I've got a rear extension built of thermalite blocks which have been rendered. I want to fix some trellis to it for some climbing plants, and also an outside light. I've just been reading some archived posts about the problems of getting a good fixing in this stuff - obviously some trellis with a bit of clematis on it doesn't present the same problem as putting up kitchen cabinets containing the family silver, so I reckon I should be OK with some long plugs and screws.
What's bothering me more is that I do remember being told about penetrating damp problems being created by puncturing the render with screws in situations like this. Anyone have any experience of this?