In older houses, the ceilings were usually made of lathe and plaster. This comprised wooden lathes nailed to the underside of the ceiling joists which were then coated with plaster. The lathes acted as a 'foundation' for the plaster to stick to. When the plaster was applied it would have been troweled on so that it squeezed between the lathes and formed nibs on the other side to hold the whole lot in place.
Over time these ceilings can become damaged due to a number of factors - leaking plumbing, vibration from work in the room above, as well as from inadvertant footfall in the attic. Small areas of damage can be carried out by following the guide to Lathe and plaster - minor repairs
If the ceiling is extensively damaged or loose, the best answer is to take it down and replace with plasterboard. Removing the old lathes and plaster is an incredibly messy and dusty job so plenty of forethought and preparation are required.
Safety equipment is essential. You will need protective goggles, gloves, face mask and hard hat.
Prepare the room
Prepare the room by removing all furniture and carpets including the underlay. Dust and debris will damage this if left in place. Remove shelving, wall lights and other fittings which may be damaged by the dirt. If you have a ceiling light, this should be removed. Switch off the lighting supply and remove fittings. Protect and isolate the conductors by securely fixing in a terminal block or junction box. Leave all the mains power off while you are working to prevent possible accidents.
Removing the rubbish
You will probably need a skip for all the rubbish so get in touch with your local skip company beforehand so that the skip is on site when you start. Either use a wheelbarrow to transport the rubbish to the skip if it's on the ground floor or, a good supply of strong rubble sacks.
Walls can be protected by covering with polythene sheeting fixed at the top. This will minimise the collection of dust on them. Protect the floor with heavy duty sheets. This makes it easier to do the final clear out as, once the main rubbish has been cleared from the room, they can be lifted and emptied into the skip. This avoids the need for too much sweeping of the room creating dust. Seal doors to other rooms / hall / landing with tape and open the windows to allow plenty of ventilation.
Set up a scaffold platform to work from so that it's just the right height. If you don't have access to a platform, you can make one with stepladders and scaffold boards. Make sure that they are strong enough and stable before starting work.
Removing the lathe and plaster
Use a cold chisel and hammer to break away the first section of plaster. Do this at a point where you are certain there are no cables or other services above. With the first section of plaster out of the way, you should be able to use a wrecking bar to gradually prise the lathes away from the joists and remove a section of ceiling at a time. Take great care as there may be cables above as well as other services. It's actually a lot easier if you work your way accross the room methodically rather than using a haphazard approach. Once the bulk is down, work your way back accross the whole ceiling removing any remaining lathes and nails in the joists.
Finally brush down the joists to remove dust and the ceiling will be ready for plasterboarding