I've researched some, but still have a few questions.

Somewhere on here, someone posted about secure rooms and mentioned using hardened steel mesh (expanded metal mesh) alternating with 1/2 or 3/4 inch plywood. Sheetrock on the outside surface to finish. Inside the studs, spray expanding foam insulation. When someone tries to drill or saw thru, it will slightly melt and gum up the cutting tool.

Thanks for the reply. I think I'll buy a can of Great Stuff and sacrifice a blade on my circular saw as a trial. Any idea how spray foam performs in a fire?

One thing I forgot about in my plan is ventilation. I live in a humid part of Texas and since the door will stay closed a lot, it'll be like a swamp in the closet. I'm sure I can run a small 3" duct from an existing A/C duct, but I'm not sure about needing an exhaust for the air to pass through such a small space. This also creates a weak spot in my fire protection.


 

Bump for info

5/8" sheetrock (not the lightweight crap) has a fire proof rating of 1 hour, you can double it up for extra time. Roxul insulation is fire rated and sound proof as well.

Has anyone here added sheetrock to a cheap safe to increase the fire rating?

That's basically what is in my liberty safe

Multi resident buildings require all kinds of fire resistant features such as fire resistant walls around stairwells.

This pdf addresses some solutions using sheetrock and hardi board:
http://www.jameshardie.com/homeowner/pdf/ner-405.pdf

Partition designs start on page 6.

Fire is a completely different concern but for burglary, I'd build a false shallow linen closet "interior" on a piano hinge and use one of those magnetic kitchen safety locks to keep the hidden shelf door in place.  No lock on the hollow core closet door like every other closet door in your home.  Your safe and other items could be behind that and wouldn't attract attention, as opposed to a 24" interior steel door in a hallway with a deadbolt on it.  

For fire protection, I'd look into some of the composite construction methods suggested in the other posts.  Multiple layers of 5/8 sheetrock, etc, maybe even a residential sprinkler system.

if your putting in a supply duct you need a return otherwise any moisture will only be pumped in and have no where to go.if i were doing this i would add a layer of fire treated plywood to the inside then another layer of sheetrock on all sides and the cieling.as for the door i would buy a maglock on ebay and use that instead of a deadbolt.you can get 24v ac ones and they are easy to wire.

for moisture maybe a couple 36" goldenrods by the floor  would do the trick?

If you add an A/C duct be sure to add a fire damper in the duct work so you don't compromise the fire rating.

The Station night club burned to ground and killed 100 people in ~2003, including a band member of Great White.
Cause - sparks ignited spray foam surrounding the band alcove.

Close, but it wasn't spray foam.  Think more on the lines of the cheap foam rolls that you can buy to put on your mattress.  They do have non-flammable spray foam insulation.  It is actually used as fire stop to prevent fire from spreading.  I have heard that regular great stuff foam won't burn, but I haven't tested or seen any documentation on that.

If you are on a slab, then you might want to ponder the idea of building your walls like you said with expanded metal, plywood, and drywall... and then fill the void in the wall to the top with gravel.  It would play hell with blades, it's pretty cheap, would semi-insulate. But i would only consider it if you are on a slab due to the weight.

Now, that's something I haven't thought of. I'll look into this more.

 

Put a dehumidifier in the room with a drain tube to the waste water pipes.

While it would certainly slow them down, it wouldn't take much to rip hole in bottom of wall, remove gravel from that stud-space, and continue the break-in...

For something nearly as effective but harder to bypass I would look into a sandwiched composite. The first layer would be cementicious backer board (hardiboard, Durock, etc like used underneath tile); it is a cement-like product that comes in sheets like drywall. It is heavier, but it also provides some structural rigidity. It will chew up saw-blades, although not as fast as gravel in the wall. The 2nd layer would be a layer of expanded steel mesh with thinset mudded over it in preparation for a 2nd layer of cement backer board. The combination of 2 layers of backer board with a sheet of expanded steel mesh all bonded into a solid sheet with thinset (concrete like substance used to attach tile to subfloor) would provide a VERY sturdy, cut-resistant, fire-resistant wall. The only thing you have to do after that is ensure you have enough of an insulating or active fire-proofing material (insulation or sheetrock) to provide the level of fire resistance you desire.

All other things like steel bars etc are just additional time-delaying measures.

I will say that a normal carbide wood blade on a saw will have NO issues cutting through small amounts of steel and other metals. It's the prolonged cutting or the cutting of thick or hardened metals that is going to give it a little more trouble. Afterall, the tungsten-carbide used in saw-blades is the exact same tungsten-carbide used in machining to cut hardened steels. The only difference is the cutter shape/geometery, cutter coating, and cutter speed. If the geometry, speed, or coating are "improper" it will lead to reduced cutter life but it's not an instant death-sentence to the blade.

For real cut resistance you want harder materials (to break down the cutter material) or tougher materials (so the cutter will chip/break before the item being cut). Tungsten carbide is some super hard yet very tough stuff. By that respect you need stone/rock-like materials or LOTS of steel. The harder the steel the less you need to break down the saw-blade's effectiveness. Steel rebar used for concrete is one thing that is fairly hard compared to its cost, I've seen a thread here before where the individual drilled holes ever 6" in his studs and slid full lengths of rebar into the holes to provide and relatively impenetrable barrier between the studs. While this won't stop a determined person with a good saw & blade, it will stop the sledge-hammer thief and greatly slow down the saw thief.

Years ago a friend was building one of those "check cashing" places.
The wall between the cashiers and customers was framed with 2x12s 2 layers of 3/4 plywood and 2 layers 5/8 drywall, on both sides.
The top plate was drilled out with hole saw and filled with pee gravel.
Your not kicking your way in and will stop a hand gun. (For the most part)