buzz
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Re: Slab Thickness

Post by JSS » 15 Jul 2020, 9:55 pm

TassieTiger wrote:What about those blue industrial strength concrete screws ? I used them to secure gate rails and they cracked concrete (Not 100mm thick) before They broke ?
I cannot recall name - but larger ones have hex key drive...drill hole and then thread cuts like self tap - into concrete - double up on numbers maybe and fill heads with resin ?
You can write to commissioner and get approval for things like that - given your building may well be protected via entry etc - they might be open to suggestions...


They're called Excalibur bolts.

Personally to play it safe if you're worried about the slab i'd just use 50mm dyna bolts or chemset in some threaded rod 50mm deep You're not going to hit anything vital at that depth, most slabs like that should have 50mm cover before you even hit mesh. Nobody is ever going to know they're not 100mm and they're not going to budge an inch.
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Re: Slab Thickness

Post by moudzj » 15 Jul 2020, 10:37 pm

JSS wrote:
TassieTiger wrote:What about those blue industrial strength concrete screws ? I used them to secure gate rails and they cracked concrete (Not 100mm thick) before They broke ?
I cannot recall name - but larger ones have hex key drive...drill hole and then thread cuts like self tap - into concrete - double up on numbers maybe and fill heads with resin ?
You can write to commissioner and get approval for things like that - given your building may well be protected via entry etc - they might be open to suggestions...


They're called Excalibur bolts.

Personally to play it safe if you're worried about the slab i'd just use 50mm dyna bolts or chemset in some threaded rod 50mm deep You're not going to hit anything vital at that depth, most slabs like that should have 50mm cover before you even hit mesh. Nobody is ever going to know they're not 100mm and they're not going to budge an inch.



Absolutely not true. Minimum cover can be as little as 20mm and usually not ever more than 30mm, and that's assuming works executed properly, which with concrete, it never is.

OP since you are moving so often just get a heavy save and enough with the absurdities.
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Re: Slab Thickness

Post by Rider888 » 16 Jul 2020, 6:40 am

moudzj wrote:
JSS wrote:
TassieTiger wrote:What about those blue industrial strength concrete screws ? I used them to secure gate rails and they cracked concrete (Not 100mm thick) before They broke ?
I cannot recall name - but larger ones have hex key drive...drill hole and then thread cuts like self tap - into concrete - double up on numbers maybe and fill heads with resin ?
You can write to commissioner and get approval for things like that - given your building may well be protected via entry etc - they might be open to suggestions...


They're called Excalibur bolts.

Personally to play it safe if you're worried about the slab i'd just use 50mm dyna bolts or chemset in some threaded rod 50mm deep You're not going to hit anything vital at that depth, most slabs like that should have 50mm cover before you even hit mesh. Nobody is ever going to know they're not 100mm and they're not going to budge an inch.



Absolutely not true. Minimum cover can be as little as 20mm and usually not ever more than 30mm, and that's assuming works executed properly, which with concrete, it never is.

OP since you are moving so often just get a heavy save and enough with the absurdities.


As mentioned, the heavy safe regulation doesn't apply to Cat H
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Re: Slab Thickness

Post by Member-Deleted » 16 Jul 2020, 7:31 am

not to derail this thread but it creeps me out that after opening this thread the pop up ads I now get are for Bundrex Steel Fiber Reinforced Concrete ... I don't really understand how the interwebz works but what has happened to my usual selection of ads for holsters, 4WD accessories and Russian brides? :lol:
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Re: Slab Thickness

Post by JSS » 16 Jul 2020, 8:31 am

moudzj wrote:

Absolutely not true. Minimum cover can be as little as 20mm and usually not ever more than 30mm, and that's assuming works executed properly, which with concrete, it never is.

OP since you are moving so often just get a heavy save and enough with the absurdities.


I've never seen less than 40mm especially in suspended slabs, perhaps residential is a bit lax, but you certainly don't get away with that in civil where every pre-pour is inspected & signed off by engineers.
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Re: Slab Thickness

Post by Blr243 » 16 Jul 2020, 12:02 pm

Nobody is watching concretors when they are pouring. And they pull bar chairs out whenever it suits them. And if they are seen nobody tells them off because they are too scared the concretor will hit them over head with shovel
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Re: Slab Thickness

Post by JSS » 16 Jul 2020, 2:20 pm

You must be talking about residential again. Generally we'd have a concrete tester testing every truck load, an engineer or two (as they seem to travel in pairs) and a at least one supervisor during an average pour on the jobs our company used to do, the steel & coverage would get checked & signed off then the final pour checked off along with all the testers dockets. Mind you they weren't house slabs & driveways, you're right there. nobody gives a crap about that kind of stuff. :lol: :drinks:
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Re: Slab Thickness

Post by Rider888 » 16 Jul 2020, 3:17 pm

So it would be fairly safe punching a 50mm Dynabolt into an apartment floor?
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Re: Slab Thickness

Post by JSS » 16 Jul 2020, 4:32 pm

I'm pretty sure you won't have any hassles at all. I've done it before in an apartment i own when i lived in it 20 years ago, it wasn't a gun safe just a small valuables safe. i just put a couple of small dynas in, and you wouldn't believe it but the building is still standing today. :D
If you're not sure though you could always just find an internal wall, locate a stud and bolt it to that assuming that's legal in your state (i'm pretty sure it is in most).
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Re: Slab Thickness

Post by Ziege » 16 Jul 2020, 5:15 pm

If you're relocating it a lot then dynabolts are a pain in the ass, just use the screws and plugs, save yourself the pain, don't drill deeper than 80mn if you don't know the slab thickness, with ant luck if it's older it will be 160mm minimum, as the original reply, 200mm is the new standard
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Re: Slab Thickness

Post by Rider888 » 16 Jul 2020, 5:42 pm

Ziege wrote:If you're relocating it a lot then dynabolts are a pain in the ass, just use the screws and plugs, save yourself the pain, don't drill deeper than 80mn if you don't know the slab thickness, with ant luck if it's older it will be 160mm minimum, as the original reply, 200mm is the new standard


Can you please tell me why dynabolts are pain in the arse? I have dynabolts for my safe now and my understanding is that I just undo the nut, lift the safe off the bolts then tap the remainder of the bolt into the slab and wallah or am I wrong?
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Re: Slab Thickness

Post by Ziege » 16 Jul 2020, 6:02 pm

That until one bends, cracks, twists, etc, etc, etc, etc, I have put in literally thousands, hence why I don't use them anymore, neither do the majority of the cyclone rated builders I have/do work for, I now fabricate instead of stand frames and posts, and the options they use now are more expensive, in some cases twice as much as a dynabolt, but they're just not worth the arse ache

Thought I might add that they also loosen easier than most other fixings, if he buys a reputable bolt option he can use the same in the future and buy once also. But each to their own.
Last edited by Ziege on 16 Jul 2020, 6:05 pm, edited 1 time in total.
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Re: Slab Thickness

Post by Rider888 » 16 Jul 2020, 6:04 pm

Ziege wrote:That until one bends, cracks, twists, etc, etc, etc, etc, I have put in literally thousands, hence why I don't use them anymore, neither do the majority of the cyclone rated builders I have/do work for, I now fabricate instead of stand frames and posts, and the options they use now are more expensive, in some cases twice as much as a dynabolt, but they're just not worth the arse ache


What would you recommend I use instead of dynabolts? remembering i need a bolt that can be removed
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Re: Slab Thickness

Post by moudzj » 16 Jul 2020, 8:54 pm

Rider888 wrote:
Ziege wrote:That until one bends, cracks, twists, etc, etc, etc, etc, I have put in literally thousands, hence why I don't use them anymore, neither do the majority of the cyclone rated builders I have/do work for, I now fabricate instead of stand frames and posts, and the options they use now are more expensive, in some cases twice as much as a dynabolt, but they're just not worth the arse ache


What would you recommend I use instead of dynabolts? remembering i need a bolt that can be removed


Ankascrews are far easier to use, and much better for your application. Have them in my two safes.
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Re: Slab Thickness

Post by Ziege » 18 Jul 2020, 7:46 pm

Anka screws or coach screws with good plugs like Ramset plugs, rattle them in or use a socket wrench, and same to remove/reuse
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Re: Slab Thickness

Post by Blr243 » 18 Jul 2020, 8:18 pm

Companies like Ramset or hilti usually have a free advice phone number where u can get technical advice from supposedly experts in Relation to various situations Of concrete fastening methods. Sometimes they are great. Sometimes they are bloody average bordering on useless
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