Hi, I’m looking to build a low level deck just outside the back door of my concrete slab townhouse. It’ll be on part concrete slab and part lawn. The height from the slab to the doorway is about 95mm and it slopes down the length of the house till approximately 150mm. The area doesn’t get sun which is probably why there’s moss growing on the lawn. Would a wood structure be able to slow the deck to be flushed with the doorway? Would it be wiser to use aluminium/steel foundations instead of wood to prevent potential rotting? Thanks!
Welcome to the Workshop community @Berns. It's wonderful to have you join us, and many thanks for your question about deck construction.
An extremely low-level deck and a damp environment is never a good combination. 95mm working height would be considered very low. So low that you'd need to turn your frame 90 x 45 H3 timber on its 45mm side to fit. Over the grassed area, it would be best to use galvanised stirrups for support, and I'd suggest you'll need to remove soil to create a more significant gap between it and the deck's frame. Sufficient drainage needs to be installed to ensure no water stands under the deck.
There needs to be sufficient airflow and drainage under your deck. Without it, you can expect the life of your new deck to be limited.
I'm looking forward to hearing more about your project and offering some potential solutions for your build.