fixing plasterboard straight to concrete ceiling

[jordy_boy]

Hi everyone wondering if you could help please

I've just had a porch fitted with a pitched roof put over the top of an old existing concrete flat roof. this now means that I want to fit plasterboard directly to this old concrete ceiling. The problem is I can't afford to lower the ceiling enough to even put batons to fix the board to so I am wanting to fix it directly to the ceiling. What is the best way to do this? Can I use some of those masonry screws to fix the boards? Tapcons or walldogs? I think is the names

Many thanks

 

[cherryred]

How about plasterboard adhesive.....dot dab. Might do the trick

 

[dougalhouse]

How about painting with blue grit leave overnight or longer until it dries then bonding coat then skim over or as cherryred said; dot and dab.

 

[jabuzzard]

Something like Screwfix 12531 with a 4mm masonry bit say 81471. Might be worth considering 9.5mm plasterboard as well if high is an issue. A bit expensive but it will do the job.

Alternatively you could try plasterboard adhesive spread with a floor tile adhesive spreader, and stick it straight on assuming the concrete ceiling is level.

However I would have thought your best bet if height really is an issue is to get it plastered directly on the concrete.

 

[jordy_boy]

Thanks for the replies everyone. I forgot to mention the new roof extends further than the old one so there is part concrete ceiling then a void with beams to fix to so that's why I didn't plaster straight onto the ceiling.
the ceiling is pretty good for level so I might just go for the adhesive option then as I will have the beams to fix part of it to which will help hold it.

Also I can board it with one sheet but it will be very awkward getting it in the porch so I was thinking splitting it in 2. Will that be ok or do you think I might get a crack on the join because of the different backgrounds.

Thanks again for your help

 

[jabuzzard]

If you possibly can use one sheet of plasterboard. If you can't make sure the join is not at the boundary of the concrete and beams or you will almost certainly get a crack.

 

[jordy_boy]

ok thanks I will try for one. But if I do need to split it the join will go at right angles to that anyway.

 

[NickB_99]

I forgot to mention the new roof extends further than the old one so there is part concrete ceiling then a void with beams to fix to so that's why I didn't plaster straight onto the ceiling.
the ceiling is pretty good for level so I might just go for the adhesive option then as I will have the beams to fix part of it to which will help hold it.

Also I can board it with one sheet but it will be very awkward getting it in the porch so I was thinking splitting it in 2. Will that be ok or do you think I might get a crack on the join because of the different backgrounds.

With a void you could still go for the full plaster if there was a possibility of getting a full strip of plasterboard in the recess that would make it flush with the surrounding concrete. I agree that in this case, covering the full area with p/board is probably your easiest option.

I've never used drywall adhesive on a ceiling, but have used it on walls and the stuff is quite 'slippy'. In that you need additional p/board spacers at the bottom to prevent the boards sliding down the wall to the floor. This would be my only concern with using on a ceiling. Boards are not light and you're relying on wet adhesive initially to hold and keep level.
I would suggest if you do use the adhesive, maybe consider some small-ish screw-in frame fixings e.g. screwfix 33429. Then would be kind of belt & braces to make sure your boards well stuck and level.
Where you screw into the joists with drywall screws I'm sure you'll be secure in that area.

Agree with the jabuzzard a join will be fine if you need to, and as discussed at right angles is best. Just need to ensure scrim tape is used on the join prior to skimming.