Dave A here is some info for you this would have had me scratching my head if the owner had not been present and answered some quetions for me
These images were from the interior looking at the exterior walls A/C
operating Delta T was 14 degrees the wall studs were metal with dry wall that one could see.
Question why can you not see the wall studs with that much delta T???
BTW: this is in direct conflict with all the miss-information posted on the internet that says otherwise…
So don’t start posting all that miss-information here. Thanks.
Do the math. How many BTU’s can pass through 16ga metal 3.5" long? (actually longer if you flatten it out).
This is about “volume” of heat energy, not the “rate” of heat energy transfer.
Metal also has a lesser ability to absorb heat energy than wood.
The amount of heat that passes through a length of thin metal is also widely displaced across a wide area where it contacts the sheetrock. Harder to measure because the BTU/mass is not sufficient to increase the temp of the sheetrock.
All the math in the world woud not have helped in this situation because behind the drywall all exterior walls and the ceiling had plywood installed to the interior with drywall attached to the plywood as the owner stated one can hang pictures on the wall anywhere.
As I stated above this would have had my thinking cap on had not the owner informing me before hand. I have never had a wall covered with both drywall and plywood on the interior side
Not many homes the size of this one in OKla with 110 degree summers with some humidity that can be cooled with the size of the units that were in use
The high thermal capacity of wood studs would allow you to see them in spite of an additional layer of plywood added. You can see the studs in a wood lathed plaster wall (even through the pictures on the wall of a closet).
Btu/hr = (thermal conductivity (55k) x thickness of material (.025) x the Delta T (14F in this case)) / length (width in this case) of the stud (A metal stud is about 7" wide).
…is the reason you can’t see the studs.
Not saying the added R-Value of plywood did not increase insulation of the wall.