ICF increases the building cost between 6 and 12%. It is something that can be successfully done as a DIY project by great attention to all the details, and good, level footings (better than 1/4") are one of the essentials. Given the epidemic proportions of incompetence in the construction trades your chances of getting a good foundation are greatly increased if you hire a contractor experienced in ICF construction.(This holds true for ANY type of foundation you're installing.) I am personally at the blueprint/planning phase for a three-level (including basement) ICF house and during my research I have spoken to homeowners who have regreted using ICF for their basement- they wished they had built the entire house of ICF! It is THE WAY to build a house! (Or even just the foundation.) Very big in Florida right now. Soundproof; hurricaneproof; termiteproof; airtight; watertight; no expansion/contraction like wood frames. It forms a complete seamless envelope of a house. Its energy efficiency is much greater than a simple R-value number shows because R- value doesn't take into account the thermal mass of the concrete which buffers daily temperature swings in both summer and winter. ICF can be finished on the exterior using any finish that can be used on conventional houses. As far as strength goes, you can specify whatever tensile strength concrete you want, specify the size and quantity of rebar in the wall, specify the thickness of the wall from a choice in most ICF systems (there are, by the way, dozens of systems manufactured in Canada alone.) These stay- in-place foam forms also slow the drying rate of the concrete which increases its tensile strength (concrete continues to cure and gain strength even after a year since pour time.) Do a search on the internet- it's a great resource for info on this topic. Hope this helps in your decision, Lon. Regards, Brian.