I see this very seldom - stopping air flow with spray foam - a best practice!
Slowly builders are coming around to the idea that spray foam over the rim joist helps a whole lot toward controlling temperatures between floors. After all, the area between the floor and ceiling is a space that is typically not insulated. Rim joists are insulated, but, in my opinion, badly, with a small piece of fiberglass poorly fitted into the space. Air infiltration is common and poorly managed.
Since that area is so large, not controlling the temperatures in there will do a lot to affect the environment indoors, and the efficiency of any HVAC system.
Controlling air flow before it can get into the space is a huge contribution toward HVAC efficiency.
Spraying the rim joist in this way is, in my opinion, a Best Practice. I have posted on this before.
Covering it with insulation afterward provides a great R-value in addition.
In a recent new construction inspection I saw something I have not seen before!
This is certainly a
I would love to see this catch on!
You are looking at part of the ceiling of a three-car garage.
What is the most frequent complaint in rooms over garages?
THEY ARE VERY COLD! IT IS HARD TO HEAT THEM!
Over this garage is the master bedroom, master bathroom and a bonus room, separate with its own staircase.
The entirety of the underside of the sub flooring, and the rim joists, have been sprayed with icynene foam.
BUT THIS IS A VERY THIN COAT. IT LOOKS TO BE ONLY ABOUT 1/2".
Icynene foam has an R-value of about 2.5 per inch.
So, obviously, this coating is not to lend much to the R-value under those rooms.
THIS THIN COAT IS INTENDED ENTIRELY TO CONTROL AIR FLOW. OVER THIS WILL BE THICK, BATT FIBERGLASS, WHICH WILL CONTRIBUTE AN R-VALUE OF 30 TO THE SPACE.
This is a builder/architect/designer thinking ahead!
Icynene foam is very expensive if sprayed to a depth intended to provide sufficient R-value.
But as a thin coat, combined with fiberglass, an EXCELLENT thermal barrier is provided and much more cheaply!
This was impressive to see and explain to my clients. I even complimented the supervisor when he stopped by on this fabulous
Again, I hope this is a Best Practice that catches on!
My recommendation: when you are buying what will be called an "Energy Saver" home, find out what criteria will be followed. This home is constructed to meet RESNET standards. In addition to that, find out pre-construction what things will be done to the home to help with compliance. This kind of spray foaming would be an excellent thing to see before you buy the house!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560