Hair line cracks on ceiling

[asalcedo]

What is the best way to repair hair line cracks on a lath and plate

ceiling?

The standard way, and what my decorator is doing at the moment, i raking out, filling in and sanding down.

The problem is that after this is done the appearance is not very goo a couple of cracks have already been done at home. One can still se the uneven celing and the protruding filler along the crack.

Also, I wonder if the cracks will reappear in a short time.

A different decorator mentioned that they would treat those cracks wit a thin painter's tape covering the crack and fine sanding the edges o the tape.

When I suggested that to my present decorator, who seems to be ver experienced, he thought it was a bad idea, and mentioned that the tap is mainly used in plasterboard.

Another question, is there a filler that is more appropriate so tha the cracks do not reappear?

Thanks,

Antoni

-- asalcedo

[Rob Morley]

If the plaster is uneven across the crack then the more plaster you cut back, the less apparent the unevenness will be (but the more work you have to do). If you apply the filler carefully it shouldn't need sanding - build it up then scrape over with a straight edge (steel rule, plastering trowel ...) so it doesn't stand proud. When it's dried off a bit, skim with a thin coat just to fill any imperfections without building it up any further. The original cause of cracking won't go away unless you replace the ceiling, so it will progress. If the movement is seasonal you may find that cutting back a minimal amount and using a flexible filler will prevent the reappearance of cracks, but it will still look uneven.

[Uno Hoo!]

An alternative - if the cracks are fine, is to use flexible ceiling paint as opposed to standard emulsion. I have used this paint on my (extended) kitchen ceiling and it worked a treat. The paint actually does 'stretch' without splitting and is excellent for hiding and covering fine cracks.

Kev

[Chris Bacon]

Don't. Just *don't*. Do this, instead. Get a squeezy bottle, and C. 2" of foam pipe lagging. Clean the bottle. Tie lagging around the neck (remove the nozzle first). Make sure the seal is good. Get some 2" re-inforced waterproof tape, and wind it around the lagging (to keep the split together). Cut off the lagging/tape to make a flat surface at the top. Get some 5:1 water:PVA and fill the bottle. Push the flat surface of the cut off lagging up against the crack, so that the lagging makes a seal, and the hole in the middle straddles the crack. Squeeze, and some PVA will go into the crack. You can sort of rythmically squeeze the bottle, so that the PVA mix is forced in with a sort of "donk.. donk.." sound. When the PVA is dry, it will a) glue the edges together, and b) (important!) stop the edges moving together, and allowing sand to drop through, which knackers lining paper, forces filler back out, etc. Any sandy stuff in the crack (ooh-er!) is a positive advantage, as it will help fill the join. N.B. PVA mix is likely to drip, so wear a hat, and wipe any drips off after applying the PVA, or it'll show when you decorate. N.B. if you rake out the joint, the PVA mix will piss out all over the place, and not go into the crack properly. This will stick the whole flippin' sealing back together. Mark out cracks with pencil before applying PVA. If necessary, let it dry for 24 hrs. before putting more in. I've used this method quite a lot, and it really works (also on plasterboard joins, reasonably). For cracks wider than hairline, use thicker PVA:water.

[asalcedo]

Hi Chris,

That sounds like a cracking way to treat cracks.

I have a pointing gun that can be used with softer materials, lik grouting for tiles, will this work as well?

The system with the squeeze bottle and pipe lagging you describe is no that clear to figure out.

So, if I get it correctly, the idea is to get PVA glue inside th crack. Right?

Will this not stain or leave a mark along the crack?

Thanks,

Antoni

-- asalcedo

[Chris Bacon]

It glues the whole lot back together, and stops the edges of the plaster gently rubbing together and dropping sand/lime down the crack, where it collects and bulges out your paint/paper or displaces your carefully applied filler.

Don't think so - the idea of the lagging is to seal against either side of the crack so that PVA mix is forced up. You squirt some in, move along the crack, squirt more in, move... (repeat).

See attempted pic. below.

Yup - it works well as the PVA:water mix is very runny, goes right into the crack, and gums it up good'n'proper, if there's dust or sand in there it sticks that too and makes an even better repair.

You should wipe a sponge along to collect drips before they set to form hard lumps of PVA, then you can wipe some filler on if needed, with a filling knife. It doesn't stain.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /

[asalcedo]

Great, I think I understand well now.

Will the Climaflex pipe lagging do?

have some of that.

I am very keen to tell my decorator to try it out. If he does not do, will try myself over the holidays.

Thanks,

Antoni

-- asalcedo

[asalcedo]

One more detail, is this PVA ok:

Antoni

-- asalcedo

[Chris Bacon]

That's just the ticket.

It seals much better if you don't rake out the cracks, I had to cut the face of the lagging that I pressed up against the ceiling into a contour for a couple of cracks that I *did* rake out: ^ _,--'^'--, _- ^ -_ _.' ^ '._