The sea containers can be stacked, however if the bottom container didn't have its openings/modifications designed a load above (same for footings) then it may not be so straightforward as the skins also bear some load and you usually weld support posts against the cut edge - same goes for waterproofing/flashing between top and bottom container, also there will need to be some engineering and thought going into the roof penetration for stairs and power/water which may need additional bracing. I think the easiest and most cost effective option would be to strip whatever roofing you have and then pour a concrete slab across your existing two containers with the existing container roof acting as the formwork, then build a light weight up structure out of steel or timber framing about 2/3rds the width of your existing containers and leave the other 1/3rd as your outdoor terrace. This will also give you the option to extend the slab beyond your container to form a cantilever or supported balcony to extend your terrace, provide shade to the existing containers and break up the 'blocky' structure you would get from adding an identical rectangle on top. If you had a bit of cash spare then perhaps a corten steel (sea container material) staircase from existing container to upper floor would be a nice touch and cool reference to the house structure, depending on what your interior looks like - would be awesome to weld it to look like the roof has just been peeled down for the staircase but I'm probably breaking the budget now!!

Yes, when you have kids ..two living areas is a must..but then won't you make up for it with the Master suite upstairs ? complete with a retreat ? We are in an apartment roughly 150m2 not counting our deck and we have 4 bedrooms , 2 bathrooms 2 living areas. If not for the two areas I'd go crazy

Hi Bella, I think it is smart to be strategic in how you approach council. My suggested process as follows: 1. Talk to your neighbours, show them what you have in mind. The goal being to keep them on your side. Ask for their honest opinion- better they give it now, than tell council about it during DA. Objections can be a major issue (even just 1). 2. Engage a private Town Planner for 1 hr. Show them your sketches. Ask them to review how compliant it is. There are many layers to this, some depending on what part of Marrickville you are in- heritage, flood, etc. Then all the typical for inner west- shadowing (the biggest issue for 2-storey alts&adds), FSR, tree conservation, on-site water management, build form/bulk and scale....the list goes on. Town Planners are around $200/hr and it may be the best $200 you spend during DA. Many architects will consult TP's after the DA goes in. This has never worked well for us. You can save yourself the $200 if you want to wade through councils many volumes of DCP's and LEP's. Frankly they hurt my head! My honest advice would be to submit the most compliant plan possible. This may mean some big compromises from you.....BUT.....the end goal is to get an approval. A DA rejection is $$$ lost and time lost. Once you have your approval, you can go back Oliver Twist-style and ask for more (eg: the compromises you made) with a Section 96. If they reject a s96- it's no major $$ or time lose. You can still appeal a 96 rejection to council or court. There is less to review,meaning less expense to you. Do a Pre-DA meeting with council. You will know straight up where they are going to nit-pick you. Make the adjustments for DA, then try again in s96 if you are that committed to it. I've not commented on when you engage an architect. Probably after 2 though. Always use local professionals. They know how to manage the council. Good luck!

what a great house! is the garden overshadowed from next door, are there any potential views from upstairs, what's the shape of the roof and what shape roof is acceptable to local council, we need to identify the potential size and shape of the "headroom" for the upstairs floor area, what is the position of the workshop, is the terrace above the carport used, what is the size of the carport, how do you reach the terrace, the steps off the end of the front verandah show "up" does that mean that the carport is higher than the house, what is the distance from the side of the house to the side fence on the carport side, is there an existing porch or verandah next to the laundry, are there steps at the back...and some external photos would also add inspiration