I'm helping a friend repair his 1910 row house... I would consider myself very handy, but I do know my limitations.... We would like to repair a 15'x15' plaster and lath ceiling. The plaster is releasing from the lath and starting to fall. We would like to attach furring strips along the ceiling and put up new sheetrock right over the furring strips. We don't want to remove the plaster and lath because this is the top floor and there is loose fill insulation above that we would have to deal with. The problem: This flat roof row house has true 4x10 lumber to support the roof, below is the 24" attic space and the ceiling below is framed with true 2x4 lumber and plaster with lath. Can we safely attach 1/2 sheetrock to the furring strips that will be over the plaster and lath and attached to the 2x4 ceiling framing? Would this be a weight issue for the 2x4 lumber?