I am in the planning stage for building a cottage. My existing cottage will be torn down and a new one built to replace it on the same site. The basement will be made using ICF (currently no basement or reliable foundation exists). The decision that I need to make is whether to continue with the ICF for the upper two floors to the roof or to build the upper two floors with traditional wood framing.

I have read lots of articles promoting ICF as a building material, but written mostly by the manufacturers. I would like to get some "real world" feedback from builders or home owners that live in (or build) foundation to roof ICF homes, preferably in a similar climate to my own.  It seems that a lot of the advantages of ICF are realized further South, but what about up here in Ontario?

I am building a cottage in Zone 5 (Ontario). The cottage is adjacent to a lake with a lot of tree coverage.

On the plus side for ICF I like the idea of a quick installation (by a qualified professional). Given the choice I would like to have this structure built quickly.

The other thing that I really like is the solidness of the concrete walls. We have endless problems with small rodents tunneling through the existing 2x4 walls. They chew up the insulation and leave it in clumps for nests. In some cases the mice/chipmunks completely remove chunks of insulation. The insulating capabilities of my existing walls must be almost non-existent by this point in time.

Heating will be a combination of wood stove and forced air propane furnace.  We have electrical service but no gas lines to the cottage. 

I am restricted to using the EXACT same foot print as the existing cottage so there are some limitations as to what can be done regarding passive solar heating and my architect is addressing that.

The expected usage model will be continuous occupation during the Summer and Fall months and then only on weekends every two or three weeks during the Winter, so the cottage will remain empty for a stretch of 2 to 3 weeks at a time over the Winter. I expect to never completely close down the cottage. When we are not present I will maintain the furnace at 7 Celsius during the Winter just to ensure that the pipes don't freeze and the place doesn't become an ice-cube when we are away. At some point in time in the future I expect to live there year round.

My biggest concerns are;

1) What would be the relative difference in cost of heating the ICF during the Winter versus wood frame construction (ie 2x6 with Styrofoam sheathing outside or double stud 2x4 walls).  How easy is an ICF home to heat?
 
2) Given that the concrete has a high thermal mass, if we are away for 3 weeks (with temp left at 7 Celsius) how long would it take to warm the cottage back up to a comfortable level? Say 20 Celsius.

3) What does it "feel" like living in a concreate block?  Whats the level of comfort? Is it comfortable? Are you always cool and damp? Are there any drafts? Is it toasty warm in the Winter?  What about summers, does it get hot inside?

I would love to hear from homeowners that have ICF from foundation to roof that live in similar climate conditions (zone 5).  The cottage will be near Huntsville in Ontario.  Do you realize any benefits from ICF or it is a disadvantage for our climate zone?

What do you recommend;  ICF or wood and why? 
Are there any ICF home owners out there that can comment. Was it a mistake? Do you like it? Was it the best thing you ever did?

Thanks, Kelly

Kelly;

You will find first and foremost much much cheaper energy costs, especially in the winter if you are away for 2-3 weeks at a time. The thermal mass of the walls do not allow the inside heat to escape, keep in mind you must be prepared to do the roof insulation properly as well. I built a cottage just outside of Huntsville many years ago(2003), the people wished we had of gone to the roof line.

The rodent problem is gone with ICF, provided you seal it up properly, this means proper waterproofing below grade, proper finishing above grade and parge coat the small area left between (usually 2" +/- below grade to 6" +/- above grade).

When I lived in Barrie, my house was standard stick frame and CMU foundation, roughly 6000 sq.ft. main floor and basement fully finished my gas bill at the end of the year was $ 1500.00 and I had the furnace only on natural gas, on the lot next door to me I built my friends house, roughly 5600 sq.ft. main floor and finished basement his gas bill at the end of the year was just under $ 600.00 and he had furnace, hot water, 2 fireplaces, BBQ and range. I think this speaks for itself. Now you are using propane which I believe is not as efficient or as good a heat if that makes sense, but you should still be further ahead with ICF over stick frame.

The quiet and comfort of an ICF home is second to none, you will still hear outside noises...it's coming thru windows and doors (they're not sound proof) but the overall quietness is much more noticeable then a stick frame home, you don't hear the high winds blowing as much since the sound is barely traveling thru the walls.

You are not going to feel cool and dampness like a typical basement as the concrete is covered with the ICF. The only drafts are where someone may have missed sealing a penetration, such as a windows and doors.

Air tightness comes first, then R value, but both trump thel value of the concrete mass from a thermal point of view. Anything you build should be able to meet R2000 standards for air-tightness (1.5ACH/50) if you want it to be energy efficient. While it's easier to make it air-tight with ICF than with stick built, it's not even close to assured with either (same goes for SIPs). Defining & detailing the primary air barrier in a stick built design is neither hard nor expensive, but it's not often done. You can't hit R-2000 levels of tightness without it though.

But an R22 stick built (whole-wall value, not center cavity) will outperform an R20 ICF in an Ontario, all else being equal- and critically, being equally air-tight. An example of ~R22 stick-built is 2x6 with dense-packed cellulose cavity fill + 1.5" of iso or XPS on the exterior. Standard 2x6 stick-built batt-insulated without foam rarely exceeds R14, and is often subtantially less given how difficult it is to get perfect-fill with batts, no gaps or compressions. And when air-sealing isn't taken very seriously air leakage in typical stick-built is more than 5x the R-2000 standard. In ICF construction it might be only 3-4x R-2000, but at that point air leakage is still a significant fraction of the heating bill. Whatever you build, if you don't pressure test it as soon as the shell is tight and the windows & doors installed you may not find out until it's too late to remediate cheaply.

Much is made of the value of the concrete's thermal mass moderating the heat gain loss through the walls, but with walls at R20 & above a far greater fraction of the heat gain/loss will be through windows & doors than through the walls & roof, and the mass in the wall is isolated from the conditioned space by at least R8 in even the most-minimal ICF, which means it does nothing to moderate temp from those other gains & losses. To get the most out of high-mass construction, the mass need to be fully within the conditioned space. Modeled correctly it's easy to see that going to concrete/stone/ceramic-tile floor and heavier gypsum board throughout (including interior walls) it's easy to exceed the mass-benefit of ICF construction from a thermal-moderation point of view.

There no disadvantage to ICF in an Ontario climate, and even if it's only buying you low single-digit percentage energy savings over a low-mass building of equal R, ICF is far stronger than most alternatives, and quieter too. Done right they just plain FEEL right- solid, quiet, Chris has it right- you can barely hear the wind in the trees, but that would also be true of double-studwall cellulose-fill R30+ walls. In hurricane-prone areas such as the southeastern coastal US the structural aspects alone can rationalize any uptick in cost, but that's not at issue here.

But R22 is well below the long term cost-effectiveness threshold for this climate. Done in a most-economical way R30+ has a rationale, and the more expensive your heating fuel, there may be room for even more. (Propane is only going to get pricier- resistance electric is even cheaper in some parts of Ontario.) For a rough judgment of what's long-term cost-effective, see table 2, p10:

http://www.buildingscience.com/documents/reports/rr-1005-building-america-high-r-value-high-performance-residential-buildings-all-climate-zones

Your climate is roughly the cool edge of US zone 5 / warm edge of zone 6. see:

http://www.architecture.uwaterloo.ca/faculty_projects/terri/carbon-aia/images/climate_zones.jpg

An R30+ stick built wall is 2x6 w/cellulose cavity fill + 3" of exterior iso, (or 3.5-4" of XPS). If you go that route you'll have to either use non-wood fiberboard structural sheathing, or argue with the inspectors about not-using interior poly as a vapor retarder, but you really can't get away with poly there, since the assembly would not otherwise be able to dry. Variable-permeance Certainteed MemBrain would work, and may satisfy the inspectors as a substitute for poly in this application. R30+ ICF can be had, but it's more than $1/R per square meter for anything over than the minimal R16-18-ish that might meet code-min. With stick built that first ~R15 is pretty cheap by comparison (under 50 cents/R per square meter) unless you're going with spray-foam cavity fill as your air-sealing scheme. Exterior foam in sheet form is comparable in installed price R for R to additional thickness on ICF, despite being cheaper f.o.b. the distributor's yard. (You waste more material on window & door cutouts than with ICF and the labor to put it up is a cost adder over the basic stick-built.)

On any moderate to high-R air-tight houses the windows & doors can make or break it. All sliding sashes and doors should be off the table- stick to fixed/casements/awnings/hoppers and only swinging doors for a more reliable air-seal. And don't even consider any with U-values over 0.30 (is that even allowed in Ontario?) Doing the math and sizing, orienting & typing the windows for passive solar gain is always worthwhile, and can be worth more than adding another R10 to the shell (up to R40 from R30) from an energy-use reduction point of view.

And don't forget to insulate the basement slab, eh? (2"/R8 EPS or 1.5" /R7.5 XPS, min.)

Chris / Dana,

Thanks for the feedback. You have given me more to consider.
I've been looking at two types of ICF; one is Nudura and the other one is Durisol. Have either of you have any experience with the Durisol product? Their website claims to be better than the Nudura style. The Durisol places the thermal mass closer to the conditioned side, but at the same time they claim low thermal bridging. After comparing the specs, I am not clear how Durisol would be superior to Nudura.

And yes, I have been talking to my architect about insulating the basement slab. Originally I was thinking of radiant heat in the slab but then discarded the idea as not really worth the extra expense. She says that radiant heat in the slab could run me an extra $10,000. Never had a home with radiant heat before, don't think I need one now. The basement will have the furnace and a fireplace so I think there should be sufficient heating down there.

Thanks,
Kelly

Kelly Where are you located. I am starting my buld next week and can come down and look if you like Paul

The cottage is South of Huntsville, I am up there on weekends. I live in Georgetown. Where are you building? I would love to see an ICF in the building stage.

Send me a PM and I will get in touch

PM me if you want to see an ICF in Toronto, with parts done in SIP. Personally I'd go with SIP above grade in Huntsville, on both performance and on price.

Victor
www.ecobuilthome.ca
A 4350sqft Cold Climate Net-Zero Intiative

I would consider geothermal (from the lake or well) and no propane. Slab on grade with a frost protected shallow foundation using a monolithic thickened edge slab. I'd consider having an air compressor connected to blow out the pipes when you aren't there - saves energy as compared to heating all the time and is more failure proof. ICFs are a durable choice although you can build to the same heat loss with wood, cellulose and foam. A little mouse poison is always helpful. Add some type of remote control to allow turning the heat on well before you get there.

Typically you need your heat exchanger 14' deep in the lake. That's the way the Fernald Preserve Visitors Center, LEED Platinum, does it in Harrison, Ohio. http://green-cincinnati.com/category/fernald-preserve-visitors-center/

Hmm... 14' of water?
The shore line is very shallow at our cottage.  It drops to about 5' fairly quickly but to get to 14' depth I would have to go approximately 150' from the shore towards the middle of the lake.

I suspect that shallower is fine as long as ice doesn't form to that depth.