Our DIY ICF house in northern Illinois is nearly complete and I wanted to share some observations, positive as well as negative.

On the positive side:

1. Heating costs are 60-70% lower than our standard stick frame house (built in 1991.) I should achieve my goal of 2 BTU/sf/HDD.  Of course, ICF construction is only one factor contributing to an energy efficient building, but certainly an important one. 

2. We sealed our ceiling with closed-cell spray foam augmented with fiberglass batts to R50.  Roof snow does not melt from heat escaping into the attic.  This minimizes the buildup of ice at the eaves which can result in ice dams and damaged gutters. 

3. Winter humidity can be precisely controlled.  We set the humidistat to the desired level and the HRV operates as needed to keep it there.  Humidity is trapped in a tightly built house, so an HRV is absolutely required to keep it under control.  We found that a relative humidity of 35% keeps windows and door knobs free of condensation on the coldest winter days.

4. Air temperature throughout the house is very even, unlike our conventional framed house.  I attribute this welcome condition to the air tight construction, the thermal properties of the ICF walls, and the triple glass windows.  We have force air heating with a variable speed air handler which maintains constant air circulation at a low volume.

5. Our, as yet, unfinished basement is dry and easily maintained at 68 degrees.  The ICF walls hold in the heat and the Platon dimple membrane holds out the water.  We also insulated the basement floor with 2" XPS.  When finished, the basement will double our livable floor space.

6. Low air infiltration means excellent dust control.  House is located in corn farming country.  Dust produced by farming activities and carried by the prevailing wind is a major complaint of homeowners in the area.  Since nearly all outside air is brought into the house through the HRV where it is filtered, the accumulation of dust throughout the house is minimized.

7. Low air infiltration means excellent pollen control.  We added an electronic air filter to the stream of fresh air entering the house (thru the HRV) which removes most airborne pollen.  My hayfever symptoms disappear inside the house.

8.  Outside noise is almost completely blocked out.  This is particularly welcome on days when trash and recyclables are being collected and green space areas are being mowed.

9.  The house should stand up to an F-2 class tornado (not unheard of in this part of the country.)  I hope I never have to experience this.


On the negative side:

1.  The added cost of ICF construction and the associated energy efficient construction methods could not be completely recouped if we were to sell the house today.  We knew this up front.  Being retired and planning to stay in the house long term, we opted to spend more now in order to minimize the recurring cost of ownership (utilities, maintenance, taxes, etc.)  Time will tell if this was a wise decision.

2.  Ultra-tight (e.g., ICF) construction requires attention to air quality issues.  I mentioned humidity control already.  There is a potential for mold growth if moisture is not controlled.  Cooktop and fireplace venting must be carefully engineered (we elected to install an electric fireplace.)  Low or no VOC materials should be used in construction.


All in all, I'm happy with the result.  Despite the many positives, I don't think ICF contruction is right for everyone.  It will depend on personal needs and circumstances.  For those who decide to go the ICF route,  I think you will be pleased with the increased comfort and quality of life it affords.

Thanks for an informative report from the consumer's point of view. Do you have any idea how much more you spent going ICF versus framed construction? I'm a little concerned about the ultra-tight situation. We like the doors and windows open as long as it's between 55 and 80 outside. It would be nice to be able to button things up, though, when it's very hot or very cold outside. Our current house in FL is concrete, and the mass has a good leveling effect, tending to keep the house warmer during brief cold spells, and cooler during brief hot spells. I'm thinking the ICF will have the same effect?

Clark thats a good first hand review, thanks for posting. It's my opinion that icf is for anyone living in a tornado, hurricane or earthquake zone. If you live in other areas SIPS can be an acceptable alternative or used as a roof system with ICF. Also, To answer jdebree's question about the ultra tightness of a house. While it's true that you do need to address this issue, it doesn't mean that you can't enjoy open doors and windows. You just have to address this when planning for when your doors are closed like in the dead of winter or summer. A quality erv/hrv will take care of this and there is no need to worry about that other than routine filter changes like you should be already doing with a furnace.

Clark, If the real estate market wasnt in the crapper like it is, I think you could easily recoupe the cost of the icf. Have you looked at the insurance savings for your home owners insurance? There are savings there just FYI. Also, the reduced hvac tonage and faster build time can usually take care of the slight increase in build cost with icf, at least that has been my experience. I'm glad you like your house and enjoy your energy bills when everyone elses goes up over the next few years. :)

jdebree, you asked about the cost of building ICF vs. stick frame. I wish I could give you a definitive answer. I'm often asked that question. The assumption is usually that it costs a lot more, explaining the rarity of ICF construction in my part of the country. I kept careful cost data throughout the construction of my house. It cost about $10.50/sf for the ICF walls (basement and 1st floor) which I erected and poured myself with some hired labor. The house is 2200 sf plus that much unfinished basement. The ICF was just 6.5% of the total construction cost. All told, it cost me $145/sf to build, excluding land. That's high for an owner-builder house, but keep in mind that this is a custom built house with many extra-cost features and upgraded materials. If I had done a stick frame, I'm guessing I could have saved 3%, maybe 4% max of the total cost of construction.

Clark, Very interesting detail. I am one of those guys that believes that ICF is actually for everyone and so feel compeled to ask a question or two about the two negatives you listed. I don't see them as negatives actually. 1) Regarding recouping your cost: You reached some impressive goals as compared to typical averages for heating and cooling costs. If these numbers are close to correct your house now costs you less per month to live in than it would had you gone with stick construction. This is almost always the case with ICF coupled with a sealed attic -- the additional cost on the monthly note is more than paid for by the savings on the heating and cooling. If you paid cash for your house you may be looking at it from another perspective. If so, you may be able to explain this detail to potential buyers should you somehow deside to move out befor your payback. 2) Regarding the mention of air tight. The air tight nature is one of the main reasons that you are provided several of the positives in your list. Airtight makes hospital quality air possible in a home. If you are having humidity problems you are probably overtonned. Most ICF homes (with sealed attics) are in the neighborhood of 900 to 1100 square feet per tonne. Granted it is hard to find engineers that understand this. Also, some recommend ERV's and some do not. Just food for thought and trying to take a hard look at the negatives.

Texas, I don't disagree with you on either point. I only brought up the two last points to highlight a couple of areas that need to be considered when going ICF. Conventional wisdom is often turned on its head when building ICF, and ignoring the differences could lead to trouble.

ICF construction pays for itself, no doubt, but the breakeven point can be quite aways out. Your mortgage cost analysis seems plausible since the extra cost for ICF is amortized over the life of the loan. People typically look at their monthly cost of home ownership, not the total costs over the life of the loan. Paying cash works out a little differently because the total cost is borne up front.

I expect to save $600 - $700 each year in heating/cooling costs. At an estimated premium of $9000 for ICF over stick construction, it will take 13+ years to see a dollar return on my investment. Of course, energy costs will likely rise in the years ahead, so that figure will surely come down. As retirees, my wife and I chose to build with ICF in order to realize the many benefits ICF offers, as well as to lower our total cost of home ownership. We have no regrets as of this date. On the contrary, the results have exceeded our expectations.

BTW, I think that to achieve the same benefits with a wood frame house (were it possible), would cost as much or more than building with ICF.

Clark,
Regarding your sweat equity, you mention you laid up and poured the ICF's. Were there other items were you able to do yourself as well in that cost of $145/ft? I'm trying to understand if there might be some further drop in $/ft, depending on what other labor you were able/not able to provide. (Trying to get an estimate in my head for my own house).
Thanks for any further information

Hi Larry, I recently completed my own home with ICF and came in somewhat lower with my costs. My ICF wall costs came in at $6.50 per square foot of wall (Logix with 6.25 cavity, 10 foot walls). I could have cut a few cents off that, but upgraded to 4000 psi crete and placed steel every 16 inches rather than 32 inches. I scimped on hiring help and did the majority myself, so most of those costs were material. On the house itself, I came in at $85 sq. In my area, a comparably finished house would come in around $110 - 120 sq. Most of my savings were earned in sweat, a little blood, a broken foot and a swear word strategically placed here and there...I did all the tile, laid the wood floors, poured concrete counters in the kitchen, used "reward points" for kitchen appliances... All in all, I'm glad I built it, but I doubt I would do it again.

Dug,

As a DIY'er wishing to use icf in my future home build my hat is off to you for all your effort and it sounds like everything turned out well for you.If you don't mind my asking does your $6.50 per square foot cost include your bracing rental and pump costs ? And did you use a line pump or a pump truck? Any way i am glad  you were successful and hope you enjoy your new home.

The part about the broke foot does kind of suck though.Sounds like something i would do.

Dug,

Thanks for the information on the costs and the extent of your efforts.  That is in the range I was thinking of and similar amount of effort as well, although I'll have the roof structure, sheating, shingles done by others.  Too old to be getting up there and doing that stuff.  Especially as it'll be timbered.  So I'll Probably be in the $100-110 range? maybe?  But the $148 scared me without knowing what sweat went into his. I appreciate the information on yours. 

As I mentioned, the $145/sf includes many extra cost features and upgrades that my wife and I wanted in our retirement home.  I took a look at my cost breakdown in an attempt to breakout these extra costs (e.g., Pella Designer Series windows, radiant heat, lawn sprinkler system, induction cooktop, security system, whole house audio, central vacuum, to name just a few.)  The extras came to about $80K.  I then recalcuated my sf cost to be in the $100 - $110 range.  Even at that,  the house is well above what Means would consider "Economy" construction.   What I mean is, for that cost, I'm still getting a well-built, tightly constructed ICF house with a full insulated basement, two insulated and drywalled garages, solid 3/4" hardwood and ceramic floors, Jeld-Wen interior raised panel doors with oversized casings and base molding, 130 MPH wind resistant architectural shingles, high efficiency gas furnace, 13 SEER central A/C, etc.

I did most of work myself with very little hired labor.  I contracted out the following work: required surveys, excavation, backfill, and grading, all cement flatwork, roofing, urethane spray foam, brick and stucco finish, fascia and soffits, gutters and downspouts, lawn sodding/seeding, stairs, and countertops.  My son helped me on many rough carpentry tasks (including ICF forms installation,) electrical rough-in, and drywall hanging and finishing.  I'm retired, so I have the time to spend without interruption.  The whole project will take 22 months by the time I wrap things up in March or April.  It's a lot of work, but enjoyable and fulfilling.

BTW, my cost of $10.50/sf of wall for ICF was for TF System vertical ICF and includes all related expenses (shipping, concrete, rebar, bracing, equipment rental, pump truck, hired help for the pour, Simpson Strong Tie ledger connectors, Platon water proofing, lumber for window bucks, etc.)  I would be hard pressed to do it for less.  TF forms are somewhat more expensive than typical block products, I'm told.  I found them a breeze to put up, however, so well worth the extra cost.

I can provide further detail if anyone is interested.  I kept fairly detailed cost information.  I found it very useful to put together a detailed budget and track it on a monthly basis.  At this late date, I expect to come in 7% over my original budget.

Clark,

I appreciate the additional information.  I was hoping you sub'd a bit more out! Ha!    BTW, you made unbelievable progress to get that done in 22 months.  My hat's off to you!

Why would you need to go with an electric fireplace?  My fireplace(5 years old)  uses only outside air for combustion.  I don't know why open type fireplaces are even an option any more.

Clark,

You are my hero.

I am hoping/planning to do something very similar -EXCEPT- I won't be retired yet, so I'm expecting something more like four or five years from start to finish. But I am old enough that this is where we will live for the rest of our lives, so it will be well done, well built, well appointed. If all goes well, I hope to break ground, at least on the garage, in early 2012. A few of the items on the wish list:

-- "Cottage style" home, ~2k sq ft, open floor plan, attached garage w/ conditioned space above (where we will live during construction).
-- ICF walkout basement, with Brown County stone on exposed surfaces.
-- SIP walls on main house (garage may be stick), SIP roof.
-- I always wanted a full timber frame home, but just can't afford it. So now I'm thinking of timber frame "accents" in the living/dining space.
-- High efficiency wood gasification boiler (http://www.woodboilers.com/product-detail.aspx?id=47), plus geothermal???
-- Standing seam metal roof.
-- Radiant heat, wood floors, good doors, great kitchen, central vac.
-- Water catchment system with very large cistern.

And I plan to sub out similar tasks as you have done.

You offered further information, and I'd like to take you up on that. Being an old school engineer, I thrive on data. If you have a cleaned up (no personal information) spreadsheet or such you would be willing to share, I would so very much appreciate it. As much detail as you are willing to provide. My (new) email for this project is "builder(at)amarlow.us".

Thank you in advance for all the help, Clark. I look forward to hearing from you.

~Allen

Allen,

I'm happy to provide more cost detail for you.  Here's a high-level breakdown:

1. Indirect Construction Costs  $19,829 (6.2%)
2. Excavation & Site Work $9,736 (3.0%)
3. Masonry $75,280 (23.5%)
4. Rough Carpentry $62,093 (19.3%)
5. Plumbing $12,638 (3.9%)
6. HVAC $12,458.52 (3.9%)
7. Electrical $13,765 (4.3%)
8. Insulation $7776 (2.4%)
9. Drywall $4829 (1.5%)
10. Finish Carpentry $9,224 (2.9%)
11. Exterior Finish $33,054 (10.3%)
12. Painting $1,514 (0.5%)
13. Flooring $10,079 (3.1%)
14. Cabinets, Counters & Appliances $39,181 (12.2%)
15. Landscaping $9,561 (3.0%)

Total Cost $321,017

Here's a detailed breakdown:

Perfect.  Excellent detail.  Thank you, Clark.

Any chance you kept a journal/blog going during construction?  ie. photos and notes along the way.

Again, thanks.

~Allen

Clark, what thickness of TF ICF panels did you use?

Allen, I did keep a journal with pictures, but have not published it on the internet. I'm thinking about doing so, however.

Arkie, I used 12" forms for the foundation and 10" for the above grade walls. Those dimensions are the total width of the form.
The EPS is 2-1/2" on each side.

BTW, when I converted my Excel spreadsheet to HTML and pasted into the post, the width of the post window became
very wide. I tried unsuccessfully to fix the problem. Anybody know what went wrong?

Clark, You might try just making it an attached file. Regards.

Clark, this is an excellent level of detail. I certainly appreciate it.