install suspended ceiling between old beams

am about to tackle a project that i probably should not.
volunteering for a nonprofit that owns an old 2-story house.

first floor has old (150 years) beams (5"x 8") that are exposed.
some are hand hewn, others appear to have been produced by a saw mill.
we would like to leave at least the lower half of the beams exposed.
but the underside of the floor above needs to be covered up. (nails protruding, holes, gaps, etc.)
we would like to install suspended ceiling between the beams, without making contact with the floor above.

however, the beams are not evenly spaced and some are bowed.
some beams are 28"- 30" apart.
(one beam is so bowed that the space between it and the next beam varies from 30" at the ends to about 35" in the center).

any ideas or suggestions most welcome.
we're thinking improvising luan panels, as commercial panels probably won't be wide enough. also, expense of supporting channels might be an issue. (no, we're not getting paid)
how to scribe the panels to be flush with the beams?

much appreciate your thoughts.

 

The title of your post said suspended ceiling & your last question is how to scribe the panels flush with the beams. If they are flush, the ceiling isn't suspended. Can you post some pics?

 

Can you screw light gauge steel track to the sides of the beams and put steel studs between the track to accommodate a new drywall ceiling between the beams?

That would facilitate installing the drywall and even if you don't get a close fit you can mud in the gaps to the beams with a hard setting joint compound.

 

Thank you both for your replies.
I thinkwe've resolved the issues with a bit of professional input and have decided how to proceed.

With regard to your note (If the ceiling is flush with the beams, it isn;t suspended), I probably should have been a bit more clear. We asked how to make the ceiling panels flush with the sides of the bowed beams. The ceiling will most definitely be suspended from the floor above, not flush with the bottoms of the exposed beams. We will be constructing a grid with 1"x"3" furring strips between the beams and stapling the panels to the furring. That will leave the lower 3"+/- of the beams exposed, and allow us about 3 1/2"+/- above the grid for insulation.

With regard to the need to scribe the panels, we're told that is the best/easiest thing to do....even though it will be a scary task. Using light weight metal strips is just not in our budget (therefore, the decision to go with furring strips).

We'll be tacking the furring strips to the sides of the beams (that is, running parallel with the beams). Then, we'll be screwing other furring strips perpendicular to the runners (that is, across the spaces between the beams). The perpendicular strips will be 12" apart from one another. That sure sounds like a lot of weight hanging from the runners, doesn't it? But, the pro we've talked to indicates that the weight will be evenly apread out and secure. (So, for example, if the space between two beams is 39" we'd have the weight of three 12" square panels stapled between two perpendicular furring stips. Hopefully, that should not result in any sag).

Thanks, again, for your input. This is a learning process and the only way to learn it is to do it, I guess.