Best way to screed over unusual constructional hearth

[Sprocker]

Hi all

Would anybody be able to advise me the best way to screed my constructional hearth to be level with my floor boards.(around 20mm) I have a void behind the constructional heath that goes down to the subfloor and has the dpc running on top (seems to be the cavity wall), I was thinking of bridging the void with roof slate and screeding but I'm also concerned about bridging the dpc that runs through chimney breast, *Pics attached* the last pic is with the slate fitted over the void

Any advise would be great
Thanks in advance

 

[bobasd]

your front hearth is surrounded by a margin - the margin sits on joists or joist tails.
all trimming joists in contact with the hearth risk rot damage unless they are sitting on DPC's.
the total hearth needs to be dug out to a course below the joists.

what is your future intention with the fireplace and hearth?

dig out & post pics of what you've exposed - & then search for similar threads for further info?

 

[^woody^]

Normally, a liquid DPM is applied and then a suitable self leveling compound.

 

[Sprocker]

Hi
Ideally I didn't want to dig the existing hearth out and only want to screed level with the floor boards, I eventually want to get a wood burner installed and a slate hearth fitted
Thanks

 

[Sprocker]

Hi woody

What liquid dpm could you recommend?
Also do you thing the bridging the void with slate is a good idea ?
Thanks again

 

[^woody^]

Have a look at products from BAL. Stopgap F77 comes to mind, but check the use specification.

You should fill any deep voids to avoid the chances of cold spots. So either fill the void and concrete over, or use the slate but only after filling the void below. Stick the slate down with cement or a no nails type adhesive.

 

[Sprocker]

I wouldn't be able to fill the void as it's the cavity between the walls and the void goes in the the subfloor under the floor boards so I'm just going to have to rest the slate in place I think, I will look for the liquid dpm. Would you run the dpm up the walls slightly over the the original dpm that runs in between the chimney breast?
Thanks

 

[^woody^]

Yes, it's always better to try and overlap any DPM. If that BAL product or similar is too expensive, then a high quality bitumen based product my acheive the same results.