"Does anyone have any information on how much force is required to pull a drywall screw out of a plastic strut in an ICF form? I have a local building inspector who has nothing better to do than ask dumb questions!”
Here are some common answers to this question:
Here are some capacities attributed to the FORMTECH ICF system with various fasteners being used:
Type "S" Fine Thread Drywall Screw: Maximum load 268.1 Lbs Type "W" Coarse Thread Drywall Screw: Maximum load 287.3 lbs This system uses a "virgin" plastic granule. If you want anymore information, visit their website. I hope this helps.
The first answer is probably the best answer. But what do those values mean to you as the builder or potential homeowner? Are these pull-out values enough to hold your kitchen cabinets to the wall after they are fully loaded with dishes etc.?
The first part of the second answer was pretty realistic of what happens in the field. The reason the ties get stripped out by installers is because they are rarely informed on how to install the screws into the plastic ties. So, just how strong is the connection to the wall when you are relying on the installer to know what to do?
The idea that you ought to build your own demonstration device for testing the screw pull-out values is beyond belief! First off, the building official is not qualified to accept a crude test such as a homemade mock up like this. All testing of building materials and processes are to be carried out by code-recognized testing labs that have accreditation and the ability to carry out such testing without bias or other concern. Don’t waste your time developing a testing program. The building official is just doing the job they were tasked with, which is to preserve life, health and safety. Most of all, if the building official accepts a test procedure like this, what else would he/she accept that may not be accurate? Ask the form system manufacturer for the data.
The third answer was going good, but once again, the focus was lost. The fact that the material is virgin or regrind plays a very limited role when it comes to screw pull-out values. The main detail that leads to higher pull-out values is the overall thickness of the tie material, and the type of “plastic” that is being used. Most all of the systems with plastic ties use mixtures of different types of plastic polymers, some polymers are stronger than others, some are brittle when cold, some are “rubbery” when hot.
Ultimately, whatever material or brand of ICF that is used, the important issue to consider is whether or not it will perform for the particular application you are intending to use it in. Nearly every system on the market today has a tie that accepts a course thread screw with a pull-out value that is acceptable for hanging sheetrock. In most cases, we would suggest the use of embedded plates for hanging items such as kitchen cabinets. Ask the manufacturers for the numbers and while you are at it, ask them for comparisons of their product to wood and metal frame.