First time ICF'er "Storm Shelter" project
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nd96User is Offline
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29 Nov 2011 05:23 PM
I’ve followed this forum for a couple of years, but this is my first post. First of all, I want to thank some of the regular posters who have provided me with some of the insight and knowledge I needed for my project through their posts and discussions. I also wanted to let people know about my experience and maybe provide some helpful insight to someone else considering a similar ICF project. And of course everyone likes pictures, so I’ll include a few.

To start off, I’d like to have my dream home built with ICF’s in a couple years. So, about a year ago I decided I wanted to get a little experience and build an ICF storm shelter myself. I know this was a bit of an ambitious project for someone who works in a completely different industry and who had never seen an ICF block in person until I had the full semi load delivered to my yard a few months ago. I also didn’t want to take any time off from my regular job (40-50 hours a week), because I needed to pay for this little project somehow.

What I eventually settled on in my design was about a 1200sqft storm shelter that is about 18ft below grade (to the floor) and with about 7ft of dirt on top of the structure. I wanted go extra deep to reach a fairly constant ground temperature (about 68 degrees +/- 2 degrees around here). Also, I figured I wouldn’t have to worry about hail damage if I went that deep.

I started last winter with a rough idea of what I wanted, and figured I was going to need a good engineer. I was fortunate to find an excellent engineer on this forum – Jerry. He has been an enormous help with my project from start to finish. I presented him with what I wanted, and after a couple meetings, some soil testing, and a bunch of emails, he gave me a sealed set of engineering diagrams.

I managed to get a building permit from the county for a “Storm Shelter” without having to provide any details on my project or unnecessary bureaucracy. Nobody builds basements in Texas, so it is not a basement.

I spent the spring and early summer researching what I would need to know to do this project myself and figuring/planning out the details. I also researched the different ICF blocks and manufacturers out there. The internet and Google are two great tools for this purpose. I called around a few manufacturers and was able to get what I thought was good price on the ICF forms. The sales rep I worked with (Dustin) was very helpful and enthusiastic with the sales process.

I calculated the rebar and forms I would need based on the engineer’s specs. I placed my orders for materials and spent the early and mid summer cutting and bending the 26,000 pounds of rebar I ordered. If I build another storm shelter someday, I think I’ll have the supplier pre-fab most of the pieces. It was a lot of work cutting and bending the rebar from 40ft sticks, but was worth doing at least once myself.

I had planned to break ground in early August – about the driest part of the year (and also the hottest). I figured dry was the most important factor because I didn’t want my project to turn into an 18ft deep swimming pool. I could foresee the project becoming a very big mess if we got any significant rains during the construction process. Fortunately, we remained in a drought during the project and ended up with a total of only about 3-4 inches of rain during the whole 3 month building process (from breaking ground to complete burial), and nothing more than an inch at a time.

This project took some pretty serious equipment to do the dirt work – moving about 3000 cubic yards to dig the hole, and about the same amount to bury and grade the surface afterwards. I had to hire someone with the right equipment to do this for me. This was the one part of the project where I underestimated the costs some.

It took about a week for my contractor to dig the hole, and then I got to work on the sump room and foundation. The sump room is a vertically oriented 5ft diameter HDPE pipe that goes down an additional 8ft below the floor (total of about 26ft below grade). This connects to the perimeter (French) drain that goes around the shelter, and will also come in handy when I decide to add a bathroom and other pluming inside.

I got the foundation poured without any problems, installed the perimeter drain and got to work on the fun part (the ICF walls). There was a slight learning curve as I figured out some of the smaller details of working with the blocks. The outside walls are all 12” concrete, so I had knock down forms. I was a little surprised how much time it took to put the forms together. I think I spent more time assembling the knock down blocks that I did cutting and stacking the blocks to build the walls.

As the walls got taller, I put up the bracing and walkway on the outside of the shelter. I used a modified form of some wood bracing diagrams I found on this form. I had debated for a while whether to rent real bracing or to build my own wood forms. I eventually decided on the wood bracing because I wouldn’t feel as pressured for time as I would if I were renting them by the day, and I could re-use the wood from the foundation to the roof. In the end, I feel it was probably a toss-up between the two (cost vs. labor).

The outside walls were of course all ICF, but I had decided to do some internal walls with ICF’s as well. When all the walls were up and my internal wind resistant doors (and zombie resistant as one of my brothers pointed out) were in place, I proceeded with the wall pour. Having never done or seen an ICF pour before (except for what I had seen on You Tube), there were a couple things that I learned doing the wall pour myself. First, I didn’t realize how messy it would be. I should have covered in plastic everything inside the structure that I didn’t want covered in a half inch of concrete splatter. I had some tools, doors, and other materials around that required quite a bit of clean-up after the wall pour. There is no fine control on the concrete flow coming out of the pump truck, and there was a lot of rebar sticking out of the top of the walls. Every time we moved the concrete pump hose, the concrete stream would hit rebar and splatter all over.

The second issue I ran across is that I had several “T” intersections in the walls, and I made these intersections myself by cutting the regular, straight blocks. I failed to anticipate the extra bracing I would need on the outside (top area of the “T”) and I did have a single moderate size blow out. That set us back about 20-30 minutes for cleanup and a quick re-enforcement job on the other intersections. Let me stress that the blow out was completely my fault, and not a problem with the brand of blocks I used. In fact I was very impressed with my ICF blocks. They had arrived well packaged and in excellent condition. There was good quality control throughout all the blocks and I would definitely use the same brand again.

The rest of the wall pour went without problems. After several days of cleanup, I started waterproofing the walls. I had looked at both the peel and stick and paint on waterproofing products designed for ICF’s. I did a fair amount of research and I felt it was kind of a toss-up between the two. It came down to the company that had the more responsive sales rep, and I went with a paint on product. In the end, I felt I made a good decision and would go with the paint (roll) on product again.

It might have been overkill, but in addition to the paint on waterproofing applied directly to the ICF, I added a layer of house wrap, followed by ¾ inch polystyrene insulation panels (to protect the ICF from the backfill and provide an extra drainage plane), and finally a layer of 9 mil plastic sheeting. The multiple layers of waterproofing and drainage planes and the French perimeter drain will hopefully prevent any water issues down the road. Fortunately we never ran into any ground water (even down 26ft at the bottom of the sump room) despite the fact that the structure is only about 120ft away from a pond I put in a few years ago.

Finally, I got to work on the roof. I went with the ICF decking product sold by the same manufacturer that provided the wall blocks. I followed the manufacturer’s recommendations on wood shoring, but added OSB on top of the 2x6 and 2x8 framing. I felt a little uncomfortable working with the polystyrene decking sitting on just the stick frame below and I felt it would be a little easier with some of the roof openings and a large center beam that were in the design specs.

The roof pour went without any problems. I used the same paint on waterproofing for the concrete roof and added a layer of the 9mil sheeting. After about 3 weeks we took down the internal wood scaffolding, and after the full 30 day concrete cure period I had the dirt guys cover it up.

This is not a project I would recommend to the average do-it-yourself guy out there, but it can be done. To be honest, I did have a couple people help me with the project – one of my brothers, and a local laborer with some concrete experience. But neither had any ICF experience (or had even heard of them), so I was the ICF expert on the job. I did do most of the labor myself to keep costs down and for the experience.

In a year or so I plan on putting my dream ICF house on top of the storm shelter. I’d like a good size house (about 6500-8000 sqft). Now this is more that I can build on my own, so if there are any good ICF architects / builders in the Dallas area, feel free to contact me.

There are two entrance/exits to the shelter. One is an ICF ladder well that will go to the outdoors and the other will be a spiral staircase attached to the future house. The spiral stairs will go through an additional section of the HDPE pipe sticking out of the top of the shelter.

There were a couple minor issues, but overall I think it went very well for my first ICF project. The basic structure is built, but I don’t plan on finishing / furnishing out the inside until later. I paid close attention to the costs and did some shopping around to try to make sure I was getting the best prices I could. In the end it cost about $75 a sqft to build the storm shelter (it would have been under $65 if I didn’t have to do all the dirt work). It will cost a little more to finish out the inside, but still think the total cost will be at or under $100 a sqft.

Thanks for taking the time to read about my project. And again, thank you to all the contributors on this forum and especially to my engineer - Jerry. I think it is a sign of a good engineer when he comes out to your inspect your final concrete pour, picks up a shovel and a float and helps out with the concrete pour for a couple of hours at no extra cost. Thanks also goes to my wife who watched the kids and put up with me spending most of my free time the past few months working on what she labeled my “man cave”.

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29 Nov 2011 06:05 PM
Posted By nd96 on 29 Nov 2011 05:23 PM
...

What I eventually settled on in my design was about a 1200sqft storm shelter that is about 18ft below grade (to the floor) and with about 7ft of dirt on top of the structure. I wanted go extra deep to reach a fairly constant ground temperature (about 68 degrees +/- 2 degrees around here). Also, I figured I wouldn’t have to worry about hail damage if I went that deep.


Hail damage?  How freaking big is the hail down there? 


I think you will be safe from just about anything except possibly a direct strike by a nuclear warhead or a meteorite larger than a car.

By the way, those wall braces look familiar; although, an order of magnitude heavier duty than the ones I built. 

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29 Nov 2011 07:15 PM
Very very impressive project. This is one heck of a storm shelter. I did notice your comment regarding possible interest in architects and installers I have a couple of similar sized large home projects in the DFW area in work if you would like to take a tour --- also approx 100K square foot church in Arlington if you'd like to visit and Weatherford College in Decatur. Nice work. Regards.
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29 Nov 2011 07:28 PM
What a great story. Congratulations on your bunker! Just for laughs, why don't you post some pics of the interior?
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30 Nov 2011 07:27 AM
I have heard the same complaint about the lack of control when using a boom pump.  Some measure of control can be had by attaching a ram horn to the end of the boom pump line.  A smaller diameter hose attached to a ram horn can be useful when filling thinner walls.
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30 Nov 2011 09:30 AM
How deep were the concrete beams on the overhead and how much slab went above them?

How about the wind resistant doors? Fabbed locally or internet-sourced?
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30 Nov 2011 04:11 PM
"By the way, those wall braces look familiar; although, an order of magnitude heavier duty than the ones I built."

Yep. I used your basic design and beefed it up (I had your post containing the pics bookmarked on my computer). I went with double 2x4 so that I could reuse them directly as some of the vertical supports on the decking. I also wanted to avoid any accidents, so I felt a little better with the sturdier bracing. There was a kicker with a turnbuckle on my final design for some fine tuning at the end.

Fortunately other than a few rebar scratches and some pretty nice concrete burns on my legs after the first pour, there were no real injuries. I knew concrete was an irritant, but didn't realize it would burn like that.

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"I have heard the same complaint about the lack of control when using a boom pump. Some measure of control can be had by attaching a ram horn to the end of the boom pump line. A smaller diameter hose attached to a ram horn can be useful when filling thinner walls."

I had read to use a reducer, so I made sure the pump company used it. It still felt (and it probably looked) a lot like a rodeo trying to wrestle the end of the pump line over and into the spots between the rebar. I'm sure there had to be a better way to do it. I just didn't know what it was.

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How deep were the concrete beams on the overhead and how much slab went above them? How about the wind resistant doors? Fabbed locally or internet-sourced?"

The engineer went for 12" deep concerete joists with 5 inches of slab on top of that. The larger center beam is 24 inches wide and 19.5 inches deep (with the cover).

The wind resistant doors were found on-line. They were made by a company called Homeland Safes (in California). They basically custom made them to my design / specs. They gave me a pretty good deal - I got 3 doors shipped to me for $2000 a door. A good company and I would recommend you check them out if you are shopping for something similar. I did a lot of shopping on-line. Just easier for me to do with my work schedule.

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I'll snap a few pics from inside the shelter and try to post them later this week for those interested.

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30 Nov 2011 04:52 PM
Wow, that is one insane storm shelter. Are you preparing for the end of the world or something?

I assume you live in tornado country? Even if a F5 hit you directly, you would be completely safe while underground in that thing. You trenched awfully close to your home, it seems in some pics that the home is just a mere foot from the pit. 

The amount of re-bar in that project is mind boggling. How did you eliminate voids, did you use an internal vibrating method?

What psi and slump was the concrete? Are you in the construction business, because this was not a project for the DIY guy.


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30 Nov 2011 05:24 PM
Wow, that is one insane storm shelter. Are you preparing for the end of the world or something?

I assume you live in tornado country? Even if a F5 hit you directly, you would be completely safe while underground in that thing. You trenched awfully close to your home, it seems in some pics that the home is just a mere foot from the pit.

The amount of re-bar in that project is mind boggling. How did you eliminate voids, did you use an internal vibrating method?

What psi and slump was the concrete? Are you in the construction business, because this was not a project for the DIY guy.



I live just a little north of Dallas, so we do see some good storms and tornadoes around here.

The house right next to the hole is actually a guest house that is currently being taken down to make room for the future ICF house.

I did use an internal vibrator. However, it was very difficult to reach the bottom 1/3 of the walls (over 9ft tall), through all the re-bar. I did some testing for voids afterwards and think it filled fairly well. I did about 150-200 test probes through the Styrofoam. About 1 out of every 25 test sites the probe went in a little further than the 2.5" expected. Most were within 1/4 an inch, and I only found one void that was over 1/2 an inch (actually was 7/8"). Most of the void areas were near corners. I assume the concrete didn't flow around the corners all that well. Not perfect, but overall I don't think it was too bad.

The floor concrete was 3500 and the walls and roof were 4000psi. We went for a 6" slump with each pour. Yes, a lot of re-bar, but I guess you need it that far underground.

No, I don't work in the construction industry - I actually work in the medical field. But my father was a carpenter and did work on some side-jobs with him as a kid before going off to college. I did do a heck of a lot of on-line research and planning before I started the construction process. I agree, this is not a project for the average DIY guy.

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30 Nov 2011 05:31 PM
nd96,

Your project with all of that congested rebar would have been a prime candidate for LaFarge's Agilia mix.  It flows so well that on small projects the hose would not have to be moved and vibrating may not have been needed.  In fact, this mix flows so well that the slump test actually measures spread instead of slump.  Unfortunately, the Agilia mix is not available everywhere and it costs more than regular mix but less workers are needed which may help offset the extra cost for the special mix.
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30 Nov 2011 08:05 PM
They were made by a company called Homeland Safes (in California).
Ha Ha. I thought they looked familiar. I used them for mine.
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30 Nov 2011 08:59 PM
I did use an internal vibrator. However, it was very difficult to reach the bottom 1/3 of the walls (over 9ft tall), through all the re-bar. I did some testing for voids afterwards and think it filled fairly well. I did about 150-200 test probes through the Styrofoam. About 1 out of every 25 test sites the probe went in a little further than the 2.5" expected. Most were within 1/4 an inch, and I only found one void that was over 1/2 an inch (actually was 7/8"). Most of the void areas were near corners. I assume the concrete didn't flow around the corners all that well. Not perfect, but overall I don't think it was too bad.

The floor concrete was 3500 and the walls and roof were 4000psi. We went for a 6" slump with each pour. Yes, a lot of re-bar, but I guess you need it that far underground.


With ICF's, vibrating the concrete is MANDATORY. There is another thread about that but studies show that it is NOT optional, vibrating is a must. Corners are NOTORIOUS for voids, that is always the worst spot for voids, yet that is where structural strength is mostly needed. Internal vibrators are the industry standard, external ones have been tested and shown that they do not work that well. Pounding on the wall with a hammer and block of wood is useless.

One cannot over vibrate a wall, that is for sure, unless it has a blow out. 




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30 Nov 2011 11:36 PM
Posted By Lbear on 30 Nov 2011 08:59 PM

With ICF's, vibrating the concrete is MANDATORY. There is another thread about that but studies show that it is NOT optional, vibrating is a must. Corners are NOTORIOUS for voids, that is always the worst spot for voids, yet that is where structural strength is mostly needed. Internal vibrators are the industry standard, external ones have been tested and shown that they do not work that well. Pounding on the wall with a hammer and block of wood is useless.

One cannot over vibrate a wall, that is for sure, unless it has a blow out. 





How many walls have you poured?
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01 Dec 2011 04:20 AM
Posted By arkie6 on 30 Nov 2011 11:36 PM

How many walls have you poured?

Your argument is not with me but with Portland Cement and the engineers who conducted scientific testing with ICF's and posted this study:

Voids Within ICF Walls


Even ICF Magazine admits that this is a valid issue with ICFs. All external vibrating methods showed significant voids within the walls.


The OP used extensive internal vibrating methods and he still encountered some minor voids.
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01 Dec 2011 05:07 AM
I'm not an expert, but I decided on the internal vibration because the general consensus from my reading pointed to that being the best method. I'm sure other methods are satisfactory in some situations - depending on the slump, amount and spacing of rebar, gravel size, and maybe half a dozen other factors. There are probably too many variables to make an absolute statement about one method or another. I just felt internal was better to use in my situation.
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01 Dec 2011 07:45 AM
Posted By Lbear on 01 Dec 2011 04:20 AM
Posted By arkie6 on 30 Nov 2011 11:36 PM

How many walls have you poured?

Your argument is not with me ...

Yes, my argument is with you.  Your post above gives the impression you have lots of experience working with concrete.  I suspect you have little or no experience with it.  You were just using a magazine article for the basis of your post, the same article that most of us have seen before.  And on top of that you hype up your post by using words like MANDATORY in all caps.  That's not stated in the article. 

And anyone that states you can't over vibrate concrete clearly doesn't have a good understanding of what they are discussing.

Most of the significant void problems in that article were due to using too low of a slump concrete.  Higher slump concrete resulted in few if any voids even with little or no vibration - see Figure 15, 21, 28, 29, and 30 as examples.


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01 Dec 2011 10:26 AM
Do most ICF installers order a mix with a slump of 6?  If so, then as much as 2" of slump can be lost passing through the pump.  Is it reasonable to assume that the slight loss of slump can increase the quantity and size of voids?  If so, then a higher inital slump should be ordered.  However, higher slumps will cost more if created by a mid or high-range admixture.  Your thoughts, please.
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01 Dec 2011 01:51 PM
Posted By arkie6 on 01 Dec 2011 07:45 AM

Yes, my argument is with you.  Your post above gives the impression you have lots of experience working with concrete.  I suspect you have little or no experience with it.  You were just using a magazine article for the basis of your post, the same article that most of us have seen before.  And on top of that you hype up your post by using words like MANDATORY in all caps.  That's not stated in the article. 

And anyone that states you can't over vibrate concrete clearly doesn't have a good understanding of what they are discussing.

Most of the significant void problems in that article were due to using too low of a slump concrete.  Higher slump concrete resulted in few if any voids even with little or no vibration - see Figure 15, 21, 28, 29, and 30 as examples.



What you are stating that you have built ICF's without performing any vibrating methods, correct?

The Portland Cement engineers stated that one can't over vibrate and the Portland Cement engineers stated that vibrating ICF's is mandatory or significant voids are to be expected, especially in corners and high re-bar areas.

The study shows what happened when NO vibration methods were being used and they ripped open the ICF forms. The amount of voids was shocking. When higher slumps were used, it weakened the concrete structure and dropped the psi rate.

The point of all of this is a discussion on ICF. The trade/designs of ICF is still not mainstream and the techniques and practices are all over the place. I am trying to educate myself to see if I would use ICF in building my home. One thing for sure, I would NOT employ an ICF contractor who does not implement vibration methods when using ICF. If an ICF contractor told me that they don't use any vibrating techniques, I would not even talk with them and find another ICF contractor. That is just my view.

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01 Dec 2011 07:28 PM
Posted By Lbear on 01 Dec 2011 01:51 PM

What you are stating that you have built ICF's without performing any vibrating methods, correct?



No, I did not state or imply that.
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01 Dec 2011 09:19 PM
If an ICF contractor told me that they don't use any vibrating techniques, I would not even talk with them and find another ICF contractor. That is just my view.
I just completed 9 pours on my ICF home. The contractor made sure a vibrator was present and tested for each pour. We used it to vibrate some regular 8" panel formed walls and we used it to vibrate a large composite beam that was 3/4 conventionally formed. That was because it had reinforcing rings every 4" on center.

The rest of the build was heavily reinforced, but the number of other places we vibrated was about 5, total and each only after a "conference" with the Number 1 and Number 2 on the job. It looks to me like they vibrated at the location where each lift began and ended and that's about it.. I have found no voids so far and we've been into a lot of places. I had ARXX block which has rounded internal corners. That may help prevent voids at those locations.

My conclusion is that if your ICF contractor is experienced enough and uses proper mix and placement technique, the need for vibrating is very, very low. Hope that helps you.
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