Hello everyone! After reading through several forums, we were most impressed with the advice and knowledge found here. We're hoping to be blessed with some of that great advice now.

We survived a tornado almost 4 years ago and after this week's storms in the South, I have convinced my husband to build a storm room in our crawlspace. Our crawl space is almost all above ground and is almost 7 ft high.

We want to build a room that is roughly 7ft H x 8ft L x 6ft W on top of a poured concrete foundation. The walls will be reinforced with rebar and filled with poured concrete. We want to do this ourselves, with some aide and guidance from our neighbor who built houses years ago.

Can anyone give any estimates of time, cost, difficulty, problems, etc.? We aren't able to contract this out, the cost would be too prohibitive. Thanks in advance for the help!

 

Take a look here:

Taking Shelter from the Storm: Building a Safe Room Inside Your House

 

Thanks for responding! Those figures are approximately 5 years old and don't take into account everything we have included in our plans. I was hoping to get advice from someone in the building field in today's cost. Thanks for the link though!

 

For starters, assuming 6-in. thick concrete, you will need approximately 5.5 cubic yards. Add cost of rebar and lumber to build the forms. Include cost of access door. Determine if you can place all concrete at once, or if you will need to do in stages. This may affect the cost of ready-mixed concrete.
Good luck with your project.

 

"Safe" from what? A tornado is about the only thing a cement box will protect you from these days.

Anyway:

8x6 is aboiut the size I renember my Grandfather's A-Bomb shelter being. This is fine for a tornado or blast shelter, but for fallout purposes is well, a "hole in the basement".

 

We want the room to be built to withstand a F5 tornado, we've been looking at ideas from Texas Tech...a leader in designing tornado safe rooms.

We're trying to get a cost estimate for the crawlspace idea to compare with putting bin one of those pre-made small shelters in the garage. We just have this huge crawlspace.....we would love to utilize it and not give up garage space.

 

Im in Jackson Tennessee we were hit last night.
Destroyed Union University and many houses.

Iam looking at shelters. I have found a concrete one
that is 5'10" tall for $2450 installed. In ground with
steps down.

I found a STEEL on that is 6' inside It cost $6,800

The steel people say, that concrete will leak through.

Somebody please fill me in on which is better and why.
Is this true about concrete leaking??
David
Tennessee

 

Don't reinvent the wheel. - Go to the FEMA site (fema.gov?).

They have tested materials and come up with the requirements for a "safe cell". This includes protection from both debris and anchorage to resist wind. The designs can be used above grade within conventional home construction or in basements. The projectile criteria is a 12' - 2x4 shot out of an air cannon at about 150 mph.

The general construction is either reinforced concrete or reinforced concrete masonry. There are guidelines on sizes, depending on whether the main risk is hurricanes or tornadoes since the ocupation period is different.

Everything is practical and well thought out from the direction of the door swings, door hardware, ventilation, roof construction (concrete) and anchorage/weight of footings.

Most of this was available quite a few years ago.

Currently, many safe cells in new construction are incorporated as bathrooms or as closets to minimize the the additional area requirements.

Dick

 

Question IS...
Will the concrete inside walls really leak after the years.
Can you seal the inside and outside to prevent that?

 

My mother has a outside concrete storm shelter in her yard and every spring it gets about a foot of water in the bottom from water seeping through. I guess it really depends on the location but I would DEFINATELY put a mostiure barrier/liner in first if I were going to install a concrete shelter that is below ground surface. Good Luck.

 

The safe cell concept was created to provide a safe area within a structure.

It you chose to have it set in the soil, you just have to build properly and use the normal construction practices to make it moisture resistant. If you chose to set it out in the backyard like to old "bomb shelters" that people expected to spend weeks in.

For a below grade application construction details are important and you must have some waterproofing or getting rid of the water that natural is due to conditions and poor drainage. This just takes some planning and good construction.

fatdaddy - you can build and seal properly if you start correctly. The design is for protection purposes, not creature comfort if it is free-standing.

If it is a hole in the ground for a once in a while tornado you may have to expect some moisture for and hour or so. - Dorothy and Toto would not have minded, just as the people in this week's storms would if they had a choice.

The concept of a safe cell is to provide a safe area that can be incorporated into construction without the waste and expense of spending money on a single purpose hole in the back yard that is rarely required and not easily accessible. If you chose, you can build a free standing safe cell above grade and disguise it as an outhouse.

 

Ideal place is to have put it in the garage pad or the shop pad I built last year.

 

If you look at the FEMA site, or think about it, it is very difficult or impossible to rely on an attachment to an existing slab. FEMA has foundation requirements. The wind and uplift from a tornado hit is too great fot a few shallow dowels/anchor bolts or a lightly reinforced slab. - That is why anything above grade in normal, good construction is usually gone.

You need a thick footing plus ties to something substantial unless you have a relatively large safe cell with a foundation. Reinforced block or concrete homes work well, but the windows and roof are worthless.

Keep in mind that there is a big difference between the winds, forces and projectiles/debris from a tornado (150 to 300 mph) than a puny hurricane (150 or less). Hurricane damage is usually to peeled roofs and storm surge, while tornados are demolition or projectiles, although near misses are like hurricanes without the storm surge.

Dick