Its a good idea when plasterboarding ceilings to use a termal board or put insolating slabs up before the boards. This insolates the room more and increases the U factor keeping the room warming in winter and cooler in summer.
Try not to plaster just above your head, even more so when your looking up so the plaster don't get in your eyes if you drop a little.
Make sure you keep all insulation away from rressed spot lighst if yu plan to use them, also use fire hoods where nessarsy.
Plastering a Ceiling
Plastering ceiling used to be quite hard, with laying the laths then having to plaster over that with an undercoat then a finish coat.
Now days using plasterboards is a lot easier and getting the boards ready to take the finish isn't to hard, more tedious due to it being over your head.
This guide will give the basics into plasterboarding a ceiling and getting a skim coat on if needed, no techniques will be gone into depth but the same techniques as skim coating walls will be used Click here to read the skim coating guide first, and Jointing See here.
We will assume that your removing all the old laths or plasterboard first, if you not just skip to the step that's in relation to your project.
BEFORE starting make sure all electrics that have wires in the ceiling or off.
Click on some of the images to enlarge them.
Insulation
An important part of modern day construction, while your at this step it would be silly to forget about increasing your insulation.
If you have a loft above you then your more then likely to have some type of insulation already but why not add to that.
There is two options here:
- ThermaLine Plasterboards (one with insulation stuck to the back of the board)
- Kingspan or Celotex Foam Slabs
As ThermaLine Boards are just like putting up the plasterboard we will show you how to use the Foam Slabs option.
In Fig 1 you will see there is a rockwall type product between the joists, this is the insolutaion already in the loft area, if your lucky enough for this to stay there then that saves the job of laying it down after the plasterboard has gone up.
Fig 2 shows that we have used Kingspan,
What we do is working from one corner to the opposite you cut any angle or around any obstruction in the boards way and simply attach the slabs to the joist using a drywall screw, only 4 will do as we don't want to obstruct screws when the plasterboard goes over the top.
Try not to use slabs thicker then 50mm as drywall screws come no longer then 100m so after you have taken into account the thickness of the slabs then the boards thickness we still want a good fixing into the joists. Also make sure your screws for the attaching the insulation slabs are under the surface as you don't want to pierce the plasterboard.
Its a go idea to mark out where your joists are on the wall with a bit of tape or pencil mark so when you come to put up the plaster boards you know where the joists are to fix to.
Cutting the slabs is easy, just use on old or cheap hand saw and saw it just like its wood. When you come to the bits where a whole slab is to large, simply measure out and transfer the measurements onto a slab marking up in lines to follow to. It don't have to be perfect and any gap can be filled with off cuts, expanding foam or even a special foil joint tape which also creates a vapour barrier aslong as you tape all the screw holes as well. Its good practice to tape the joints between wall and slabs as shown in Fig 2.
Boarding
When using the old method of laths using extra insulation wasn't an option but plasterboarding over insulation in a solid form like foam slabs is ideal as i not only gives the room and better U factor but gives strength to the plasterboards.
The first board generally don't need cutting, normally only to avoid obstructions.
Starting at one corner to the opposite, you fix the boards to each joist through the insulation behind it.
Getting the boards to the ceiling is the hardest part, these boards are heavy, hard to manoeuvre and snap easily when suspended flat. The best way is to get a helper or use a prop or jack of some type (For info on what you can use see our Plasterboarding Tools page.)
Once you have the board in its place and supported its very important that you don't just fix to the insulation and not the joist as this will not hold. To make sure you fix correctly put a chalk line or straight edge at each end on the marks you made on the wall with tape or pencil earlier and strike the line, You put a screw every 200mm (8 inches) along every board and joist, but you don't need to measure just a guess is fine. See Fig 3.
Its also important to mark out where wires are or supports for lights etc as each board goes up, it don't matter to much if you have a loft space put if you don't finding where these wires are after the ceiling as gone up is a lot harder. To do this use a drywall saw or large drill bit to make a hole large enough for the wire to poke through, after you have finished you can make the hole to the right size once the boards are at there finishing stage
The next task is to joint the boards, for information on why we do this and the techniques involved please visit our 'Plasterboarding Walls' guide.
To summarise you tape all the joints including wall to boards (you can see this more if you enlarge Fig 3) then using joint compound you fill each and every gap joint striking it off as flat as you can. Once this is dry you can sand the compound down if not flat.
This brings your ceiling to the point where its ready for the finish, weather that's a Skim Coat then Paint or just Paint.
If your planning on having receded spot lights then you should cut the hole before Painting but after Skim Coating if your applying one.
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