hairline crack

Just filling it with filler is not likely to work with a moving object. You might find that if you open the crack up about an inch each side and about quarter inch deep, bed scrim in with filler and top it off flush that it will hold.

The problem is that the force trying to split it open could be enormous if the house is settling, and it may be difficult to cure it.

BTW, scrim is an open woven tape used by plasterers to bridge joins in plasterboard, etc. They stick it into place with plaster and then plaster over the top when it's gone off.

Rob Graham

Thanks for that advice Rob.

I had a similar crack in my living room, although my house is only 12 years old. I got a shave hook and scraped down the crack with the point, making a 'v' shape into it, I then filled with ordinary filler sanded down and repainted with emulsion. In just over 12 months no re-cracking.

HTH

John

This approach might well have worked but only if there is no further movement. In the OP's case he's done it before and the crack reappears, indicating further movement. Frankly, if these is much movement I think it will be very difficult to cure without stopping the movement in the first place.

Rob

S,

I have successfully used painters caulking in this sort of situation. I would suggest that you 'rake' out the joint to around a quarter of an inch (and more if necessary) and then fill - the reason: the caulking will expand and contract to take up the movement and anything less will stop that process.

A link here to give some details

As a matter of interest, if the gap has stayed the same size over the years and there are no other external signs - tehn it's unlikely to be settelement in the true sense but merely the boards expanding and contracting - especially if they are in or near a humid atmosphere.

Hope this helps

Brian G

Its in a kitchen but just below a metal support beam in the ceiling so I suspect settling rather than moisture/expansion as the cause.