Thermo-Ply Structural Panels


I've seen many builders using this product and have had the opportunity to perform numerous pre-drywall framing inspections on homes with Thermo-Ply installed.  In all cases, the panels were not installed according to manufacturer's instruction.  Blueprint details that I was able to access also revealed installation deviations from the plan requirements.  This is important as the rest of the blog post will point out.

Thermo-Ply sheathing is composed of pressure laminated plies of cellulose fibers.  In layman's terms it's a cardboard product.  Think about that for a moment.  Are you willing to pit the forces of nature in a windstorm against a cardboard 'fortified' home?  Folks in Rockwall, Texas would answer a definitive OH HELL NO to that question.  A micro-burst with estimated 100-110 mph straight-line winds blew through a Rockwall sub-division in Spring of 2017.  Damage to some of the homes was so significant that they had to be demolished.  One man almost lost his life.

There were two independent studies performed on the mid-grade 'red' Thermo-Ply panels in 2015 to verify the company's claims that it was as sturdy as 15/32" OSB structural sheathing.  The studies concluded that the product under-performed to the company's claims by as much as 23% - 39%.  The blueprint details I mentioned earlier stated a wind load rating of up to 110 mph; that is if the Thermo-Ply panels are installed correctly (on a side note; the majority of panels builders are using aren't the red, but the lower grade 'light structural' green panels).   I don't think it requires a PhD to conclude that the math is not adding up here.  Mother Nature didn't  think so either in Rockwall, Texas. 

Below are two links; one for the independent studies and the other was an assessment report after surveying the damage in Rockwall.

It is important that this product is installed according to what the manufacturer and engineering details in the blueprint require.  And even then, in my opinion it may not be enough.  Central and South-central Texas are not immune to tornadoes and straight-line winds in excess of 100 mph.  If your builder is using this product, I can perform an inspection to determine if it has been installed correctly and make further recommendations concerning the integrity of the structure.  Call me today if you have any concerns.  The safety of you and your loved ones could be at stake.


Joe Krohn