In the past, plywood forms have had a cost advantage over insulated concrete forms as plywood provided no insulation value.
However in the 21st century, with higher energy costs, increasing global temperatures and CO2 emissions, the media and public became concerned with climate change. In 2015 the Province of BC changed the building code, requiring all foundations to have an effective thermal performance of R22. This meant that if a contractor formed his foundation with plywood, he must now build an insulated 2x6 stud wall on the inside of his foundation to achieve the required thermal performance.
The table below compares costs per vertical square foot of surface area of foundation wall in Whistler BC, Canada. Speed of form installation is from 30 to 50% faster with ICFs as there are no ties to install and no formwork stripping.
|Cost per square foot, Whistler||Plywood||ICF|
|Form cost (plywood rental cost delivered)||$1.55||$4.10|
|Labour to install and strip forms||$8.15||$5.71|
|Insulated stud wall, labour & materials, R22||$3.78||$0.00|
"I'm impressed with ICFs", confirmed Shawn. "To build and pour all the walls in this five-plex, we've spent about twenty man-days. With plywood it would have taken 35 to 40 man-days. Then to strip the forms I would have three men working two days. So I can bid this cheaper than conventional because it is so much faster."
"To get a wall truly straight with plywood is tough to do, and you can't move a wall after you pour. With ICFs and Zont Bracing you can move the wall up to 1/2" without any trouble."
Getting around the jobsite is much easier with a modified four wheel drive using this completely reversible corner block.
"To place rebar in 160' of 12' high wall would take two days for two guys", said Shawn. That is taken right out of the picture all together. It's just a super system, super time saver. From a business standpoint that's what it's all about."