cracks in ceiling

[MM]

That was kind of my first reaction when I read this. After all, the house is not going to fall down because of a few hairline cracks in the ceilings.

MM

[MM]

Worked for me, though. On ceilings and walls. As someone else said, carefully applied it needs no sanding. I smoothe over and feather the edge with a moist sponge. Couple of coats of emulsion and they're gone!

MM

[Dave Plowman (News)]

No it's not - provided you take the time to do it several times. And since it dries so much more quickly than hard fillers, not so much of a problem as it sounds.

I repeat. Several of my ceilings are done in this way and cracks have appeared between boards. A modern plaster skim can't cope with near any movement - and wood joists have a habit of moving.

[The Natural Philosopher]

IF you rake the joints out to a decent width, it will work, as there is some length to flex over.

But that's not a simple butt joint then, is it?

[The Natural Philosopher]

which is why the tape is used. To reduce the movement to zero.

What happens is that you construct a stressed skin shell of plasterboard: the actual woodwork moves independently of it, as the holes the mails or screws use open up slightly.

[Dave Plowman (News)]

It would need to be made of something stronger than the usual hessian, then. Or even the modern plastic stuff.

The theory may be fine. The practice isn't. It is of course better than no scrim at all - but not perfect.

And if it does crack fill with decorator's caulk. That works. ;-)

[MM]

I didn't rake anything out. But I DID use extreme pressure to force the gunge as deeply as possible into the crack. These, however, weren't hairline cracks, but about ¼mm wide.

MM

[MM]

What if one accessed the other side of the plasterboard from the loft (in the case of upper floor) and worked on the crack from both sides?

MM

[MM]

What I've used before is white correction tape from Staples. Smoothed down it becomes invisible anyway, and you can apply several layers.

Another idea, which I HAVEN'T tried yet, is that incredibly thin but tough tape that one wraps around a plumbing joint.

MM

[PeterC]

And then try to get something to stick to it!

[Dave Plowman (News)]

No point in giving yourself more work. Just rake out the crack and fill as I said. I've done lots like this with success. But you do need to persevere since it shrinks.

Err, that's PTFE. Similar to a non stick coating. ;-)

[The Natural Philosopher]

well mine appeared to be glass.

Only if the crack is wide enough.

[Dave Plowman (News)]

So an even bigger crack with flexing? ;-)

You rake it out a bit. Same as any crack.

[MM]

Paint?

MM

[PeterC]

Teflon?

[Mike P the 1st]

On Thu, 01 Apr 2010 20:20:36 +0100, MM gently dipped his quill in the best Quink that money could buy:

What a good way to spend the Easter break ... ripping up all the floorboards or just disturbing all that itchy insulation to search for the crack, then discovering that it is obviously not cracked right through the board on the top side so you cannot find it.. Fixing floor back and managing to put the wrong longer screw/nail into a water pipe and flooding the void until it hits an electric junction box and plunges the house into non electric mode just when the wife has left you three loads of washing to get done by the time she comes back from seeing her Mother who thinks you are a complete numpty anyway. Happy Easter :-)

Mike P the 1st

[Merryterry]

I agree with this posting but will put it into other words. The filler musty only be in contact with either side of the joint. You must somehow put a 'bond break' into the joint to stop it bonding on three sides. Imagine a section through a rubber band. Fix it to a surface by three of its four faces and it wont expand. The depth of a filled crack must never exceed twice the width.

[MM]

Well, if the crack doesn't go right through, the board can't be flexing all that much so a surface treatment with something like Polycell Hairline Crack Polyfilla should keep the crack hidden for several years. On the website: "Permanently fills hairline cracks without having to scrape them out."

MM

[Mike P the 1st]

On Fri, 2 Apr 2010 07:41:59 -0700 (PDT), Merryterry gently dipped his quill in the best Quink that money could buy:

Do you mean that you should NOT pack the crack full. but leave a gap on the crack's upper/top side with caulk or whatever, thus making a bridge and not filling the crack completely to the top ..... if you see what I mean.

Bye George .. I think I've got it !

Mike P the 1st

[Dave]

You have hit a nail on the head with that answer.

Why do wives assume that all jobs are simple and can be done by a simpleton?

Having worked in the development field, almost all my working life, I look at a job and the first thing runs through my mind is..

WTF can go wrong and how can I prevent it?

I have been known to put of what looks like a minor job for weeks while I think it out. Much to the annoyance of my wife.

Dave