New answers tagged lath-and-plaster
You can also (apart from DA01's answer): Drill a hole to see if a red 'powder' is what's inside. Knock on it. Listen to how it resonates. It may require some masonery 'insight', but i bet it can help and You could distinguish if there's a open place (like between metal sheets) inside. Combine few of these approaches to get an answer.
Yes, you can cut a hole in the plaster and see if there is brick behind it. Perhaps an easier way is if this is on an outside wall and the brick no the outside goes all the way up. If so, odds are that it goes all the way up on the inside, as this would likely have been a full masonry chimney when it was built (as opposed to modern fireplace inserts which ...
Impossible to answer in general, and hard to answer in specific without actually seeing it. Photos would help, but seriously, I'd suggest you bring in a pro (or several pros) for advice and estimates. After they tell you what the options are for that specific situation, you can decide how much or how little you want to do yourself. In the US, I'd suggest ...
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