What's the best way to stick up a picture rail?

[PiafPilaf]

Lath and plaster walls, 1930s house. Previous picture rail was done really badly! Wall is not completely flat. Any ideas?

I've stuck one up using No More Nails in a Victorian house which had modern plastered walls. The proper way to put one up is screwed to the wall and the screw holes in the wood filled so you can't see them.

How badly not flat?

If you will want to hang pictures from it the only way to do it is with screws. No more nails is messy and will ruin your walls when it inevitably falls off a few months later.

Countersunk screws. As it is L&P you have to detect where the studs are, by tapping, or with a magnet, or shining a light across the wall, or by drilling tiny test holes, and drive the screws into the studs. They might be 600mm apart, or two feet.

They're slightly wobbly - ie look flat to the naked eye but the picture rail won't lie flush to the wall all the way along. I considered No More Nails but thought the unevenness would count it out, but I'm worried about screws just falling out of the wall. We're not going to hang pictures from them - would rather not take the risk

screws driven into the studs will not "fall out"

Once the rail is well screwed, you can hang pictures or even mirrors from it.

Gaps can be filled with flexible decorators caulk once the rail is screwed on, usually from a tube, and pressed smooth with a wet finger. You can paint it when dried.

Okay thanks. Does it make a difference that they have been reskimmed? Magnet isn't finding anything..! Can't hear a difference when knocking either.

Mark two lines where the rail will run. Drill a few small holes between those lines, starting six inches apart. Poke a Special Tool through those holes, and feel sideways until it touches a stud. Withdraw the Special Tool and mark with a pencil the position on that stud. Then feel it from the other side and mark the position of the other side of that stud.

Once you have found two of the studs, measure their spacing and you will know about where to start for the next one. Decide how thick the L&P is. You will need screws that are long enough to pass through the rail, the L&P, then about 35mm into the studs. You do not need plasplugs because you are screwing into wood.

I can provide you with a Special Tool for £50 plus postage. Or you can make one by bending a piece of wire coathanger into a curve.

I'll try making one! Thank you!

screws and fill the gaps with car body filler, great for coving and skirting boards too.