If I fix a batten to the house do I need posts in the lower part or can I basically rest H4 timber on the rocks .
Its very hard digging post hole in this stuff!
Welcome to the Workshop community @DickDalek. I'd be happy to start the discussion.
There are a variety of post stirrups available which could suit this application. My first concern would be the rocky outcrop does not appear to be particularly level. Did you intend on levelling out the rock, in order to place the H4 timber on a flat surface? That seems to be considerably more work, than to chemically anchor stirrups such as Pryda 65mm Hot Dipped Galvanised Half Post Anchor at specific heights to find level.
Another thought that occurs to me is, would an engineer and property survey be required to assess the suitability of the site? Is that rock ledge, solid enough to support the load on the shear edge? Possibly things worth considering.
Let me tag @ProjectPete to see if he has some experience in such a decking application.
We look forward to seeing this project come together. If I can be of assistance or if you had any further questions, please let me know.
Some levelling would be required ,perhaps leaving /filling 500mm from deck edge to fence base.
What do you mean by chemical fixation of the stirrups.
What is the maximum length that the joists across from the house can be ?
Chemically anchoring is where you drill into the rock with a masonry drill to a depth that is determined by the application. You then use a chemical adhesive like Ramset 750ml Chemset Anchor Cartridge to glue threaded rod down into the substrate. Once you have a solid fixing point, you can bolt stirrups or other mounting brackets to the threaded rod.
The maximum length of the joists would be determined by their dimensions, the fixing methods, and the load on the deck. It might be wise to seek advice from a professional such as an engineer.