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Posted: 3/9/2013 9:05:02 AM EDT
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I have read all the threads I could find in here about vault door selection and building a vault in your basement. One thing I haven't seen is fireproofing the concrete walls.
I have your standard 8" thick steel reinforced concrete walls on all sides of the vault. The roof is also 8" of the same stuff. I'm framing out the inside and planned on using 2x4's with Roxul stone wool covered with sheetrock. Basically a standard interior wall except with rock wool instead of fiberglass insulation. Recently I came across the heat transmissive properties of 3000psi concrete and it seemed like the walls would transfer a lot of heat. How insulative is 4" of rock wool? Should I worry about the 2x4's burning? Roxul spec sheets say a 4" layer passes the UL 2hr fire safety test but that UL test seems to be more about structural integrity vs temperature that will pass through. At a minimum I'd like to be able to say my vault walls, built the way I described, would keep the internal temperature of the vault below 350 degrees for a 2hr time period. Ideally I'd like it to be lower. Can someone with more experience give me a guess on how the construction I described would withstand a house fire? Also, if there are better methods/materials accessible to a common guy I'd like to know. Thanks |
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Get an old edition of the NFPA handbook, SFPE handbook, or UL Fre Resistance directory. They will document that a solid 8-inch concrete wall with rebar will do what your looking for and more based on an ASTM E119 exposure, which should bound anything involving a typical house fire.
Any penetrations in the wall or ceiling should be sealed appropriately. The door will be the least resistive portion of the barrier. |
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Thanks. You gave me the right terms to start searching for. Reading up on ASTM 119 indicates that a successful test means the average temperature on the other side of the wall didn't rise more than 250 degrees F above ambient and/or no single thermocouple was more than 325 F above ambient. There is also a cotton ignition test. 8 inch poured concrete passes the 4hr test and I can't see any reason why my house would burn that long.
I came across another interesting result. 2.75 inch concrete floors (ie 2nd story in a house) will pass the 2hr test. Ceiling tests are a little more difficult because the heat and flame are more intense. Basically it seems in a standard city limit house where the fire department will arrive and put out the fire that 8" concrete by itself is more than adequate. Maybe I'll skip the expensive rock wool and just use standard fiberglass insulation on the interior framing. It's more for the cold than anything else. |
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Well,
First off there is nothing fireproof... Then fire resistant is the name of the game... First off...if your like me at least two sides of your vault won't have any uh thermal transfer... Second, I screwed 5/8" drywall right to the cement...taped and finished... So, at this point you would have a concrete box. With a rough opening for the door... Also used 2" iron pipe for air in/out...plus two 3/4" conduits for 120v and cat6 cable Every conduit is pluged with fire putty on each end except the air intake and exhaust... So hvac yep...each ong has a manual and an automatic fire damper... Ok the door...mine came from califonia...I think... Talking to them was really good, you can make a door strong or more fire restant Ok, the door on my vault is not going away soon...in fact it was craned into its final location before the house had any lumber...just basement walls... So, I'm sure I missed something if you need to either post or email me...my vault is just getting a few final touches.. Ymmv Bret |
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Finishing the interior with gypsum board will improve the aesthetics AND overall fire resistance.
It's good defense in depth. The Gypsum Association publishes a fire resistance design manual that documents ratings associated with several cross sections. It can be downloaded free online. |
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if you are just looking to frame out the inside to make it look nice and give you straight walls, I would use tin studs spaced about 1" off the concrete. Then use a fire resistive spray foam insulation. Spacing the studs off the wall ensures the foam can get between them and form and insulative barrier. Then cover the inside with some fire rated (used for boiler rooms) sheetrock. This will give you far more thermal protection then your safe will ever be subjected to in a house fire.
As stated before, the door is going to be your weak point. Make sure it has a good expanding fire seal built into the edges. that will help the door more than anything else. |
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