"Out-There, Left-Field" repair idea for Ceiling cracks (opinions please...)

Hello Again Chaps,

In a recent separate thread, I related how my Ceiling had cracks along several of it's "Recessed" joints, due to the lack of any "Backblocking" behind these joints. I've been able to scrape out the existing Tape and Compound back down to the Plasterboard itself along the joints, but I was wanting to do something a little stronger than just Paper Tape and Compound again, so that the problem didn't recur.

An ingenious suggestion was made by forumite Rod'49 to screw in a certain kind of fastener along the centreline of the joints in question, and I tried a couple of these today, and indeed they do the job - although more than one per batten-gap looks like being required to stop differential movement between the sheets.

Anyhow, yesterday afternoon while I was fossicking around in the garage, I found a thin piece of galvanised perforated metal, and the crazy idea came into my mind of using strips of this stuff along the joints instead of normal Paper Tape. With this in mind, I tried two tests:

1) I plastered a small piece of the metal to the edge of a scrap piece of Plasterboard with Cornice Cement, in order to test the "pry-off" resistance of the stuff...
Well, this morning, I was able to lift the edge of the Plasterboard scrap (which measures about 1.2m x 1.2m x 10mm thick) up, from the outside edge of the metal strip. You can see the strip in the photo below. It's contact patch with the Plasterboard was only about 100mm long x 25mm wide, and I was doing the lifting from another 40mm out at the metal strip's other edge. It was the Plasterboard's own paper coating that eventually gave way...
My own personal conclusion is that the grip between sheets along the joints that this stuff would generate would be adequate for the job in question...

2) I then cut up another piece of the metal to a width of 65mm, to see whether it would be thin enough to be plastered over (it's about 0.6mm thick) within the 70mm-wide groove that I had scraped out of the Ceiling along one of the cracked joints...
I coated the joint first with some Cornice Cement using a 50mm Scraper, and then pushed the mesh into it, and then overcoated it with more Cornice Cement using a 100mm Scraper running along the "shoulders" of the groove. It wasn't exactly "a walk in the park" as they say, but with some care I was able to get the strip into the joint and cover it without any "reflected" pattern of little dimples showing up on the finished surface...

So - what do you all think? I reckon she'd make for a very strong new joint where my Backblocks are missing, but I'm worried somewhat about whether sideways expansion/contraction (ie. across the 65mm width of the strip) due to temperature changes over time might end up being a problem somehow. I mean, they do use meshy-metal Corner Beads at external corners of walls, but the temperature in a room is not as bad as up at the ceiling, and sideways expansion of the metal corner strip can simply push the corner out a fraction of a millimetre sideways when "give" is required. A ceiling can't do this; as a result, the bond between the Cornice Cement and the metal strip might have a sideways shear failure...

The other problem might be the incidental flatness of the ceiling v's the most-probably greater flatness of any length of 0.6mm metal strip. Will lengths of metal strip (say, 1.2m long...) be able to flex enough to conform to the ceiling, without showing themselves through the plaster I try to overcoat them with?...

Your opinions please Gentlemen...:cool:

Many Thanks,
Batpig.

Attached Thumbnails http://www.renovateforum.com/attachm...1&d=1233299344



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