Hey there all - we are working on a flip where we got into a 2-story townhouse with units on either side, and we have realized we have a chain smoker in each of the adjacent units. The unit has popcorn ceilings, and we plan to remove them and then use the Zinsser BIN Shellac primer on walls and ceilings in every room. We are currently spackling and filling holes in the walls, and will also rip off the baseboards and use spray to seal smoke from coming in under the drywall.

Our popcorn ceiling contractor can start work in July, and my question is about timing.

My wife, son and I could go in and wash all walls and do the Shellac BIN primer over the next few weeks, but it would then be sitting there without the ceilings done for 1-2 more weeks. If we do the walls and ceilings a few weeks apart, is there any disadvantage to that? I'm wondering if by having the walls done but the ceilings still leaking some smoke in, we might get some of those smoke molecules trapped in our unit. Or will our AC running clean those out? 

Or is getting shellac on any wall at any time helping improve air quality in our unit, and if some smoke gets in while we wait to finish the ceilings, we can just run an air purifier or ozone machine to remove those odors from the unit after we finish the ceilings a few weeks later.

I welcome all advice on whether we should wait and try to do the shellac all at once, or move as fast as possible to start sealing indvidual walls ASAP.

Thanks!