Plaster walls can be dented by a finger nail or a screwdriver tip quite easily - asbestos sheeting will feel very hard. So in a plaster wall the painted surface will push in easily.Asbestos In Plaster Walls On an asbestos wall you will be able to put a scratch on the paint surface but pushing in will be very difficult.

its plaster ..the boiler was replaced ..the plumber made a hole in wall ..and the hole was patched afterwards ..nowher in uk can you buy a product with asbestos in it to patch a wall .

All you can do is have the material tested. There is no other way to know if it is asbestos. It is most likely not.

I was turning on the boiler in the new house I'm renting in the uk and I noticed the brick work was exposed (where the flue went). However we had one of those awareness courses about asbestos in work so I got scared.

It is about 1 or 2 mm thick and has left a white stain on the brick work. I don't see any fibres but something that is a bit thicker that looks like rock.

My head says it is plaster wall and landlord said that there was no asbestos by boiler but plaster wall that got damaged from boiler installation four years ago (we got it through reputable estate agent). However I'm worried that he's saying that because otherwise he would have to do something.