How to build composite deck fascia on concrete slab?

matdiy

I'm placing a low lying ekodeck on a concrete patio on timber joists. The patio is raised above the yard height so I am planning to add a single step in. I'm trying to determine where to finish my deck relative to the slab which depends on how I install the fasica for the first step. My options so far are:

(a) Install fasica on timber subframe only and trim it so it finishes before the concrete. Therefore it can be flush to the side of my house. This isn't viable as my deck is only 75mm height this would cause a very small first step.

(b) Deck overhang concrete by around 25mm and then install bottom of fascia basically directly onto concrete. 25mm comes from 23mm fascia thickness plus 2mm gap. Main downside is attaching the bottom of the fascia directly into concrete. 

(c) Deck overhang concrete by around 50mm and then install bottom of fascia onto a 25mm thick batten installed on the concrete + spacer. This would be my preference as that overhang also allows full deck boards all the way to the house. However, I am unsure if this is not advisable for some reason. I've attached a quick illustration with this setup where grey is concrete, blue is packers. Yellow is joist/batten and brown is deck/fascia. 

Thanks in advance!

JacobZ

Hi @matdiy,

I'm sorry to say, but I have some concerns about the design of your deck.

Building decks low to the ground reduces airflow beneath the deck, which allows moisture to build up and adds to the risk of rot. 

Having your deck this low to the concrete massively increases the risk of rot and adding a fascia board to cap the end of the frame closes off the one spot where air can flow.

Unfortunately, I don't think a timber deck is a viable option unless you can increase the clearance from the concrete.

You may be better off looking at something like outdoor tiles for your patio.

Allow me to tag @Dave-1 and @Jewelleryrescue to see if they have any ideas they could add.

Let me know what you think.

Jacob