A reader wrote in to Holmes Magazine and asked: I’ve heard that oil paint can also act as a vapour barrier and on the wrong wall assembly it could be a disastrous choice? We just moved into a new home and all the walls are pointed with oil, what wall assemblies are dangerous? What should we do?
The magazine published Ken's response:
Thanks for the question. This is really more of a building envelope question than a painting question.
It is true that the oil-based (alkyd resin) paints are less permeable than conventional latex paints. Up until the 1970s, most homes had alkyd paints on the walls.
This shouldn't be a problem. There will be many other through-wall areas for moisture and air to migrate particularly in homes of this age. If your home is newer, I still doubt it is a hazard. Typical construction has a poly vapour barrier below the gyproc (drywall) and so making the drywall layer less impervious to air and moisture migration shouldn't cause additional problems.
Remdal Painting & Restoration Inc