I have been redoing certain rooms with drooping/broken plaster over the past few years. I am doing my first ceiling and after removing the plaster and lathe there are 1"x3"x4' pieces of wood going perpendicular to the joists(this allowed the lathe to be put in parallel to the joists) that are spaced about 8" apart. I dont know if they are for support or what as I have not seen this in any videos on the internet (there are not many that I can find on plaster ceiling removal) with this type of bare ceiling. Are these safe to remove? I would like to take them down to install insulation boards before putting up drywall. Thanks all.