Hairline Cracks

Discussion in 'Car and Van Talk' started by Raul B, May 2, 2016.

  1. Raul B

    Raul B Member


    What's the best material to use on hairline cracks without causing too much trouble on a levelled plaster surface?

    I've found it extremely difficult sanding down filler and then painting for a perfect finish regardless of whether I use filler or caulk etc?

    P.S. I've got a hairline crack on 1 ceiling (might be wider than a hairline crack in fact) which keeps and reappearing even after applying filler/caulk several times - arghhhh! Any suggestions please????

    Thanks in advance.
  2. KIAB

    KIAB Super Member

    This is my favourite filler, lovely filler to work with, easy to applie with little sanding.

    You don't say how long crack is, so we have to guess,usually the cracks are were the plasterboard sheet butts up to the next one, & joint hasn't been taped.

    I would use some plasterboard screws to pull ceiling up tight to the joists,so no movement, then open the crack up slightly & refill with filler.
  3. If you decide to open up the crack first, brush it free from dust (vacuum) and liberally brush in a slightly diluted (20%?) coat of PVA - repeatedly until it absorbs no more.

    Use a damp cloth to clear away any from the surrounding ceiling surface before it dries.

    If you don't widen the cracks, then try a ditto with a more diluted (30+%?) PVA - brush it back and forth over the crack and watch to see if it gets drawn in. Sometimes you can brush it on to the crack so's there's a nice ripple of PVA over it, and it'll get drawn in by capillary action. Keep it wetted when it does this - you want as much sicked in as poss.

    With a bit of luck this will bond the crack and help prevent it from moving again.

    Ditto with wiping away excess from the ceiling surface - you don't want dried PVA on there.

    Then fill...
    tore81 likes this.
  4. KIAB

    KIAB Super Member


    Makes the ceiling, difficult to paint.

  6. KIAB

    KIAB Super Member

  7. Raul B

    Raul B Member

    The ceiling crack is from 1 end to the other. It's been newly skimmed recently (several months now) and scrim tape was definitely used...

    Attached Files:

  8. Jitender

    Jitender Screwfix Select

    Does look where the plasterboard has been joined.

    Is the ceiling in the first floor, and can access to the loft possible, maybe missing a batten on the joint?
  9. Yeah, but you chust try living without it. :p
  10. KIAB

    KIAB Super Member

    I do.

    406 or SBR;)
  11. Oooooh - I'm gonna need a bigger font... :rolleyes:
  12. tore81

    tore81 Screwfix Select

    I always open up the cracks in plaster which I was dubious about at first.

    In my experience you can't hide it with out opening up, filling.

    Then another coat feathering out.

    If you just fill over you are creating a bump which will show up. i would use dry wall mixing compound. But I'm sure there is other stuff out there. But that is the only filler known to me that works a treat.

    DA stuff is probably worth a go as Dry wall is ready mixed but only in big tubs.
    KIAB likes this.
  13. KIAB

    KIAB Super Member

    Agree, I also prefer dry wall filler like Gyproc Easi fill, but it's only available in 5kg bags or larger, which is why I suggested Toupret instead.

  14. Glue yer crack shut first, man - I'm tellin' ya...
  15. Raul B

    Raul B Member

    It is where they've been joined. Ceilings on ground
    What's the best way to open up the cracks?
    So you wouldn't recommend caulk or this product -
  16. KIAB

    KIAB Super Member

    I just use the edge of my filler knife,could use a utility knife & draw along crack.
    tore81 likes this.
  17. Raul B

    Raul B Member

    I'm assuming you scrape over the crack? How wide should I make it?
    Does this apply to hairline wall cracks too?
  18. tore81

    tore81 Screwfix Select

    I tend do make a v line grove with my Stanley or filling knife.

    It basically needs something to grip to.

    1st coat keep flush

    2nd coat feather out.

    On board cracks I have used tape after the 1st coat then probably do two more, but if you are sure it's there I would just fill.
  19. DIYDave.

    DIYDave. Screwfix Select

    Long ceiling crack - main thing is to eliminate any movement otherwise, whatever method and filler you use, will crack again in no time at all

    Push the ceiling boards either side of crack ......any movement ?
    If yes, as Kiab says, extra screws, PB screws if possible. They will self countersink a couple mm below plaster surface to allow a wipe of filler to be applied over screw heads

    Hopefully, the PB joins meet on a joist, allowing screws to be driven in

    If the floor above and / or jousts have movement or bounce in them, this could be causing the crack and unfortunately is harder to rectify
    tore81 likes this.

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