Every other vinyl siding panel on the market would have the same airflow behind it... they just wouldn't absorb it's moisture and lose R-value in the process. Airflow is NOT the solution to moisture... as a matter of fact, it's the primary carrier. If you are referring to infiltrating or exfiltrating moisture in the form of water vapor that affects a wall cavity or a structure, that needs to be addressed on the immediate inside and outside of that cavity.
You are missing my point. I am not speaking of air flow carrying water vapor behind these type products, because there is no air flow. They are up tight to the vapor barrier just like a piece of glass on a coffee table. Water is the issue I am trying to address in my concerns.
Let me go back for just a moment to my work in Alaska working for NPRHA through HUD to explain what I have seen to make me have concerns.
The first year I went to a village, siding had already been done the previous two years with "modern" building methods. What we found upon arriving was beyond belief. Siding that had been done 6 months before was laying in piles on the ground from the galvanized nails rusting off. On slightly older year and a half old jobs, T-111 siding behind sheathing-taped Tyvek had completely rotted away in places and much of the "protected" T-111 siding was nearly at maximum readings for moisture content when checked with a Protimeter. Even every staple that originally held on the Tyvek was gone. We were working very closely with NPRHA and HUD after these failures to come up with new procedures to waterproof, flash, and hang these products successfully in wet extreme environments. This particular village I worked in receives about 200 inches of annual rainfall. Just one 4-unit building sustained $250,000 in damage, so there was no messing around with the procedures we were told to use. These procedures the engineers came up with I still largely use today. I even believe engineers at NPRHA were the original people who came up with the idea to use bituthane strips to flash window nailing fins. We used it much more than just around the windows on these buildings. It was several years later that I saw the first use of this type of window wrap being used on new construction in the lower 48.
One instance that changed my view of vinyl siding forever was a rainy day my first year there. 50+ mph winds had driven the rain through the vinyl siding, up the wall, past the soffit channel, and into the attic where it ruined the ceilings below. After ruling out a roof leak, we took the siding off to investigate what the cause might have been. I was shocked to see just how wet walls can get behind vinyl siding even out in the middle of a wall.
Even in more moderate climates, the vinyl J-channel around windows and doors funnels the water straight down the sides where it then ends up behind the siding. If anyone thinks all the wall area behind vinyl siding stays dry, they are mistaken.
OK, back to my expanation of my concerns about the dow foam.
The blue foam is overlapped in a ship-lap fashion when installed, leaving virtually no way for drainage I can see, except straight down and out the bottom. With two slick surfaces tightly together (the vapor barrier and the blue foam), water tension will surely hold the rainwater from quickly draining. I would suspect that water could stay trapped for days if not weeks.
When homes are wrapped in a home wrap, there are many weak spots in most installations, such as around windows, doors, electrical outlets, dryer vents, as well as the thousands and thousands of nail holes created by the installation of the product. Traditional vinyl siding has been designed to get this water away from the home wrap and through drain holes as fast as possible to minimize the chance of water breaching this barrier.
This is my only
concern with this blue foam backed siding. It's inablilty to get water out from behind the siding as soon as possible before it starts to cause water infiltration problems around nails, staples, and areas with improperly installed wrap and flashing.
This is my opinion that I am entitled to the same as if someone won't use a certain window for a particular reason.
Everyone else..... feel free to use and sell it all you want.
That's all I have to say on siding. Now... back to talking about windows.