Did an energy assessment today and captured this image of an exterior wall. I believe the wall is framed, with sheet rock and a brick facade. It is a 1929 vintage home, but I believe there have been renovations. This image is taken on the second floor and is on an exterior wall with a SW exposure. Any ideas as to this unusual pattern? I have seen a strange pattern like this before on walls that have 1970's vintage degraded foam insulation.
Shoot I have a picture of a smiley face on a wall - reason it was sprayed with something & then painted over, but it was enough to create a thermal difference that can be caught via camera only
SW exposure. What is outside? Was it sunny? Trees? Large Shrubs? I have had the shade pattern show on an interior wall.
You have a house with a Brick Facade. That means you must consider the thermal capacity of the Brick and Mortar. You also have to consider the drainage plane. On that basis I would seriously doubt any thing coming through those two components of your wall assembly. Do you have any experience with that period construction in your area or know someone who does? How did they construct the drainage plane. I've seen chicken wire or hail screen used to create the space. I've also seen multiple layers of building felt and the outer layer rots away and voila.
I would be thinking water otherwise. Break out your moisture meter. Sean's example of a smiley face is appropriate. Until you know how the wall is assembled and can account for those foibles, you have to assume the worst. Sometimes you never know. All you can do is rule bad stuff out.
I think Sean is onto the answer. The blotchyness makes me think they may have used a spray can primer like "Killz" in a can to cover water damage or mold. If they shot it on there thick enough it could create a thermal difference.
How did the surface texture of the drywall look? You mentioned it was a 1929 build...it isn't lath and plaster is it?
Is this a close up or broad view?