Rendering internally but which lime to use?

[DIYedboy]

Because I am fitting a woodburning stove onto the hearth in my 1930's semi it seems the only surefire way to ensure the chimney breast surface doesn't blow/ crack or fall off is to have it rendered with a sand/ cement and lime mix.

I assume 2 coats will be necessary and I need to add lime, but which one? Hydraulic, non-hydraulic, NHL2, 3.5, 5.....................help me I'm suffering from lime overload!

 

[DIYedboy]

How disappointed am I?............all you whizzkid plasterer's and no-one answers me question!

So, for the sake of anyone else who wants to know the answer, here is what I believe it to be:

If you are using cement in the render, you must use HYDRATED lime.

For extra info, I was going to 2 coat render my chimney breast cos I'm putting in a woodburner stove n only render will stay stuck to the 1930's bricks unless you want to buy super expensive vitcast heatproof plaster

 

[craigie10]

Loads of info on lime here. http://www.masonsmortar.co.uk/knowledge/