Who in his right mind would ever argue that a "typical" ICF house (presumably meaning one with no deck protection) would be "safer" than a storm cellar? Obviously, a buried reinforced concrete structure is at least as safe as a surface structure of the same materials. We seem to be making extremely broad statements that really don't get to the point of the original question that I challenged, which was that it was impractical to build an attractive home with ICF walls that would be "safe" from an EF5 tornado. And, frankly, all of the questions are affected by what people are willing to buy. I maintain that it IS practical to build an ICF home, including an insulated concrete deck (using InsulDeck or LiteDeck, for example), that also contains a fully-enclosed ICF safe room, without it "looking like a bunker, that no one would buy." This Reward Walls posting includes a couple links to more recent examples of ICF walls surviving the Oklahoma EF5 tornadoes:

"Reward posted two homes to their Facebook page yesterday. Both homes took a direct hit and as you can see, sustained substantial damage - BUT, the owners were safe and the walls stayed true. It was the windows, doors and roof that failed. It is interesting to note the projectiles stuck in the wall, but nothing was able to pass thru. You can also see the damage of the wood frame homes that were the neighbors.

https://www.facebook.com/media/set/...976&type=1

https://www.facebook.com/media/set/...976&type=1

A concrete roof deck that creates an envelope combined with projectile resistant windows (like those that are required in Florida) would have substantially minimized the damage to either of these homes."

I can assure you that both these homeowners (who rode out the storm in their ICF safe rooms) are extremely happy right now that they had built with ICF. Note that the caption above the images quotes their energy savings to be in the 50% range. An insulated concrete deck would have definitely INCREASED those energy savings, and their would definitely HAVE BEEN a recovery of their costs for the decks.

Coincidentally, if the hdpe fastening strips in the remaining ICF walls (shown in these images) are intact, then there is no reason the exterior veneer can't be simply replaced in these two homes. They look to be in pretty good shape to me. I plan to make further inquiries, because I think this is a pretty important opportunity.

So, the question is not: "is ICF safer than a storm cellar" the question SHOULD be: does the total ICF/reinforced concrete concept make a better overall choice, including cost, storm safety, energy savings, interior air quality, comfort, etc. And would the ICF/concrete deck home with a safe room be safe enough: I submit that it would be. That's what I was "saying."

t seems you will likely be in your house this winter

I was already "in" it last winter. Never mind that the front door is 100 sf of plastic sheet or that the 10" range duct and the 6" pizza oven flue were open to the outside, but we never put more than 18KBTU into it at near design temps. We calculated 28K - 32K BTU after solar effects, so something is happening, but it is very difficult to say what it is. I know the air sealing is very good. Better passive performance than expected?

Once the outside temps got higher than the low 40's, we turned the heat off and it stayed comfy.

dmaceld - sure wish there was a way of know what the actual efficiency of your heat pump at -9 is. Also what the efficiency of your "plenum" is.

You have a single storey 2000 sq. ft. plus the loss from your crawlspace plenum rated at 3000 btu's and you can't keep up at design.

I have 1400 of basement, about a third is walkout. The main floor is also 1400 which includes a turret that is about 2/3 windows (wall space ratio). Second storey is also 1400 complete with turret in master.

1000 feet of garage which is kept at about 65 sometimes higher (its my workshop till I finish the trim and some more cabinets). There is 700 square ft of suite over the garage that is connected by a doorway to the second floor. The garage shares most of one wall with the house. The garage has two 9 x 8 overhead doors.

So about 5900 square feet. Plus a considerable stack effect. Inside temps are around 73ºf and design is -25ºf.

House was run on Wright soft using R50 for all ICF and actuals for all others. House has a lot of windows but they too were taken at actual values. Results called for just over 52000 btus not including makeup.
There is just two of us living in the house. Most lighting is cf and down to one fridge. Do produce a bit of heat in my office. One computer that is on all the time and several printers and other peripherals. Do custom design on Power CAdd so the computer does run warm when I'm in.

I now heat with a 50,000 btu boiler and have no problems at design.

Heat load calculations generally ignore the heat generated by daily living

Ha Ha. Right now, most heating contractors seem to ignore the heat load calculations themselves. One contractor tried to spec TWIN 90K BTU gas furnaces for my place, probably based on square footage alone. Others were at 65K, 90K, 105K......Reality is probably more like 30K or less.

As these houses are built better and better, the ancillary heat inputs are going to become more and more important to keep from oversizing your heating plant. And, in mild climates, more attention will need to be paid to cooling strategies in the warmer months.

My brother installed a 2 x 6 frame manufactured home

Know anything about the construction details of that home?

Posted By dmaceld on 01 Jun 2013 10:47 PM

All I can say is I'm glad I didn't use R50 for my heating/cooling calculations. My nephew did them using Wrightsoft with 6" ICF wall construction selected in the program. For my one story, 2000 sq ft house w/ crawl space and roof insulation on the underside of the deck, the heat load came out just over 30,000 Btuh with 74F inside, 9F outside. My Daiken heat pump kept the house at 72F when the outdoor temp hovered around -9F to 0F for more than a week. At that temp the heat pump output is only about 20,000 Btuh. It ran constantly. The 10,000+ Btuh deficiency was made up by the normal heat of living, i.e., TV, computer, cooking, bodies, etc., plus a day or two of running the pellet stove at low output.

Heat load calculations generally ignore the heat generated by daily living, which can be a substantial portion of the heat supply in an ICF house, or for that matter any well insulated house. Be sure to factor that into your assessment of how low the apparent heat load is on your ICF house.

In my case daytime solar insolation is a major contributor to the heat supply, not just through the windows but also through the 10" of roof foam insulation. When the day is cloudy in the winter the heat pump runs a lot more hours.

Now, as a contrast let me share something about a stick house. My brother installed a 2 x 6 frame manufactured home on our family farmstead which he owns. This is used as a guest house for his children and their friends. Last week, when the temp was in the 40's there were about 8 people in the house. They had the windows open to cool the place down. This isn't the first time I've seen that. That house is so tight and well insulated that a half-dozen or so adults produce enough heat to keep it warm without running the furnace, even in cool spring and fall weather.

As per the studies conducted, the whole thermal mass comes down to location, location, location. ICF's thermal mass benefit in Arizona and the thermal mass benefit in New York are night and day. It's all about diurnal swings during a 24 hour period. Although that is another topic for another thread.

As far as the 8 people in the home. Each adult is worth about 1,000 BTU's or even up to 2,000 BTU's when active. So with 8 people that's easily 8,000 - 16,000 BTU's of heat. In the deep freeze of a Chicago winter with a lot of people inside during a family get together, it was not uncommon to have to open a window to cool off the home.  People put off a lot of heat. A 2x6 framed home can be built to be very energy efficient and some are above a true R-30 wall value.

As mentioned, one has to also factor in the windows. In summer they are usually a loss. In winter they can be a gain if properly designed through passive solar. Either way, you are looking at an R-Value of R2 or R3 for double pane windows and a R7 for a triple pane window.

Posted By ICFHybrid on 01 Jun 2013 11:26 PM

t seems you will likely be in your house this winter

I was already "in" it last winter. Never mind that the front door is 100 sf of plastic sheet or that the 10" range duct and the 6" pizza oven flue were open to the outside, but we never put more than 18KBTU into it at near design temps. We calculated 28K - 32K BTU after solar effects, so something is happening, but it is very difficult to say what it is. I know the air sealing is very good. Better passive performance than expected?

Once the outside temps got higher than the low 40's, we turned the heat off and it stayed comfy.

I'm thinking maybe there was a smile on your face as you were typing that!!

Installing the front door and dealing with the flues could conceivably drop that to 14-16,000. R-23 to R50. 28 - 32 to 14 or 16. Yeah, I think your numbers make the case.
I agree that it difficult to say with certainty but if we allow the nay sayers to continue to say R23 and don't come up with better testing and modelling scenarios we are unlikely to come up with the answer.

If you read my last post you will see that my house performs better than R50 and was not "designed" as solar although the turret does pick up some. I can't remember where you were building so I'm not sure what your design temp is.

Posted By Lbear on 01 Jun 2013 11:51 PM

As per the studies conducted, the whole thermal mass comes down to location, location, location. ICF's thermal mass benefit in Arizona and the thermal mass benefit in New York are night and day. It's all about diurnal swings during a 24 hour period.

I beg to differ. Calgary's clime is somewhat colder than New York but the mass in my ICF's make it perform at double what should be expected. There might be a difference in how you deal with the mass but I think conventional thinking on that is wrong as well.

Posted By okicfpro on 01 Jun 2013 11:17 PM

"Reward posted two homes to their Facebook page yesterday. Both homes took a direct hit and as you can see, sustained substantial damage - BUT, the owners were safe and the walls stayed true. It was the windows, doors and roof that failed.

https://www.facebook.com/media/set/...976&type=1

In the photos of the damaged ICF home above, it appears that the top plate on top of the ICF wall wasn't properly secured which likely contributed to the roof leaving the home.  In one photo you can see an anchor bolt with nut sticking up out of the concrete, but no washer.  This would have allowed the wood plate to pull over the nut.  The anchor bolt behind that one doesn't even have a nut on.  It appears that the anchor bolt was set too deep and a nut was probably never installed.  It is this kind of lack of attention to detail during construction that allows many homes to fail that might otherwise survive intact.

Posted By FBBP on 01 Jun 2013 11:40 PM
dmaceld - sure wish there was a way of know what the actual efficiency of your heat pump at -9 is. Also what the efficiency of your "plenum" is.

You have a single storey 2000 sq. ft. plus the loss from your crawlspace plenum rated at 3000 btu's and you can't keep up at design

I agree, it would be nice to know what the efficiency of the HP is at -9. The capacity table in the factory engineering manual gives data down to 5.5F. The output is listed from about 28k to 27k Btuh at indoor temps from 61F to 75F. It's a 3 ton rated unit with max output near 48k at 60F outdoor temp. I graphed the data and extrapolated to get an estimate of 20 to 22k Btuh at -9F. The COP at those cold temps is still between 2 and 2.5. Daikin only rates and advertises their system down to 5F.

The HP does keep up at design temp. In fact its output may very well be less than 30k Btuh because it has a variable speed compressor and fan in the outdoor unit and is microprocessor controlled. It throttles the output to match demand. I've never heard it cycle more than once per day - on in the evening, off in the morning, both summer and winter. When demand is low you can't even tell the compressor and fan are running, they're running so slow.

My plenum is 100% efficient! That's because the air handler is in the crawl space and the entire crawl space IS the supply plenum! Gives me a quasi radiant heated floor in the winter which is sure nice. We have no cold spots or hot spots or drafts in this house.

The fact remains that the heat load calc was 30k Btuh at +9F, but the HP kept the house warm at -9F with only about 20k output plus ancillary heat. I maintain that, given the inherent uncertainty in heat load calcs caused by actual living patterns, the load of this house matches the calculation very well.

Posted By ICFHybrid on 01 Jun 2013 11:42 PM

My brother installed a 2 x 6 frame manufactured home

Know anything about the construction details of that home?

All I know is that in the past 10 years or so manufactured houses are better built than on-site stick houses are. Everything is square, glued, and sealed. Another brother, who worked in the manufactured housing industry for several years, said a while back, "One thing manufactured home owners do not complain about is their heating bill!" All manufactured homes for a number of years have been equipped with ventilators because they are so tight.

The single biggest difference between on-site constructed homes and manufactured homes are the steel beams under the manufactured home so they can be towed to the site.

Posted By ICFHybrid on 01 Jun 2013 11:42 PM

Heat load calculations generally ignore the heat generated by daily living

Ha Ha. Right now, most heating contractors seem to ignore the heat load calculations themselves. One contractor tried to spec TWIN 90K BTU gas furnaces for my place, probably based on square footage alone. Others were at 65K, 90K, 105K......Reality is probably more like 30K or less.

The days of getting by like that are ending. I don't know if it's the local county, the State of Idaho, or the International Energy Code that's the driver, but all requests for new home building permits here must have a formal Manual J heating/cooling load calculation submitted with the plans. My nephew does calcs for other HVAC contractors in the area.

anchor bolt with nut sticking up out of the concrete, but no washer.

See that all the time. At job sites, look in the cheap corrugated boxes that the anchor bolts come in. You will see a few bolts left over, a few nuts and a whole pile of washers. I'm pretty sure the supplier didn't mismatch the numbers that badly. They are so inconvenient to put on.

but all requests for new home building permits here must have a formal Manual J heating/cooling load calculation

Sure, but who looks over the paperwork to see if it is an accurate report on reality? I had a number of them done and they were all grossly inaccurate. One made a 30K error in one place an offsetting 30K error in another place. Others just made errors of the type that led you to believe they didn't understand anything about the inputs they were making.

I had a number of them done and they were all grossly inaccurate

But somehow every installer will claim "my Manual J's are always quite accurate. And I have done lots of houses to prove it."

Posted By jonr on 02 Jun 2013 07:18 AM

I had a number of them done and they were all grossly inaccurate

But somehow every installer will claim "my Manual J's are always quite accurate. And I have done lots of houses to prove it."

It just struck me that this comment is a very interesting contrast to the statements made by some that ICF construction is not a DIY project but must be left up to the professionals. Makes it look somewhat like the new home buyer stands a good chance of being screwed regardless of which way he goes.

Stay awake next time in your statistics class, Lbear. The Moore storm was four blocks wide and 20 miles long. Let's say four blocks amounts to a half mile and that the area under the path was 10 square miles. Oklahoma covers 70,000 square miles, so the storm hit 0.015 percent of the state.

Wake me up when FBBP plugs in his magic earth coupler.

Posted By ICFHybrid on 02 Jun 2013 02:08 AM

but all requests for new home building permits here must have a formal Manual J heating/cooling load calculation

Sure, but who looks over the paperwork to see if it is an accurate report on reality? I had a number of them done and they were all grossly inaccurate. One made a 30K error in one place an offsetting 30K error in another place. Others just made errors of the type that led you to believe they didn't understand anything about the inputs they were making.

Precisely and Manual J software is specifically designed to allow monkeys to generate professional looking analysis. Garbage in...garbage out... You are very fortunate to have the intelligence to sort the truth from the con. Most consumers are clueless because unless they purchase two identical products/services, one actually done properly and one just done professionally, they will be none the wiser. So it is always best to check credentials rather than put much merit in how many bananas have been peeled. Better yet to also become educated and always stay actively engaged with your projects instead of just faithfully believing that the professional you hired is competent. If one actually takes the time to become competent, one is more likely to be competent...whether one is a professional or a DIYer.

I can't remember where you were building so I'm not sure what your design temp is.

Pacific Northwest. It's like 15F or 19F or something like that. We get to single digits for a few hours every other year. This Winter we saw low 20's when I made those observations.

specifically designed to allow monkeys to generate professional looking analysis

Everyone loves a computer generated report. They look great. That's when I start asking questions and the lying begins..... Some of the worst ones are the office bound guys with the larger HVAC outfits and they are the ones who should know better. At least some of them must get paid a percentage of the job.............

Wow the ICf shills are in full cry....

The statement you challenged, okicfpro, is whether one is more likely to get sucked out of a roofless ICF house than out of a storm cellar.I'm happy you've dialed down tyour sales pitch, but....

No, you don't need icf walls to get safe room .No, I didn't make up anything about siding. The first icf house posted in this thread said stay tuned to see if it can salvaged.

The other two is aren't exactly ringing endorsements. If the tornado ripped the wiring out of the conduits, it is entirely possible that the photo albums are also gone, along with that collector Fender Stratocaster and great meemaw's tea service.

Here is what the Wind Science people at Texas Tech answer the question of whether new construction can be tornado-proofed:

A: You can, but your neighbors probably would not like it in their neighborhood and you would need some of Bill Gates’s wealth to pay for it, since I doubt any conventional lender will loan money for it. The reality is that the walls, roof, windows, doors and garage doors must be missile-resistant and the connections of the structural elements must be capable of withstanding 250 mph wind pressures. Missile resistance of walls and even roofs is fairly easy to achieve with current ICF (insulating concrete form) construction, however the connections for long span roofs and tall walls to transfer the loads induced by a 250 mph wind must be 7 ½ times stronger than those routinely required by today’s codes. Then, the issue is how to protect the numerous openings (doors and windows) routinely found in a home. http://www.depts.ttu.edu/weweb/Shelters/FAQ.php

Who to believe? I usually go with the guy who is trying to sell me something.