We are having a wood burner installed, the floor has Marley tiles as dpm, they were removed were the hearth will go, exposing bitumen. (Marley tiles did not contain asbeston, but bitumen wasn’t checked). 
 

What can I do to not having to screed over the whole living room, but make hearth stick to the floor? 
 

Everywhere else will have a plastic dpc, xps and then laminate flooring. 

What hearth and how laid? 

Mortar or tile adhesive depending hearth 

The weight will hold it in place 

The hearth is quartzite. Just an inch off from chimney sides. Two separate pieces. One for the wood burner and the other in front of the fireplace. Covering the bitumen area.