I am looking to put in a small storm shelter that will double as a home theatre in southern Minnesota. It will be completely below grade (2' - 3')and similar to the serious shelter down in Texas but much smaller. Rectangular  18' x 24' with 9' ceilings. One entry from existing house on long side and another at the outer corner of the short end. That one will have a below grade stairway down a small hillside leading to the back yard. Designing the stairway will be the hard part but the rest should be pretty straight forward. I do not have the soil specs yet but I wanted to run my plan past you all before it goes past the guy that gets $150 an hour. Here goes:

Footings - 12" x 24" with 4ea  #5 rebar (boxed)
Walls - 8" flat wall 
Rebar - Vertical #5 @ 16" O.C.
            Horizontal #4 16" O.C.
Floor - 4" concrete over 2" HD Extruded Polystyrene (radiant tubing installed) over 12" crushed and compacted pea stone
Drains - 4" corrugated french drains leading to daylight 
Ceiling - 10" Lite deck with a 4" slab
Doorways - 36" x 80" inswing vault type 
 
Has anyone in this forum built completely underground in a cold climate?
I understand that there are alot of variables (seismic, soil conditions, drainage, etc) but what I am looking for tips on what to avoid or look for in the planning stage. I promise that I will not bring up the vibrate or not vibrate argument like the Texas project. We'll leave that one for the ladies!

Floor - 4" concrete over 2" HD Extruded Polystyrene (radiant tubing installed) over 12" crushed and compacted pea stone

I did my second radiant slab with 4" of insulation under and I think I will do that from now on.

Are you putting an outbuilding over this storm shelter?

ICF hybrid, when doing insulation under radiant, please look at www.barrett-inc.com/creteheat.php. CreteHeat is the superior radiant slab insulation. can get R 14 with our 3 inch panel and due to its shiplap joints, no moisture peneration so no heat loss.

Thanks, but I get R-15 with the 4" and just use a simple, inexpensive 10 mil vapor barrier. It's easier placing the 4' X 8' sheets and I haven't seen any need for the shiplap joints.

I like the two exits with one going right to the outside. I'm trying to figure out how best to do this in my own plan.

For strength, I'd try to keep the doors towards the center of the walls, not at the corner.

The details on waterproofing are important especially if there is nothing above except earth. The Quad-Lock website does a good job on explaining at a high-level what one should need for membrane, etc.

Other random thoughts:
- If you want the ability to stay in that shelter for a long, long time consider splitting off a portion and use it for food storage, batteries, toilet
- Leave access channels (PVC pipe for example) to existing home to run future wiring
- Air exchanger (like manual crank in case no power and airtight room). In and out pipes for air exchange. If you want NBC capability then you need air-tightness, filtering.
- Slope instead of steps for the emergency exit could be easier and safer as long as slope doesn't get too steep
- DC LED lighting in case you want to run them on battery (most efficient)

CreteHeat comes in handy 2 foot by 4 foot panels, no need for vapor barrier, wire mesh or wire tying. It has 1 7/8 inch cogs ever 3 inch on center that the pex sits inside of. Nothing beats installation time. No joints where water can seep in. Should at least check it out.

At only 8 sq ft, your product means 4X as many panels to place as opposed to full sheets of insulation. I like the seamless vapor barrier afforded by 10 mil poly. The slab still needs reinforcement, and I like #3 rebar which presents a great place to tie the PEX.

Posted By ICFcoatings on 26 Sep 2012 10:38 AM
CreteHeat comes in handy 2 foot by 4 foot panels, no need for vapor barrier, wire mesh or wire tying. It has 1 7/8 inch cogs ever 3 inch on center that the pex sits inside of. Nothing beats installation time. No joints where water can seep in. Should at least check it out.

Code may still require a full vapor barrier under the slab in some locations, with seams overlapped & taped.  While the plastic coating is a vapor barrier, the panel seams are not gas-tight.

Sounds like you are off to a good start. My main suggestions would be:

1) Make sure you have a good engineer design (or at least approve) your wall and ceiling details. You don't want to mess those up.

2) The below slab level drains and/or sump is a must. Your foundation drain plan sounds good, especially if it will drain to daylight by gravity.

3) Put in at least a couple layers of waterproofing and one or two drainage planes that go from the top of the structure all the way down to the below slab drains. It is hard to overdo waterproofing on your roof and walls. And you will want to keep your theater/media room dry.

4) Make sure the ground over the shelter is sloped and there is no place where water could pool or puddle. Rain needs to run off quickly so that it doesn't fully saturate the soil.

5) Make sure your room is completely waterproof (several good heavy rains) before you put up any sheetrock or try to finish out anything on the inside.

6) If you are having a hard time designing the second exit, the ladder well and waterproof hatch worked fine for me.

Some great suggestions nd96. The "several good" rains is a good rule for roofing too. It's a good idea to be fully dried in before a shingle or tile goes on. Regards.

Another question I have pertains to cooling. Will I need to put in a forced air cooling run? I figure at that depth below ground and being in Minnesota I might be able to get by without one. My regular basement stays pretty cool, even in the hottest of months, so I may need a dehumidifier.

Also, where is a good source for the hand crank air pump? Might as well put one of those in.

My suggestion would be to use some type of forced air circulation. As long as you don't have too many people and an excessive amount of electronics down there, I don't know that you would need to actively cool it given your location and ground temps. You just need to make sure you are getting some fresh air circulating through, otherwise things will get stuffy. You will want to have a dehumidifier.

I used some of the figures in the link below to help me out with my decisions. My shelter will be plugged into the house HVAC. I have two 12" HDPE pipes that were installed with circulation in mind, but I think 6" pipes would have provided sufficient air exchange. It doesn't take much to condition below ground.

Ground Temps

Are you located in tornado alley?

Nice site. Valuable info.

Lbear Posted:30 Sep 2012 02:25 AM

Subject: RE: ICF Storm shelter / Home theatre

Are you located in tornado alley?


No , Minnesota is not technically considered to be part of tornado alley but they have led the nation in numbers of touchdowns many times. Our outbreaks tend to be less severe than Oklahoma and Texas storms. My cranium doesn't know the difference between a 2x4 hitting it from an EF1 tornado or a 2x4 hitting it from an EF5 tornado. I just want to be underground when any severe storm hits. I don't like that helpless feeling and I have had it plenty of times.

Posted By yayoubetcha on 30 Sep 2012 11:42 PM

No , Minnesota is not technically considered to be part of tornado alley but they have led the nation in numbers of touchdowns many times. Our outbreaks tend to be less severe than Oklahoma and Texas storms. My cranium doesn't know the difference between a 2x4 hitting it from an EF1 tornado or a 2x4 hitting it from an EF5 tornado. I just want to be underground when any severe storm hits. I don't like that helpless feeling and I have had it plenty of times.

I understand. Will the shelter have working plumbing?

If anyone is interested in a rational response to tornado risk ..... NOAA reports an average of 45/year in MN over the two decades ended 2010. Accounting for area, Minnesota at a 5.7/10,000 square miles/yr represents a smaller risk than IA (9.1) , but a greater risk than SD (4.7). Using deaths to account for severity, (2/yr in MN), getting sucked into the heavens is more likely than being killed by lightning (1.2) or shot to death by accident (0.8), but is no way comparable to dying in a fire (44) or a traffic wreck (400-plus). MN has 5.5 million residents. Tornado stats here: http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html

Finally, here is NOAA comparing tornado and hurricane risks: " Economically, tornadoes cause about a tenth as much damage per year, on average, as hurricanes. Hurricanes tend to cause much more overall destruction than tornadoes because of their much larger size, longer duration and their greater variety of ways to damage property. The destructive core in hurricanes can be tens of miles across, last many hours and damage structures through storm surge and rainfall-caused flooding, as well as from wind. Tornadoes, in contrast, tend to be a few hundred yards in diameter, last for minutes and primarily cause damage from their extreme winds." http://www.spc.noaa.gov/faq/tornado/#The%20Basics

Yards. Minutes. 5.7/10,000 square miles/year.

getting sucked into the heavens is more likely than being killed by lightning (1.2) or shot to death by accident (0.8)

OMG. More than getting accidentally shot?

Sad to say, firearm accidents are the tip of the iceberg. In Minnesota, 1,284 people died of gunshot wounds in the four-year period 1998-03.
Of those, 976 were self inflicted -- almost all suicides. But the remaining 308 represent a death rate of 77/year. In other words, a Minnesotan is 35 times more likely to be shot to death than to die in a tornado. And Minnesota is super safe compared to LA, MS and AL.

The statistics don't change the fact that the public likes the warm fuzzy feeling that they get in knowing that they have done everything possible to keep their family safe. Be that from a tornado, hurricane, earth quake, zombies, the list goes on...

What are the statistics of people that have died in the last ten years caused by the world coming to an end? Probably pretty low... Doesn't change the fact that there are thousands out there preparing for the end of the world....