Constructional Hearth..Construction of..

[lovelyjob]

Hi all. The picture shows the old hearth which I have now removed and opened up the chimney breast builders opening and am about to put in the constructional Hearth. The bricks you can see at the moment were the existing hearth perimeter and those will go as it needs to extend a little more from the breast. (Not sure yet whether it's easier to create a new shuttering former or lay down some blocks as a retaining wall). I have quite a lot of rubble and brick pieces left over from the opening up...can I crush this up with club hammer and use as the hardcore base...otherwise it's more trips down the dump!

Also, what is the construction procedure as I thought I might as well include a DPM. The overall size of hearth will be 1400mm wide, 900mm out from back of breast and an infill height of 350mm.
I know the concrete hearth has to be 125mm Minimum deep and don't want to mix more than I need to, so can I use the broken up rubble to infill the rest or do I really need a proper Hardcore...type 1?

Do I need a screed finish, and if so how thick...or is that purely aesthetic. i have bags of ready mix general purpose concrete at the moment and was going to us that.

Procedure in layers:...is this correct..say

HARDCORE 195mm
SAND BLINDING 30mm
DPM
CONCRETE 125mm

or should the DPM go down first nearest the ground, then the sand...etc?

Most obliged for your help. View media item 68537

 

[tony1851]

dpm usually goes above the hardcore (the sand is to prevent puncturing of the sheet) and then the concrete on top of that.

 

[lovelyjob]

Thanks for reply Tony. I see your advice is as my option a. Thanks.