disaster - lathe & plaster please help!

Hi everyone
trying to mount curtain rail holders. Problem is that there is nothing behind the paper thin victorian plaster save lathe & plaster. Clearly not suitable for mounting anything load bearing! Have knocked some of the plaster above the window away, can't see any timber or brick to mount some timber on. Anyone got any ideas? The windows are new UPVC, and clearly can't put curtain rails through the fascias. I'm worried about what the timber I need to put up will be attached to (or resting on?)
Any thoughts gratefully received, I'm just desperate for some curtains rather than the attractive bin bags which are currently keeping the light out (nice) :
ta
Lucy

Lucy182, Welcome.
Out of curiosity, how do you end up with uPVC window in a lath and plaster wall? Windows are usually on external walls, whereas lath and plaster is used for internal walls.

How old is the property? Are you sure it's lath and plaster

sure as I can be ! it's 1 inch strips of very thin wood, covered with and botched atround with grey black cementy gubbins. I take that to be the lathe and plaster as they've knocked internal walls sown ( and ceilings_ and that's what it's been. That doesn't form the external wall, it's covering the external wall up. what I'm worried about is how far back the external wall is (I suppose that can only be the width of the double glazing) but should I just strip it all back to the external wall, remake with a length of timber then replaster?

Laths are used instead of masonary in the construction of internal walls. Since substantial masonary, is pretty much, pre-requisite, for the external walls, laths would just be, plain unnecessary.

Even the inner surface of an external wall is still part of the "external wall". Even in a Victorian house that has lath and plaster internal walls, the internal surface of an external wall would usually be plastered directly onto the brickwork. (laths being unnecessary on masonary).

If you do, indeed, have laths above your window opening, I'd suggest that they were introduced beneath an arch to square off the top of the opening. If this is the issue, you should find solid masonary by fitting your curtain rail somewhat higher.

Another possible cause for confusion, is that some victorian houses used Wooden lintels. If you have drilled and found wood, it is quite possible that you have found a substantial piece of timber (not the feeble stuff used for laths).