Pouring a 30"×40" concrete pad on top of concrete floor?

[Aftermath]

Si. And does the pump have electricity? I can follow all that. A 8" drain pipe will only move so much water as will a 40 GPM pump.

But a 8" drain in a 30' x 40' x 10' tall room is still a 8" drain in a 30' x 40' x 9'6" tall room. Same for a 40 GPM pump.

The floor is the floor either way and 2 foot of water in a room with a 10 foot ceiling is still 2 foot of water in a room with a 9 1/2 foot ceiling. I've been stumped by simpler problems before so it's definitely not your fault if I don't understand. Maybe tequila will help.

I can't help myself...let's use your dimensions....30'x40'. allowing for 6" of liquid...1,036,800 cubic inches....4,488.3 gallons

Now, lift a safe 6" on a 30"x40" whatever. The room volume has now diminished by 6"x30"x40". 7200 cubic inches....31.2 gallons

The drain system won't even realize the diminished capacity of the room

 

[Aftermath]

@Aftermath I thought about the moisture issue and just framing out a base, that but I want this safe secured. I'm not concerned about anyone dragging this safe back up the stairs, but an unsecured safe can be tipped over and pushed onto its back in 60 seconds and then it's very vulnerable to a simple prying attack. (And of course I''ll be putting in motion sensors, a wifi camera, and a water sensor - all on battery backup). And roger on the dogs and the mean woman too

@hollowoutadime I would love to go taller like you're suggesting (12" was my first idea), but the safe moving company uses a hydraulic stair climber that can lift a maximum of 8" so I'm somewhat limited.

@redneckbmxer24 @ironpony52 good call on the carpet just being a sponge to hold moisture against the safe. You're right. I'm deleting that from my plan. It will just be the concrete pad plus a 1/4" sheet of solid HDPE on top as a moisture barrier.

@everyone - yes the room does have an 8" floor drain. I'm going to look into installing a sump pump as well, although that will be a future project. But the prior owner said he had never had water in the basement in the 33 years he lived here and I believe him, the carpets and drywall are all original and there isn't a single water stain anywhere.

You can still attach to the floor under whatever stand....just use longer anchor bolts.

If the safe is in direct contact with the concrete (BAD IDEA) you will only need a bolt that is about 3" longer than the thickness of the safe floor. This will allow you about a nuts depth to secure without having a long piece of bolt sticking up.

If you lift the safe 6" off that concrete on some other type of stand or base (DAMNED GOOD IDEA) you will now need anchor bolts that are 9" longer than the safe floor thickness.

Either way...a 4" angle grinder gets me in your Fort Knox safe in under an hour.

EDIT: When I use these type of bolts, I attach the washer and nut up near the point of the bolt that is designed for hammer impact. Drive the thing into place until I am squashing the washer into the surface. Then I use an impact wrench (mine is battery powered, OLD Dewalt) so that I can make that expansion wedge hit reliably. I have several times been able to screw one of these out using a hand powered ratchet or wrench but the electric impact has never had that happen. Some still catch sooner than others so the exposed part of the bolts are different depths...c'est la vie.

 

[redneckbmxer24]

The plastic is a bad move, it’s going to do nothing but hold moisture against the bottom of the safe and potentially cause rust. The concrete is porous and will breath.

Not to mention mention a sawzall will go through it like butter and all you’re doing is giving someone the perfect gap to run a sawzall around it and cut the anchor bolts.

 

[Aftermath]

The plastic is a bad move, it’s going to do nothing but hold moisture against the bottom of the safe and potentially cause rust. The concrete is porous and will breath.

Not to mention mention a sawzall will go through it like butter and all you’re doing is giving someone the perfect gap to run a sawzall around it and cut the anchor bolts.

Concrete, while MOST is porous, it isn't very porous at all. Dams are made with it. Concrete will cure for 10 years minimum and trap moisture all by itself. I have moved safes installed on concrete poured 20 and even 40 years before the safe was "installed". Safes in place 5 years in a temperature controlled environment, on bare concrete and on carpet (the thin stuff, not like with a pad you would find in the living room), will be rusted on the bottom. Some were real bad, the ones on concrete, one so bad the guy decided to sell it for what he could and buy a new one. I talked him into asking his house buyer to just buy it rather than move it. Some of that rust isn't actually rust as we normally think but a combination of water created rust and chemical reaction to the concrete.

A piece of any vapor barrier will most definitely reduce that reaction, whether that be tar paper, plastic, Line-X or painted wood.

The base I built, after moving quite a few safes and seeing what happens, has ventilation holes drilled. When I moved from ID to OK, my safe had been in place for about 12 years. No rust. It's been in it's new place for about 2 years but I'm not going to move it just to see if there is any corrosion going on.

I don't worry about bolting it down as that is a false security for certain. Weight and safe construction are where the game is won.

 

[Hecouldgoalltheway]

High strength ready mix should do just fine, dont get it too wet, like a moderate porridge. I never hurts to roughen up the existing slab and or use a bonding agent, but with the rebar inserts and weight of a 30"x40" slab its not going anywhere. If you just have to, use a grinder and cut 1/2" grooves but not too close to the edges. Tap the edges of your form so te mud will settle and not leave voids on the edges.

Let it cure for at least a week as it takes 30 days to dry about 80%. IIRC Be sure to have a steel or magnesium trowel for finishing the surface.

This response is perfect. This man must have decades of concrete experience. If i hadn't read this, my response would have been almost verbatim..

 

[Maggot]

Either way...a 4" angle grinder gets me in your Fort Knox safe in under an hour.


View attachment 8725524

Thats the bottom line, and likey well under an hour.

 

[doubloon]

Thats the bottom line, and likey well under an hour.

instructional videos exist. Back and sides are the best attack surfaces because almost everybody makes the front thicker.

 

[chevy_man]

That's OK. I missed the part where making the bottom of a bucket thicker helps prevent it from flooding. But I don't know a lot about concrete and even less about basements.

6" rise from the rest of the floor, so it'll take at least that much water to get into the safe. Plus, he's got a floor drain. So 6" will buy him a lot of time, and insurance coverage.

 

[Fig]

Fuck. There are a lot of foremen on this job!

 

[Mike Casselton]

Hey, we get paid to offer advice and judge people, not work.

 

[Ronws]

@ClangClang

Others beat me to it but you have come to exactly the right place. If there is one thing a bunch of sharpshooters are good at, it is working with concrete. And bench presses.

And bow kills.

 

[hollowoutadime]

He's not placing cc of concrete....hes placing cubic feet, because AMERICA!!!!

Here's an approx 30" square pad pad poured for a steel column to support triple LVL's for a second floor.

I had to cut through the basement slab to excavate it. It's 16" deep, so about 22 -24 60# bags.

It's very similar to what you're doing.

Here's about 1100 bags poured under my brick - surfaced gun range

Here's a front porch supported by a footer and poured walls and deck, sitting next to brick veneered poured walkway.
Probably another 900-1000 bags.

You can rock a safe from ground to a 2" wood box. from that to a 4" wood box, etc till you get your desired height.
Did that before I installed a vault door.

 

[doubloon]

6" rise from the rest of the floor, so it'll take at least that much water to get into the safe. Plus, he's got a floor drain. So 6" will buy him a lot of time, and insurance coverage.

Yeah, I read the original post wrong. Thought he was adding 6 inches of concrete to the whole basement. Doh!

 

[ClangClang]

Here's an approx 30" square pad pad poured for a steel column to support triple LVL's for a second floor.

I had to cut through the basement slab to excavate it. It's 16" deep, so about 22 -24 60# bags.

It's very similar to what you're doing.


Here's a front porch supported by a footer and poured walls and deck, sitting next to brick veneered poured walkway.
Probably another 900-1000 bags.

This guy concretes. You probably have a bunch of bow kills too.

 

[Sean the Nailer]

This topic, to one extent or another, has been talked about, hashed, re-hashed, and re-resuscitated so many times over the years. Decades even. From many different tangents and perspectives. There are eleventy different "right" ways to do things, and at the same time there are eleventy different "don't-ever-do-this" type of things, because 'reasons'.

Let me add this one little simple point enter the discussion, and do with it what you will:

Where do you store your powder and ammo? WITH your prized possessions, to prevent theft/unauthorized contact and to keep them away from heat/fire OR/
Away from your prized possessions, to keep them away from your prized possessions in case of fire?

Now tell me, does THAT change your question and perspective?

 

[GreenGO Juan]

It will just be the concrete pad plus a 1/4" sheet of solid HDPE on top as a moisture barrier.

Seal the cement with epoxy and that should control moisture wicking.

My stats.

315 LBS
Years
Multiple

 

[hollowoutadime]

Re: powder storage/SeanDaNailer.

Since You're supposed to keep firearms, powder, and primers separate. Further, explosive items shouldn't be confined in something like a heavy walled safe. Worst case, rapidly expanding gasses need to be able to safely expand. As I didn't want to get incinerated if there were to be a fire, I moved the bulk of my powder and primers out of my residential reloading room into the barn (cool dry place).

Since the barn is has been remodeled/updated and holds all the toys of a mini-farm, I had plans drawn up to move all flammable material out of the barn into an out of the way "Dynamite shack", where I'll keep powder/primers/gasoline/diesel/propane etc into it's own home.

Being zoned rural, I'll probably expand this from the approved plans to 12'x12' and begin excavation this fall. Yes, it will have a concrete pad. I'll see that it has proper ventilation.

 

[wvfarrier]

When I did mine we drilled some long concrete bolts into the existing slab and left about 4" extended above the pad to secure the new pad. It has worked great, its been 15 years and is still rock solid.

 

[GreenGO Juan]

Re: powder storage/SeanDaNailer.

Since You're supposed to keep firearms, powder, and primers separate. Further, explosive items shouldn't be confined in something like a heavy walled safe. Worst case, rapidly expanding gasses need to be able to safely expand. As I didn't want to get incinerated if there were to be a fire, I moved the bulk of my powder and primers out of my residential reloading room into the barn (cool dry place).

Since the barn is has been remodeled/updated and holds all the toys of a mini-farm, I had plans drawn up to move all flammable material out of the barn into an out of the way "Dynamite shack", where I'll keep powder/primers/gasoline/diesel/propane etc into it's own home.

Being zoned rural, I'll probably expand this from the approved plans to 12'x12' and begin excavation this fall. Yes, it will have a concrete pad. I'll see that it has proper ventilation.

View attachment 8726217

don't forget a footer.

 

[Sean the Nailer]

Mister Hollow,
I'll bet there aren't many who do what you're doing.

I'd also bet that because of the higher likelihood of b/e than fire, most store ammo and/or components in close proximity to their 'precious metals' and such.