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I've taken all the sheetrock off of an interior wall for some renovations we're doing. What I would like to do is use a section of that wall to create a fire resistant hidden storage compartment. It's not a safe, I don't want to spend that much money and security from thieves is not a primary concern.

My goals are:

  • Cost - cheaper than buying a standalone fire safe with similar capacity.
  • Capacity (limited depth, but height could be several feet with shelves.)
  • Camouflage (shouldn't stick out like a sore thumb.)
  • Fire protection (consider this the value to "solve for" while meeting all other requirements.)
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    Layers of type X sheetrock with staggered joints is likely the cheapest fire resistive construction, but building a door of equal resistance is not for amateurs, expensive testing is required to ensure it works properly. Just buying such a tested door is expensive.
    – bcworkz
    Commented Apr 12, 2013 at 19:53
  • How much depth do you have? It seems even trivial fire resistance would require a pretty thick walls.
    – Craig
    Commented Apr 12, 2013 at 21:26
  • Whatever your solution. You do get fire retardant sheet rock. Its designed to be non combustible for upto 45 mins in fire situations. Just something to top of your build to decrease chances of it going up in flames.
    – Ryan Walkowski
    Commented Apr 13, 2013 at 0:35

3 Answers 3

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Brick and mortar box. Put drywall over brick if you want to hide it. Leave an opening so you can take things in and out. Can use an old fire oven door or something for the opening. I actually found the best place to do this is in a closet ceiling if you have attic space above. It doesn't have to look good so don't worry about the brick job - just make sure that is is pretty well sealed so heat/smoke can't get in. Could use garden stones too.

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    Unless the building is fundamentally non-flammable, e.g., built of masonry or steel, placing a brick-and-mortar box above a ceiling in the attic space doesn't seem to be a good idea. If the structure burns, the fire-safe box will come crashing down, most likely splitting open and scattering the contents in the flames. Placing it at ground level to avoid this problem seems to make more sense.
    – Andrew P.
    Commented Dec 21, 2018 at 23:59
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If you want serious house-fire resistance most homebrew solutions will not suffice. Minimum rating should be 1-hour @ 350-degrees F, on a standard test sequence which involves external temps up to around 1750 degrees. Yes, house fires can go that high.

That will be enough protection for papers and CDs in most house fires. For magnetic and photographic media you need something rated as a media chest, which will both keep the temps down to 150F and keep the humidity in the protected area lower.

The only solutions I consider trustworthy are either a fire chest with that rating (the cheap Sentry's and similar do work) or an in-ground safe installed thru the basement floor. The latter is not a promise, just my own guess that they might work well enough.

Remember that even if they have combo lock dials, most fire chests are not safes. If you need security too, that's more expensive, bulkier, and heavier.

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    Fire safes usually work by boiling off a hydrated compound to keep temperatures low, without that capability, then a wall cavity (even if surrounded by fire resistant drywall), is just going to turn into an oven in a fire and the contents inside will be charred. Like Keshlam said, if you want fire resistance, go with a commercial, tested product. Even that is no guarantee, when my sister lost her house to a fire, the only thing remaining was the fireplace and half of a 1920's era cast iron stove, the $500 2 hour rated fire safe in the closet was completely destroyed.
    – Johnny
    Commented Jan 24, 2015 at 17:27
  • In the Great San Francisco Earthquake, documents survived in fireproof safes, only to burst into flame when the doors were opened (most weren't as fireproof as promised, an artifact of the tech of the day). That was a pretty hot fire, insulation works both ways, controlling oxygen intrusion and waiting for the interior to cool can save paper documents. Today's media storage is pretty vulnerable by comparison. And you want the fire safe in an area where it won't be covered by a heap of charcoal when the building collapses.
    – Fiasco Labs
    Commented Jan 24, 2015 at 20:53
  • @fiascolabs: in most serious fires everything not turned to ash winds up in the basement. And if the fire department was involved the basement becomes a trash-filled swimming pool. Assuming you have a basement rather than slab construction, I think that addresses the cooling off question.
    – keshlam
    Commented Jan 25, 2015 at 16:53
  • Very few basements in this area. The water table gets too high in the winter to be worth fighting it. Thanks for your insights. I can appreciate that true fire protection requires a carefully designed, thoroughly tested construction. The viability of this project was entirely uncertain, which is why I asked.
    – hemp
    Commented Jan 30, 2015 at 2:07
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I think the question is based on the assumption that most people live in cities and most house fires get put out by the local fire department after they heat up one corner of a room in the house and ruin much more with smoke damage. So if you are like most people who have decided it's just not worth buying a fire safe; you might still want to build a brick and mortar box, surrounded by two sheets of drywall. I've used a square paver stone as my lid, with drywall glued over top. No, it won't survive a devastating house fire, but it will do just fine in the other 99.99% of fires.

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  • The main idea was to hide the safe inside a wall. A brick & mortar box would be too large for that to be possible. However your point about smoke damage is well taken - if we assume the fire starts somewhere else and is put out before reaching the in-wall storage, then it doesn't need much more than a decent seal to keep smoke out, regardless of what it's made of. Though moisture prevention (fire fighting) would necessitate water resistant materials.
    – hemp
    Commented Aug 15, 2018 at 0:35

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