Can vapor drive be responsible for blistering exterior paint? Is this to be expected? Solutions?
1941 house in Portland, Oregon (climate zone 4C).
Original uninsulated walls, cedar siding and lead paint.
I had the house painted 2 years ago and have had blisters ever since (see photo) primarily on the walls with direct sun exposure. Painter has returned twice and sanded/repainted the blistered areas. He stated that this is normal for this type of house and is caused by vapor drive. He stated that the blistering will continue.
Some blisters contain liquid water.
Internal RH typically ~50%.
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