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How to Build a Storm Shelter

A storm shelter is a super-strong safe room designed to withstand dangerous high winds, tornadoes and flying debris. You'll remain safe even if your house falls apart. We show you a type that you can build yourself.

By the DIY experts of The Family Handyman Magazine

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    If you have a solid concrete slab to begin with, allow about 4-6 days for construction. If you have to pour a slab or build it outside, add 2-3 more days.

How to Build a Storm Shelter

A storm shelter is a super-strong safe room designed to withstand dangerous high winds, tornadoes and flying debris. You'll remain safe even if your house falls apart. We show you a type that you can build yourself.

By the DIY experts of The Family Handyman Magazine

How a storm shelter or safe room pays off

If you live in “Tornado Alley” in the panhandle of Texas or are worried about violent storms with high velocity winds, building a storm shelter ( now called a “safe room”) should bring you a little more peace of mind. When faced with a severe storm, most people go to an interior room as you did or head for the cellar and hope for the best. Unfortunately, even those areas aren't designed to withstand extreme winds and the wind-driven debris that comes with them. A drywalled, 2x4-framed room is no match for a 2x4 traveling at 100-plus miles an hour, even if it's in the middle of a house. “Force 5” tornadoes or C5 hurricanes (the two most serious storms) can pack winds of more than 200 mph—enough to blow a well-built house right off its foundation. So a safe room can pay off, especially if you live in a vulnerable high-wind zone area. (See Fig. A, below, to find the wind zone you live in.) It won't cost a fortune, either. A little elbow grease and the building materials will all but guarantee your family's injury-free survival in any storm that comes down the pike.

Keep in mind that a safe room can be more than just a storm shelter. Within the house, the room can do double-duty as a storage room, walk-in closet, bath or pantry. Outside the house, it can function as a yard or storage shed. Wherever you put it, a bonus is that it's a virtually impregnable vault for valuables, guns, documents and expensive equipment.

Wind zone map

Figure A: Wind Zones in the United States

Although the center of the country is more susceptible to the strongest winds, all parts are subject to damaging storms.

Safe room design options

All safe-room designs, even for rooms inside the house, are engineered to provide a room that's completely independent of the house structure and bolted down to a concrete slab. In addition, the room has a tough, impact-resistant shell to protect occupants from the wind-blown debris that accounts for most storm fatalities and injuries.

A free booklet published by FEMA (Federal Emergency Management Agency) gives explicit construction information for building variations of safe rooms. It offers many designs to consider, depending on the design of your home and local building practices and materials.

We show a wood/steel design, but other equally effective designs use poured reinforced concrete, rein- forced concrete block, fiberglass and welded solid steel (you'd have to hire a contractor or buy a kit to construct these styles, however). Another option is a prebuilt one-piece steel or modular cast concrete unit that can be dropped into the ground or into a home under construction. Even if the house disintegrates around the safe room in the teeth of a tornado, you'll be snug and safe inside (but scared to death!).

Safe rooms are still embryonic in design, but the room we show below is the sturdiest, most DIY-friendly design we found. It'll fit in most basements, large garages or even outside on a separate slab, for people who live in slab-on-grade homes or mobile homes. For outside locations, build the structure as shown and add a roof and siding.

Safe room parts and design

Safe Room Design and Parts
Note: You can download this photo and enlarge it in the Additional Information below.

Key details of our design

Safe rooms can be built any size you want, as long as you build them with the specifications described in the FEMA booklet. This room measures 7 x 8 ft., but it could just as easily be 4 x 4 ft. When you're planning the size, keep in mind the available space, the number of people you expect to protect, the secondary purpose the room will serve and your budget.

The sandwich skin of the walls and ceiling has two layers of 3/4-in. plywood oriented in opposite grain directions. The plywood absorbs most of the impact of flying objects, and a layer of 14-gauge steel on the “safe side” (interior side) of the room further blocks debris. The skin can be applied to either the inside or the outside of the studs as long as the steel sheeting faces inside the room.

When possible, install the sandwiched skin on the outside surface of studs. Construction will be easier because you'll be able to run wire and install electrical boxes without cutting through steel. Plus, you'll be able to fasten an optional cosmetic layer of drywall to the plywood on the outside and to the studs on the inside. We had to install the sandwich on the inside surfaces on the two walls facing the concrete block and on the ceiling because those areas were inaccessible from the outside. On the ceiling, we glued 1x2 furring strips to the interior-mounted steel to hold the drywall screws.

A steel door mounted in a steel frame with three deadbolts located opposite heavy-duty hinges lets only people and pets into the room, not door-busting debris. Steel and plywood sheathing is fastened with either 3-in. self-tapping screws, or 3-in. deck screws driven through pilot holes spaced every 6 in. All doubled framing members are nailed to each other with 10d nails spaced every 6 in. on each side.

Full-service lumberyards either carry or will special-order all the materials you'll need to build this room, except the 14-gauge steel sheets. Look under “Steel Distributors” in the Yellow Pages or online for a local supplier.

Additional Information

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Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

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April 28, 2:47 PM [GMT -5]

We've also written a guide on how to build your own storm shelter...check it out and see how it compares: http://blog.nationalstormshelter.com/blog/bid/249442/How-to-Build-a-Storm-Shelter

March 26, 12:37 AM [GMT -5]

I thought about a strong room but was concerned about getting out if the house came down on it.

March 25, 10:16 AM [GMT -5]

For an outdoor shelter in rural settings, consider using precast reinforced concrete pipe. Design with elbows at each end. Flying debre won't go around corners. You can build into a hillside or landscape around. You can add doors, benches, emergency supplies etc. I dreamed this up for a friends former lake home in Minnesota.

March 25, 12:22 AM [GMT -5]

The only problem with this design is the door should open in rather then out. In the event your house fell down around you and blocked the door could still open it inward and get out of the room. You certainly don't want to survive the storm and then be trapped in your Safe Room.

March 24, 8:30 PM [GMT -5]

Interesting that you posted this old article again. I echo the question posted in April - why does the door open OUT? Seems like it would become very easy to get trapped inside and the very heavy construction might make it difficult to be heard by rescuers.

Also curious about ventilation - nothing about that is indicated in the article.

July 29, 2:16 PM [GMT -5]

I live in central Oklahoma, and I agree w/ Bob about F4 and F5 tornadoes. Underground is best. I see the other Side of the argument as well.

I would really like some technical opinions on the following modifications that I would make so that I can have the best of both worlds - above ground and max safety.

Gravel floor
Steel posts set 4 ft deep with concrete (what size pipe or post should I use?)
Steel cage of welded pipe instead of lumber
Bolt on the wood railings that you need for wood siding (over a metal skin)
Dig a 4 foot deep "spider hole" and bury 5 foot long section of a 6 foot diameter metal culvert. Make a hatch that has heavy duty steel mesh.

The main part of the shelter would be safe for smaller tornadoes and the posts keep it from blowing down. For the big ones, you crouch down in the spider hole. Tight fit, but there when you need it.

PS I have access to a welder and a cousin who welds professionally. Most will not. I am not suggesting that everyone do this, I just want to know if this would be a bad plan.

Thanks

June 20, 9:59 AM [GMT -5]

My mom lives in Alabama and just had an underground storm shelter installed in her backyard. She says she loves it. It even has carpeting X] They have a website if anyone's interested. www.survive-a-storm.com

June 20, 9:58 AM [GMT -5]

My mom lives in Alabama and just had an underground storm shelter installed in her backyard. She says she loves it. It even has carpeting X] They have a website if anyone's interested. www.survive-a-storm.com

JLO

April 16, 11:00 AM [GMT -5]

Question. The design appears to show the door openting OUT. If the hinges and deadbolts are secure enough, there should be no issue with the storm itself forcing the door open, whether it opens in or out. However, eventually you are going to want to exit shelter, and If it opens OUT, the door may become blocked with debris making escape impossible. Once the storm passes there may be other factors (gas leaks, water) that may necessitate a speedy exit as well. Is there a reason why it's preferable to have the door open OUT?

April 14, 10:34 PM [GMT -5]

My wife and i recently bought a manufactured home. It's a solid built place 2X6 construction, 2300sqft. I have done some reading about the safety of these homes and the dangers to them. I'm curious if one of these rooms would be worth it to build. I am thinking yes due to the fact the homes in our area are required to be secured to the ground and I was thinking if I bolted to the steal girders underneath it should be as solid as any other home. My problem is finding detailed plans on how to build one. I went to the FEMA site and I even bought a book online but they do a poor job detailing construction. Am I missing something on this page?

April 14, 10:34 PM [GMT -5]

My wife and i recently bought a manufactured home. It's a solid built place 2X6 construction, 2300sqft. I have done some reading about the safety of these homes and the dangers to them. I'm curious if one of these rooms would be worth it to build. I am thinking yes due to the fact the homes in our area are required to be secured to the ground and I was thinking if I bolted to the steal girders underneath it should be as solid as any other home. My problem is finding detailed plans on how to build one. I went to the FEMA site and I even bought a book online but they do a poor job detailing construction. Am I missing something on this page?

April 05, 10:25 AM [GMT -5]

While we do not live in Tornado alley, we do live in an area in SW Virginia that is prone to tornadoes and high wind every season. In fact, we had to go to the basement just last weekend because of a tornado warning. Our basement is semi-underground. We are built into a hill so the front area of our basement is underground about 4/5 of the way and the back is totally above ground - the sides go from underground to not of course.

When I was in the basement the other day I noticed how unsafe we still felt because if a tornado ever came from 3 out of 4 directions, we would be in bad shape as the basement is unfinished and we do not have any real cover down there.

So, I really like the idea of this safe room and have been wanting to build a room for another purpose anyway, so might as well do this.

Here are some of my concerns though.
1.) Our concrete slab floor is from 1943 and I am not sure how to test the strength of it. In any event, I do not have the funds to make a new one, so I suppose it is still better than nothing, especially since the room will be butted up against 2 walls in the basement that are about 90% underground.

2.) These plans do not discuss any ventilation options either.

3.) I would also have a question regarding any windows in the room at all. Obviously, I am not referring to regular windows, rather some very thick maybe double bullet-proof small porthole window. I ask because my wife is very very claustrophobic and while that is the least of our worries in a tornado, it is so bad that she might be reluctant to use it even in the face of a tornado. Being able to fabricate and integrate some sort of view to the outside would be beneficial in this situation.

March 31, 7:07 PM [GMT -5]

1. I Build these - it is Very hard to get Bullet Proof Fabric , and in the Correct Sizes !
2. It's pretty extensive as Far and Reinforcement in all the Proper Area's !
3. Hardwood Helps as it is so much Stronger !
4. I'll Provide a Kit - that You Assemble - Minus the Dry wall - which is Obtained Locally .


I'm at : Customwood@rochester.rr.com
Thanks
Dan

March 31, 7:04 PM [GMT -5]

Here ya go to see some of My Work !
http://s1263.photobucket.com/albums/ii637/CustomTrim201/

March 31, 6:55 PM [GMT -5]

1. I Build these - it is Very hard to get Bullet Proof Fabric , and in the Correct Sizes !
2. It's pretty extensive as Far and Reinforcement in all the Proper Area's !
3. Hardwood Helps as it is so much Stronger !
4. I'll Provide a Kit - that You Assemble - Minus the Dry wall - which is Obtained Locally .


I'm at : Customwood@rochester.rr.com
Thanks
Dan

March 31, 10:07 AM [GMT -5]

I am a mechanical engineer. I spent some time as an energy analyst studying technologies to prevent global warming. I live in PA and we just had the warmest winter I've ever seen (I've lived here for 50 years). Now spring is coming and the additional energy in the atmosphere is sure to drive more tornados and more powerful tornados. So I am almost finished by shelter, and I used this FEMA 320 design.
I am not telling anyone what to do or not do, but I have read the FEMA 320 spec's and this design seems to meet FEMA 320 specs. See Drawing No: AG-06 "Wood Frame Safe Room Plan." The graphic in this design is much easier to read and visualize than the FEMA drawings. But you should read the FEMA 320 spec carefully also.
I am just finishing building a shelter room based on this design. I don't agree with the Fire Captain (who admits he's not an engineer) that this shelter design is dangerous. I believe that this design was created by engineers and that a ton of research went into it.
I do agree that it is best to put this shelter in a basement against below ground wall. Remember that you have to have a concrete floor to secure this shelter to so it doesn't blow away. I am not sure if FEMA recommends this design for inside a house (not in a basement), but they do have other designs for the interior of a house, and for a bathroom. You'll have to read the FEMA spec's or call them. My guess is that it is better than nothing even if it's not in the basement.
It would have cost almost $10,000 to have an engineering company build this shelter. I built it for less than $1000. The most expensive component is the door, so I built my own door using the same wall material (two 3/4" plywood pieces oriented cross grained and a 14 gauge steel plate), but with an extra layer of 3/4 plywood. I reinforced the door with 2/4's, then drilled holes in the 2/4's and the door frame so I can slide 1/2 black iron pipes through them to secure the door. My door opens to the inside.
The most difficult part was drilling epoxy embedded screws into the concrete floor. You have to make sure you install the epoxy embedded screws correctly. I used 1/2" wedge type screws instead because they're easier to install. They have a tensile strength of more than 1000psi, while epoxy embedded screws recommended by FEMA have 1900 psi. But my shelter is against a wall that's underground, so it is somewhat aerodynamically protected. I can also bolt it to the wall.
I also have tools inside the shelter that will let me dig myself out if necessary.
I also used 2x6's instead of 2x4's and placed them on 12" centers.
Good luck,
Frank

March 19, 6:12 PM [GMT -5]

I personally live in Joplin and have seen what and EF 5 can do.. I am a contractor and naturally we have installed many storm shelters since. That being said If you want a cheaper alternative to paying close to $5000 for a decent storm shelter this is a better option than crawling in a craw space or sitting in a bath tub hoping for the best. If you have the money I would buy a professionally built shelter. The above ground models we install that I have seen make it through a direct hit are double wall 1/4" thick steel plate with 2"x2" square tubing forming a cage on the inside of the shelter that are 1 foot on center horizontal and vertical this shelter cost $5000 installed. However for those that cant afford a shelter like this I would take my odds in this FEMA compliant shelter any day over laying under a house bear hugging the foundation supports while the house ripped away. If you have children how would you keep them safe.. This is a great article by handyman its better than having nothing so why complain or nit pic the article..

March 19, 3:56 PM [GMT -5]

This shelter is apparently designed to be installed in a basement, i.e. below ground, not ground level or higher. There are some things I didn't see noted here:

1. The deadbolts should not be the 'keyed' type. A rescuer is not going to have the keys to let you out if you can not let yourself out. Probably should use deadbolts with levers on both sides, whether the door swings inside or out.

2. The light above is only good for everyday use. Chances are, the power will be out by the time you get to the room, so use emergency lighting along the route to the room and inside of it. They are backed up by battery and should last long enough to locate and use other light sources inside the room - you do have them in there, don't you?

3. Though the premise is for short term protection, some form of ventilation should be installed in case you are trapped inside. Perhaps a pipe/double-flange combination bolted through a side wall, with a cap on the inside. It could be used to signal rescuers, too.

4. The room could serve double-duty as storage for some emergency supplies/clothing and other critical items, safes, important papers, etc. that would be lost to the wind.

5. If below ground or in flood area, consider a small battery powered sump pump & line to outside.

6. Bolt everything inside to the walls. No loose items or shelves. There could be 'a whole lot of shaking going on.'

March 14, 5:28 PM [GMT -5]

Re Door: The FEMA 320 document indicates the door is to open into the safe room for basement constructed safe rooms
http://www.fema.gov/library/viewRecord.do?id=1536
Figure II-6 - page 38 of the PDF document - Taking Shelter from the storm.

March 11, 5:07 PM [GMT -5]

Dear Handigirl

hoping you could answer question about framing-- how far apart are the double 2x4 for wall framing?

Also can you explain in a little more detail about bolting to concrete floor?

thank you

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