DPM in fireplace

[CharlieB1981]

removing tiles etc in a old fireplace i've found that it was basically constructed from putting 2 inch of concrete and ballast directly over a soil base with no dpm. the concrete has cracked over the years- assume due to movement underneath and weight of the fire on top.

i'll be having a stove installed and so digging this out to lay it with a proper sub base and level off but is there any danger around laying a DPM with the heat from a fire, would just several coats of liquid DPM work.

hearth is about 1m x0.6m and is against a party wall of a semi detached.

thanks in advance

 

[dann09]

What you'r describing sounds like the back hearth area. Any chance of a few pics?

Typically, where the fire opening/back hearth and front hearth are built off soil you will find that the whole hearth area is trimmed with a fender wall.

If there are no damp issues then you might, perhaps, leave well alone, and cover with a decorative hearth(s) (eg. in slate or stone) of the HETAS/Bldg. Regs required dimensions.

If you do dig it out, then lay a DPM below say, 4" of conc. and cut the DPM at the finished conc surface. Then drop the decorative hearth(s), as above, on top of the concrete.