Originally Posted by
SAL IACONO
It may be a combination of both as I found some outsulation at the roof top (3/4" foam with nylon weave holding about 1/8 to 1/4"" coating).
"Outsulation" is the brand name DryVit uses for their EIFS system.
That nylon weave is applied all around the edges to protect the edges and allow for the edges to allow for the EIFS finish coat to be applied to, and adhere to, the EIFS foam. That mesh tape is applied to the front, then wrapped over the edge, then up the back side.
I was really under the impression that all of these systems should have some way for the moisture to escape. Apparently not!
You are correct by stating "should have" in that all those systems *SHOULD have* a means by which to allow moisture vapor to flow through the wall. However, putting up vinyl wallpaper is akin to putting plastic sheeting on the wall and taping and sealing it up - *NO* moisture vapor will go through a wall with that covering it, either from outside to inside, or from inside to outside.
Regarding pressure differences on your other post, the only way to equalize the pressure is to leave all of the doors open all of the time. Opening a door will temporarily equalize the pressure if open long enough, but when the restaurant is in operation, their exhaust fans will also be in operation, and as soon as the door closes ... the exhaust fans will create more negative pressure.
If I recall correctly, and maybe Scott can correct this if this is not right, the pressure of a structure should be no more than 0.5 to 1.0 pascals negative (maximum negative pressure) to a positive pressure.
Too much positive pressure is also not good, it simply drives all the conditioned air out, which means that air must be replaced with air from someplace, and that new air must then be conditioned. A big waste of energy.
I believe the recommended state for a structure is either neutral pressure or slightly positive, many 1 to 2 pascals positive pressure.
Scott explained a giveaway sign very well: the doors should open outward, thus, it should be easy to open the door and you will feel a slight breeze if the structure has a positive pressure, however, the doors will be difficult to open under negative pressure as the negative pressure is literally sucking the door closed, and, when you do open the door, you will fell the door being sucked back in - that's not good and it indicates a negative pressure is inside.
If you are not sure, tape a sheet of plastic over the exterior side of one door, then, from inside, slightly open the door. A positive pressure will blow the plastic away from you, a negative pressure will suck the plastic in toward you.