Brick up old chimney

[magbl]

Hello!

I'm in the process of installing a fireplace in our old house. I've opened up to the chimney where I will install the fireplace, but the chimney is about 5 cm inside the rest of the wall, and I would like to bring the chimney out to the same depth as the rest of the wall. The question is just how.. The house is old, and the chimney is built in the early 1900s, so I assume it's lime mortar. One option I've considered is to coat and plaster and then build on about 25mm lightweight concrete blocks and then plaster a bit more on that. Another option is to plaster the entire chimney out about 5cm if that's possible? I've also heard of panels that can be placed on the chimney that are fireproof.
I would prefer to avoid putting too much load on the wooden floor.

Thanks in advance!

Magnus

 

[magbl]

Thanks for the suggestion. However, I don't think the chimney sweep will approve gypsum against the stove since there should be a firewall there. What I'm planning to do now is first plaster the chimney stack with serpo 224 mortar, then build with aerated concrete blocks (50x400x600mm) using the same mortar with extra adhesive that strengthens the joint between the chimney stack and the aerated concrete. Then I will plaster with render on the aerated concrete blocks. This was a tip I got at the local Beijer building supplies store. What do you think about that?