So I just removed staple on ceiling tiles from my curling to find they were done on top of plaster, my questions are:
1) is there any fear in any case of the drywall adding to much weight to the ceiling? This house was built in 1908.
2) when installing the drywall do I attach along the furs or along the studs or where the fur overlaps the studs? The old tile where 12x12 so the furs are 1 ft spread if that makes any difference.
Hanging drywall over old plaster is very common. If the existing strapping is securely fastened to the ceiling, you should be able to hang sheetrock. I use 3/8" rock all the time over plaster walls and ceilings. The weight is not an issue. You may want to check, using a stud finder to assure yourself that the strapping is attached to the underlying floor or ceiling joists. It certainly would not do any harm to find the joists and add a screw into the strapping to be sure it is secure. The only time you might have a problem is when the strapping is only connected to lathes, and if the weight of the rock held only by lathes may sag if the lathe nails are not secure into the joists. Good luck, go for it!
Leave your firring strips in place, but make sure they are fastened tightly to the joists at the intersecting points. Plaster as a rule is 3/4" thick including the lath, although it can vary, especially in turn of the century homes. The firring should be 3/4" thick too. You will want a minimum of 1" penetration into the framing to secure the firring to the joists, so 2 1/2" to 3" screws should be ideal. You will not want to go over kill on the length for you may hit something in the ceiling you may not want to. As I mentioned before 1" into the framing will hold anything in the way of sheetrock you install. Pilot the screws through the firring only will help.
After that you can install the sheetrock any way you choose. I have run it with the framing, I have run it across the framing. Either way will hold fine, though some people may beg to differ. But hanging drywall is not rocket science. Set your screws the proper depth, which is critical. There are special drive tips that govern the depth for you.
As note, now is a good time to update the wiring in the ceiling PROPERLY, but you may need to open walls to do so.
If the ceiling height is tight, but I think you may have high ceilings anyway, you can remove the firing strips, which will let a lot of plaster fall, (not good) and screw the drywall straight to the ceiling. You will need to find the joists to some degree, although the lath is capable of supporting SOME of the weight, I would not rely on it solely. This would take approx. 2" screws to hold this up. If the plaster is for the most part intact, except for a number of small holes from the nails, you can use 1/4" drywall to overlay the plaster.
For my opinion, I would stick with going directly over the re-secured firring strips with 1/2" sheetrock.
If you decide to drywall over the ceiling, I would suggest to use one the new lightweight drywall panels. Maybe more to save your back, then the ceiling. I have some limited personal experience with homes built in the early 20th century, and have some things to take into consideration:
The joists and ceiling framing in houses built in the early 20th century are undersized by today's standards. This is with my experience with Philadelphia row homes at least. You want to evaluate this possibility along with other sources of load placed on the joists since the home's construction, such as drywall added to plaster walls on the second floor, and multiple layers of flooring. I don't think that you would have catastrophic failure, but if the joists are undersized, and they sag, you may want to consider taking the plaster down and sistering the joists. This will allow you to fix any wiring and add nice things like recessed lighting. In my case, someone had already drywalled over the plaster, so I decided to take up the floorboards on the second floor. If you do have sagging, and you do not sister the joists from below, you will have to do it from the top to fix any problems (bounciness, sagging). The floor will likely not support the additional weight from self leveling underlayment, and you will not be able to take out any bounciness without sistering the joists.
