Jointing drylined plasterboard ceiling

[Tony]

I just installed a new plasterboard ceiling (phew - that was a challenge!). I'm now going to do some jointing and have a few questions

for those more experienced than I....

1) I'm going to use Gyproc Joint Cement. Is this OK as a finish (i.e.

I don't need any additional finish layer on top)?

2) I recently did a little bit of patching up on a wall. At the joints I used joint tape (the paper kind). It seemed okay. A builder friend told me to use self-adhesive scrim tape on the ceiling. Which should I use - paper tape or scrim?

3) When I did the wall, I found it really difficult to get a smooth result over the joints. I sanded by hand as much as I could but the dried-on joint cement always had an edge to it which is still visible. How can I avoid this on the ceiling? Should I spread the joint cement differently? (I'm using the Gyproc guide as a basis). Should I use a power sander to get a better result? what sort of abrasive paper would be best suited??

As always any advice most welcome and appreciated.

Scott.

[Chris Bacon]

Yup.

Scrim.

Use a flat wide tool, don't overfill.

Use a wide flat hand sander. Make sure the filler is really dry.

[Ian_m]

After having just done my kitchen ceiling this weekend (+3 helpers as used

15mm soundbloc, heavy.......) my advice is, use the ready mixed Gyproc (£11 B&Q), I find it has much superior properties than mix your own, use self adhesive cloth scrim for speed, after second filling of joints (use a proper wide metal Marshaltown dry joint filler), let dry, sand vigorsously till "quite good and flat" and paint with a "mist coat" of matt emulsion (very wet mix, about 2 water: 1 paint or more).

This coat serves two purposes, enables you to see the "edges" and holes easier and stops the ready mix filler being sucked dry by the board/filler enabling you to fine fill the "edges" easily. After this sand again and mist coat any exposed filler and board. Do not use a power sander, will create undulations, I used a pole and hand sander with 80 grade paper. Keep doing this fill, sand and mist until happily flat or your arms are knackered . Then paint with lightly diluted matt (10-30% water) for first coat, as it is still lightly absorbant. Finally final matt paint, use Dulux Trade matt (yes its more expensive at £17/5l compared to £9/5l normal matt) but it is thicker so it is done it just one final coat and being thicker fills all those tiny edges, holes, scrapes and other imperfections you missed in all the a*sing around filling, sanding and misting.

Also using a bright 150W spot light at head height (or the halogen spots dangling from their wires) looking along the ceiling enables all the little imperfections to be seen. Be carefull, it reveals all !!!!, even things that won't be seen by people not having a 150W spot and head on the ceiling when in the room!!!. I once saw a decorator who had a 12V halogen spot and trasformer bolted on short length of wood doing just this to spot "imperfection".

Ceiling (all 25sq m) went up Saturday and tonight will be putting the halogen spots back in the ceiling tonight, job done.

[Ken]

The best board to use if you are not going to skim the whole ceiling is the taper edge stuff. You get a good finish with the scrim and filler. With flat edge board, you have to be really good not to show a hump at the joints.

ken

[Stuart]

I will probably have a short join where the ends of two pieces butt together .

Is it likely to be more successful if I taper the edges at that join...maybe use a small plane or somesuch ..it'll be a join of about 12-14"

Stuart

[Chris Bacon]

IMO that's the only sort to use. if you're not skimming. The "bumps" always show to some extent.

[Tony]

Thanks for all the advice. I'm going to use self-adhesive scrim tape and gyproc joint cement applied with a 6" metal jointing knife. I also got a pole sander and some 80 grit paper.

I used tapered edge boards, but will have problems where the boards meet on the untapered edges (the short edges top and bottom). I'm just going to do my best there.

[Tony]

I did the job a week ago as described above and have since sanded, primed, painted and cutout spotlights. I have to say it looks bloody brilliant. It's the smoothest ceiling in the house, and repeated filling, sanding, sanding again and more sanding really makes all the difference.

In the end I used three (or maybe even four) coats of primer (because I had some much and didn't want to waste it) and I think this had something to do with the final result. I also applied about three coats of white paint which again covers any fine imperfections.

With spotlights in place pointing downwards, the focus and attention is drawn away from the ceiling anyway and any remaining imperfections are not at all noticeable.

I did need to fit coving to cover up the gaps around the edges of the ceiling, but otherwise job done.

Thanks for all your help.